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FoodandAgricultureOrganizationoftheUnitedNations

FAO LIBRARY AN: 361047

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FISHERIES BRANCH LIBRARY

FIDI NF 220 52174

byPaai A. WickensMarine Biology Research InstituteUniversity of Cape TownRondebosch 7700South Africa

FAOFISHERIES

TECHNICALPAPER

FoodandAgricultureOrganizationoftheUnitedNations

Rome, 1995

The designations employed and the presentation of material in thispublication do not imply the expression of any opinion whatsoeveron the part of the Food and Agriculture Organization of the UnitedNations concerning the legal status of any country, territory, city orarea or of its authorities, or concerning the delimitation of itsfrontiers or boundaries.

M-40ISBN 92-5-103687-X

All rights reserved. No part of this publication may be reproduced, stored in aretrieval system, or transmitted in any form or by any means, electronic,mechanical, photocopying or otherwise, without the prior permission of thecopyright owner. Applications for such permission, with a statement of thepurpose and extent of the reproduction, should be addressed to the Director,Publications Division, Food and Agriculture Organization of the United Nations,Viale delle Terme di Caracalla, 00100 Rome, Italy.

0 FAO 1995

PRETAilATION OF THE DOC

Although the FAO recognizes the competence of the International Whaling Commission inmatters related to the management of whales, the FAO has a clear interest in marine mammalswhen they are caught as bycatch (and thus their conservation) and their predation on commerciallyvaluable fish as it affects the supply of fish for manldnd.

FAO's mandate, as it relates to marine mammals, is mainly executed through the FisheriesResources and Environment Division. Among other responsibilities, this division is concerned withsetting and monitoring environmental standards for protecting fishery resources, fish habitats andfisheries. Clearly, in many areas, fisheries and the capture of marine mammals form common areasof activity. FAO has been responsible for, and involved in, a number of programs that eitherdirectly or indirectly, address the five activity areas expressed for the protection of marinemammals by the Global Plan of Action for the Conservation, Management and Utilization of MarineMammals'. This plan was developed between 1978 and 1983 by the United Nations EnvironmentProgramme (UNEP) and the FAO. The objective of the plan was to promote the effectiveimplementation of policies for conservation, management and utilization of marine mammals whichwould be widely acceptable to governments and the public.

This publication, which has been prepared through an author's contract, is a contribution toresearch on problems arising from interactions between fisheries and marine mammals, in this casepinnipeds. We hope that it will help managers and others to improve methods of fisheriesmanagement and provide a valuable reference for future workers.

The cover page has been illustrated by M. Picker.

Distribution:

FAO Fisheries DepartmentMarine Sciences GeneralAuthor

UNEP 1988. Marine Marrunals Plan of Action: Evaluation of its Development and Achievements.UNEP Reg. Seas. Rep. Stud. No. 102. 43pp.

iv

Wickens, P.A.A review of operational interactions between pinnipeds and fisheries.FAO Fisheries Technical Paper. No. 346. Rome, FAO. 1995. 86p.

ABSTRACT

This review documents the available literature on pinniped/fisheries operationalinteractions, including as much infoiiiiation as possible from both scientificpapers and local reports. Seven areas are examined worldwide and the status ofthe species found throughout these areas is reviewed. The interactionsdetrimental to fisheries are described in terms of the extent of depredation, geardamage and disturbances during passive and active net, trap and line fishing andfish farming. The mortality of pinniped species is detailed in terms of numbersdying during each of the different types of fishing operation. Mitigationmeasures that have been tried in different areas are discussed.

Interactions occur throughout the world and vary greatly in extent and in theirimpact on either a fishery or pinniped population, ranging from an infrequentinteraction in a specific area to large-scale problems causing population declinesor substantial economic losses. Thirty six of the total of forty-five pinnipedshave been recorded as being involved in some form of interaction with fishingoperations or fish fauns. Fourteen interactions involve pinnipeds only and haveno effect on fisheries. No interactions are recorded as being only detrimental tothe fisheries and not to the pinnipeds involved. Nine pinnipeds have no recordedinteractions with fishing operations.

CONTENTS

Page

ABSTRACT iv

IN'TRODUCTION

NORTHEAST PACIFIC OCEAN 42.1 General Situation 42.2 Detrimental Effects on Fisheries 5

2.2.1 Depredation 52.2.2 Gear Damage 82.2.3 Disturbance of Operations 10

2.3 Detrimental Effects on Seals 102.3.1 Incidental Entrapment 102.3.2 Deliberate Killing 19

2.4 Mitigation Measures 20

NORTHWEST ATLANTIC OCEAN 213.1 Species Distribution 213.2 Detrimental Effects on Fisheries 22




NORTHEAST A 1LANTIC OCEAN 264.1 Regional Description 264.2 Detrimental Effects on Fisheries 27




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NORTHWEST PACIFIC OCEAN 375.1 Detrimental Effects on Fisheries 37

5.1.1 Depredation 38

5.1.2 Gear Damage 38

5.1.3 Disturbance of Operations 385.2 Detrimental Effects on Seals 39

5.2.1 Incidental Entrapment 39

5.2.2 Deliberate Killing 41


SOUTH PACIFIC/ATLANTIC OCEANS 426.1 Species Distribution 426.2 Detrimental Effects on Fisheries 43

6.2.1 Depreciation 436.2.2 Gear Damage 436.2.3 Disturbance of Operations 44

6.3 Detrimental Effects on Seals 446.3.1 Species Affected 446.3.2 Incidental Entrapment 446.3.3 Deliberate Killing 45


SOUTH ATLANTIC/INDIAN OCEANS 477.1 Species Distribution 477.2 Detrimental Effects on Fisheries 47




SOUTH INDIAN/PACIFIC OCEANS 528.1 Species Situation 528.2 Detrimental Effects on Fisheries 53




vii

CONCLUSIONS 579.1 Introduction 579.2 Quantification of Interactions 579.3 Summary of Extent of Interactions 589.4 Mitigation Measures 59

LITERATURE CITED 64

TABLES

Species and common names for all extant pinnipeds and the IUCN RedList (1993) status of the species 2

Summary of reported cases, of pinnipeds interacting with fishing operations . . . 60

Summary of reported cases, of fishing operations/fish farms causing mortalityof pinnipeds 61

Summary of reported cases of pinnipeds interacting with different types offishing gear in different areas 62

5 Summary of reported cases of different types of fishing gear in different areasaffecting pinnipeds through mortality/entanglement. 62

IGURE

. Distribution of pinnipeds throughout the world, the geographic areas used 3

1. INTRODUCTION

Pinnipeds and fisheries interact in a number of ways and these interactions may affect eitherthe pinnipetl, the fishery or both. Broadly there are two forms of interaction. A "biological" or"ecological" interaction in which pinnipeds and fisheries both utilise the same resource/s resultingin potential competition between the two which is mutually disadvantageous, although notnecessarily equally so. An "operational" or "direct" interaction is that in which pinnipeds andfisheries interfere with one another during fishing operations resulting in a cost to the fisheriesthrough loss or damage to catch, damage to fishing gear and disturbance of operations, andincidental or deliberate mortality, injury or harassment of the pinnipeds.

"Biological" interactions have been discussed by many authors and in various forums (eg,Melteff and Rosenberg 1984, Beddington et al. 1985, Malouf 1986, Butterworth and Harwood1991, UNEP 1992). In this review only "operational" interactions are considered, je, the directlosses incurred during fishing operations by fisheries and pinniped populations. There are at leasttwo related areas of interaction that are neither "biological" nor "operational"; one influencingfisheries catches and the other having a detrimental effect on pinnipeds. The first is the transmissionof parasites from pinnipeds to fish resulting in reduced quality of fish (IUCN 1981, Harwood andGreenwood 1985, Malouf 1986, Bonner 1989) and the other is the entanglement of pinnipeds indiscarded or lost fishing gear causing pinniped mortality (Shaughnessy 1980, Henderson 1984,Fowler 1987, Stewart and Yochem 1987, Scialabba 1989, Croxall et al. 1990, Shomura andGodfrey 1990, Pemberton et al. 1992).

Other related reviews of pinniped/fisheries operational interactions have been either of specificareas or worldwide reviews relating to all or specific fishing operations, and may consider pinnipedsin general or certain pinniped in particular. Such reviews have came from commissioned studies,reviews or workshops, and are often the result of pressure from those with interests in fisheries,je, fishing industries, or those with pinniped stocks in mind, je, conservation groups (Mate 1980,IUCN 1981, Contos 1982, Miller et al. 1983, Northridge 1984, 1988, 1991a, b, Beddington et al.1985, Malouf 1986, Montgomery 1986, Woodley and Lavigne 1990, 1991, Young et al. 1993,Mattlin 1994b, Wickens 1994b, Barlow et al. in press).

Pinnipeds are an order comprised of three families with a total of 33 extant species and anumber of subspecies, resulting in a total of 45 distinguishable pinnipeds (Table 1). Otariidae or"eared" seals include 5 extant species of sea lion and 9 species of fur seal. Phocidae or "true seals"include 18 extant species. The Odobenidae has just one species, the walrus.

This review is divided into seven different geographic regions on the basis of the distributionof pinniped species and the research that has been carried out on interactions in different regions(Figure 1). The Southern Ocean region has been excluded as there are no reported interactionsthere, except where they occur at fishing operations near populated landmasses, in which case theyare considered within the relevant geographic region. There are two fur seal species and 4 "true"seal species in the Southern Ocean. These include Subantarctic fur seals (310 000 seals calculatedfrom Croxall and Gentry 1987), Antarctic fur seals (L6 million seals and increasing, Boyd 1993),

COMMON NAME SPECIFIC NAME

Sea lionsSteller's (Northern) sea lionCalifornia sea lionGalapagos sea lionSouth American (Southern) sea lionAustralian sea lionHooker's (New Zealand) sea lion

Fur sealsNorthern (Pribilof) fiir sealGuadalupe fur sealGalapagos fiir sealJuan Fernandez fur sealSouth American fiir sealSouth African (Cape) fiir sealAustralian (Tasmanian) fur sealNew Zealand fur sealSubantarctic fur sealAntarctic fur seal

True sealsGrey sealEastern Atlantic harbour (common) sealWestern Atlantic harbour (common) sealWestern Pacific harbour (Kuril) sealEastern Pacific harbour (corrunon) sealUngava sealHarp sealLarga (spotted) sealArctic ringed sealOkhotsk Sea ringed sealBaltic ringed (Baltic) sealSaimaa sealLadoga sealCaspian sealBaikal sealRibbon sealHooded sealAtlantic bearded sealPacific bearded sealMediterranean monk sealHawaiian monk sealSouthern elephant sealNorthern elephant sealWeddell sealRoss sealCrabeater sealLeopard seal

WalrusesAtlantic walrusPacific walrus

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Table 1

Species and common names for all extant pinnipeds and the IUCN Red List (1993) status of the species. "Endangered" : species in danger of

extinction and whose survival is unlikely if the causal factors continue operating. "Vulnerable" : species likely to move into the "Endangered"

category in the near future if the causal factors continue operating. "Rare": species with small world populations that are not at present"Vulnerable" but are at risk. "Insufficiently known": species that are suspected to belong to one of the above because of lack of information.

Eumetopias jubat USZalophus californianus californianusZalophus californianus wollebaekiOtaria byroniaNeophoca cm creaPhocarctos hookeri

Callorhinus ursinusArctocephalus townsendiArctocephalus galapagoensisArctocephalus philipiiArctocephalus australis gracilisArctocephalus pusillus pusillusArctocephalus pusillus doriferusArctocephalus forsteriArctocephalus tropicalisArctocephalus gazella

Halichoerus grypusPhoca vitulina vitulinaPhoca vitulina con colorPhoca vitulina stejnegeriPhoca vitulina richardsiPhoca vitulina mellonaePhoca groenlandicaPhoca larghaPhoca hispida hispidaPhoca hispida ochotensisPhoca hispida botnicaPhoca hispida saimensisPhoca hispida ladogensisPhoca caspicaPhoca sibiricaPhoca fasciataCystophora cristataErignatus barbatus barbatusErignatus barbatus nauticusMonachus monachusMonachus schauinslandiMirounga leoninaMirounga angustirostrisLeptonychotesOmmatophoca rossiiLobodon carcinophagusHydrurga leptonyx

Odobenus rosmarus rosmarusalobenus rosmarus divergens

STATUS

Vulnerable

RareVulnerable

Vulnerable

Vulnerable

Insufficiently known

VulnerableEndangeredVulnerable

Vulnerable

EndangeredEndangered

5: SOUTH PACIFIC / ATLANTICGalapagos sea lion

South American sea lionGalapagos fur seal

Juan Femandez fur sealSouth American fur seal

Antarctic tur sealSouthern elephant seal §

Wodell sealLeopard seal

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6 : SOUTH ATLANTIC / INDIANSouth African fur seal

7: SOUTH INDIAN / PACIFICAustralian sea lionHooker's sea lionAustralian fur seal

New Zealand fur sealLeopard seal

Fig. 1: Distribution of pinnipeds throughout the world (shaded area), the geographic areas used in this report andthe species occurring in each of these areas. Freshwater species are given in italics. Southern Ocean species

are shown in outline text (§ = also breeds in South America) and are only shown where they are involvedin interactions with fishing operations in any of the seven designated areas.

1: NORTHEAST PACIFIC 2: NORTHWEST 3: NORTHEAST ATLANTIC 4: NORTHWEST PACIFICSteller's sea lion ATLANTIC Grey seal Stokers sea lion

California sea lion Grey seal Eastern Atlantic harbour seal Northern fur sealNorthern fur seal Western Atlantic harbour seal Harp seal Western Pacific harbour seal

Guadalupe fur seal Ungava seal Arctic ringed seal Larga sealEastern Pacific harbour seal Harp seal Baltic ringed seal Arctic ringed seal

Larga seal Arctic ringed seal Saimaa seal Okhotsk ringed sealArctic ringed seal Hooded seal Ladoga seal Baikal seal

Ribbon seal Atlantic bearded seal Caspian seal Ribbon sealPacific bearded seal Atlantic walrus Hooded seal Pacific bearded sealHawaiian monk seal Atlantic bearded seal Pacific walrus

Northern elephant seal Mediterranean monk sealPacific walrus Atlantic walrus

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Southern elephant seals (70 000 - 800 000 although some of these are also found in South America(Area 5), calculated from Reijnders et al. 1993), Weddell seals (more than 750 000 seals, Reijnderset al. 1993), Ross seals (more than 130 000, Erickson and Hanson 1990), Crabeater seals (morethan 10 million seals, calculated from Reijnders et al. 1993) and Leopard seals (more than 300 000seals, Erickson and Hanson 1990).

The purpose of this report is to document as much literature as possible on pinniped/fisheries operational interactions to form a bibliography of work done in this field; to give someidea of the scale of interactions in different areas; to provide a summary of the key fishing methodsand pinniped species that are involved in interactions; to examine mitigation methods that have beenattempted to alleviate interactions, and finally to synthesize common problems throughout theworld. Every effort has been made to acquire as much of the relevant literature as possible. Muchof the literature is not accessible in scientific papers as much information is often found only in the"grey literature" or in papers on other related issues. Most of the literature reviewed is that writtenin English.

Within each region a brief description is given of the pinniped stocks involved, their stocksizes and trends. The types of fisheries affected or affecting pinnipeds in the region are outlined interms of being either passive (static, fixed) gear which are anchored or left to drift to catch fish asthey approach it (eg, gill nets, longlines, fish or lobster traps) or active (ie, mobile) gear which istowed or moved so that fish are intercepted in some way (eg, trolled lines, lampara nets, trawls,seines purse-seines). The interaction between pinnipeds and fisheries is described with separatelyfor each area. The detrimental effects on fisheries is separated into depredation (g,. seals taking fishfrom lines or nets), gear damage (eg, seals brealdng tackle from lines or tearing nets), anddisturbances to fishing operations (eg, the presence of seals causing fish to disperse). Thedetrimental effects of fishing operations on pinnipeds are described in terms of incidentalentrapment in fishing gear causing drowning and deliberate killing by fishermen. In each areamitigation measures that have been attempted to address problems are described. The reviewconcludes with a synthesis of the problems of quantifying interactions and making comparisonsbetween studies, a synthesis of the species, areas and fishing operations involved and of themitigation measures that have been tried.

2. THE NOR EAST PACIFIC OCEAN

2.1 General Situation

The Northeast Pacific includes the west coast of North America, the west portion of the northcoast of North America, the Aleutian Islands and the Hawaiian islands and the small portion ofSouth America that falls above the equator (FAO area 67 and part of 18 and 77). Twospecies/subspecies of sea lion, two species of fur seals, seven "true" seal species/subspecies and asubspecies of walrus are found in this region.

Steller's sea lion is found along the west coasts of Canada and the USA, including the

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Aleutian Islands with a population size in the area of 55 000 which is decreasing (Reijnders et al.1993) and is listed as "Vulnerable" in the 1993 IUCN Red List. This species is considered to havebeen seriously affected by fishing operations and incidental catches and shooting of Steller's sealions have been suggested as causing the decline in the Alaslcan population (Loughlin and Nelson1986, Merrick et al. 1987, Loughlin 1989, Perez and Loughlin 1991). California sea lions arefound along the coast from Mexico to British Columbia and have an increasing population size inexcess of 145 000 animals (Le Boeuf et al. 1983).

Northern fur seals are found along the entire west coast of Canada and the USA with apopulation size of 904 000 in this area (Reijnders et al. 1993). The species is threatened bymortality from entanglement in driftnets (Fowler 1982, Reijnders et al. 1993). The Guadelupe furseal is found on the Guadelupe Islands and has an estimated population size of 7 348 animals. Thepopulation is increasing (J. Gallo, pers. comm.).

The Eastern Pacific harbour seal is found along the Aleutian Islands, down the west coast ofCanada and the USA. It has a population size in this area of approximately 380 000 animals (fromReijnders et al. 1993). Large seals are found along the Alaskan coast and form a proportion of theBering Sea population of 135 000 (Popov 1982). Arctic ringed seals are found along the AleutianIslands and the Alaskan coast and are a proportion of the Bering Sea population of 70 000 - 80 000(Reijnders et al. 1993). Ribbon seals are found along the Aleutian Islands and the Alaskan coastanimals in this region are a proportion of the Bering Sea population of 60 000 animals (Popov1982). Pacific bearded seals are found along the Alaskan coast and are a proportion of the BeringSea population of 250 000 animals (Popov 1982). Hawaiian monk seals are found only in Hawaiiand have a population size of 1 500 seals. Interactions during fishing are cause for concern(Reijnders et al. 1993) and the species is described in the 1993 IUCN Red list as "Endangered".Northern elephant seals are found along the coasts of Alaska, British Columbia, mainland USA andMexico and have a population size of 25 000 which is increasing (Reijnders et al. 1993). ThePacific walrus is found in Alaska and is a proportion of the Pacific population of 230 000 animals(Gilbert 1989).

2.2 Detrimental Effects on Fisheries

Of the 12 pinnipeds found in this area, 4 (Steller's sea lions, California sea lions, EasternPacific harbour seals and Hawaiian monk seals) are involved in detrimental interactions with passiveand active net fishing and active line fishing in different areas.

2.2.1 Depredation

Passive Net and Trap Fishing

In gill net fisheries fish caught may be lost or damaged, sometimes rendering them unsaleable,as a result of Steller's sea lions, California sea lions and harbour seals in areas ranging from Alaskadown to Mexico (eg, Mate 1979, Fiscus 1980, Everitt and Beach 1982, Malouf 1986, Obee 1987,

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Hoover 1988, Loughlin 1991, Reijnders et al. 1993, Young et al. 1993).

On the Copper River Delta in Alaska, Imler and Sarber (1947) estimated that some 2% ofnetted salmon was damaged by harbour seals. In 1977 Matkin (1978) reported that salmon gill netfishermen from the Copper River had 8.3% of their fish damaged (2.1% of the damage by harbourseals and 6.2% by Steller's sea lions), representing a loss of $517 per boat or $230 000 for the fleetof 44 boats in the area. In 1978 Matkin and Fay (1980) estimated that seals, mostly harbour seals,and to a lesser extent Steller's sea lions, damaged fish in the summer Coghill fishery. Harbourseals caused all of the damage in the Copper-Bering autumn fishery, reducing the potential valueof salmon catches by approximately 2.3% ($210 000). During 1988 a field survey showed that 3%and 0.3% of salmon in nets on the Copper River Delta were damaged by harbour seals and Steller'ssea lions respectively, although fishermen reported that only 1.8% of salmon were damaged byeither of these seal species (Wynne 1990). Although damage from Steller's sea lion was lessfrequent it was more damaging than from harbour seals and fishermen indicated that 82% of salmondamaged by sea lion was unmarketable. Only 10% of salmon damaged by harbour seal wasunmarketable (Wynne 1990). During 1988 Wynne (1990) conservatively estimated financial lossdue to depredation from salmon drift nets to be less than 1% of the ex-vessel value of salmonlanded (approximately $250 000).

In the Skeena estuary, British Columbia, in the 1940's the damage to salmon by harbour sealswas estimated to be 7-12% of the salmon catch and was worst when chinook salmon were beingcaught (Fisher 1952). In Hecate Strait, British Columbia, in 1962 it was estimated that there wasa $54 loss per fisherman from damage to gill-netted salmon attributable to Steller's sea lions (Biggcited in Mate 1980).

In Washington, Scheffer and Slipp (1944) recorded a fisherman as landing only two saleablefish out 13 gilled salmon, the others having been destroyed by seals. In southern Puget Sound,Washington, in 1984 driftnet caught chinook salmon that were unsaleable because of seals attack,ranged from 61.5% of catches in the first week of the season to 1.6% in the week of peak catches,averaging 2.9% between July and September. During this time the income from the fish wasreduced by $4 669 (Geiger and Jeffries 1987). By 1985, in the same area, unsaleable chinookranged from to 1.2% - 22.2% of the catch, averaging 3.1% of the catch during which time thevalue of fish that was unsaleable amounted to $2 946 (Geiger and Jeffries 1987). Damage rates toset-netted chinook were initially zero and ranged up to 54.5%, averaging 11.3% of the catch witha value of $750 (Geiger and Jeffries 1987).

On the Columbia River, in Oregon, examination of salmon delivered to a processing plantduring 1972-77 revealed that 1.0-2.3% of those fish examined were damaged by harbour seals, withvalue amounting to approximately $60 000/year. The percentages were higher in summer andspring, and there figures are underestimates because heavily damaged, unsaleable, fish were notincluded (Hirose 1977). In test fisheries on the Columbia River (although test fishing does differfrom commercial fishing because only a single boat is fishing at a time) all forms of pinnipecldamage affected about 13% of catches between 1972 to 1980 (Everitt et al. 1981). Damage to gill-netted salmon was particularly severe when salmon runs were low and could reach 25-30% of the

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catch whereas during other more abundant runs the damage was only 1.4%. The more sustainedfisheries experienced damage rates of 5-10% of the catch (Everitt et al. 1981). The minimum lossduring the 1980 gill net fishery from damaged fish was estimated at over $100 for all areasconsidered in the study (Everitt et, al. 1981). On the Columbia River in 1981, the pinniped damagerate to spring chinook and steelhead in the April test fishery at Woody Island was 44.7% in 1980(Beach et al. 1981). On the Columbia River, harbour seals damaged 5.3% of coho salmon soldfrom the fall gill net fishery in 1980 and 15.4% in 1981 (Beach et al. 1985). In the winter gill netseasons of 1980, 1981 and 1982 harbour seals in combination with California sea lions damagedto 8.1%, 4.6% and 2.2% of the chinook salmon landed (Beach et al. 1985). In the Youngs Bayterminal fishery off the Columbia in Oregon, in 1980 and 1981 harbour seals damaged 5.2% and9.0% of the chinook catches and 2.7% and 1.9% of the coho catches respectively, for a totalsalmon damage of 3.7% and 5.5% in these years, respectively (Beach et al. 1985).

In northern California an unknown amount of depreciation by sea lions occurred in theKlamath River gill-net fishery. The problem was most severe in geographic areas, near seal haul-outs (Miller et al. 1983). Herder (1983) reported that 13.2% of salmon were damaged in theKlamath River gill net fishery, of roughly $34 077 in value, or $831 per fisherman in 1979/80.

Apart from these salmon fisheries, various other fisheries utilising gill nets lose fish to seals.Log books from 58 vessels of Pacific halibut fishery in Cape St Elias and the Gulf of Alaska from1958/1960 indicated 8.1% of fish caught were damaged or destroyed and, extrapolated to the wholefleet, losses attributable to Steller's sea lions were estimated at $ 500 000 (Bell 1961). In the gillnet and trammel net ocean fisheries sea lions were estimated to take 12.5% of the catch in watersoff Baja California and in southern California most of the 2.2% lost was taken by California sealions (Miller 1981). Miller et al. (1983) estimated losses from gill net fisheries in 1979/80 forhalibut of $ 46 640 (10%), white seabass $ 7 480 (4%) in California, $39 000 (10,2%) in Mexico,rockfish $2 600 (1,4%), white croaker $2 978 (7,1%), barracuda $330 (2,2%), bonito $1270(6,5%) and flying fish $200 (6,4%). Miller et al. (1983) noted that during observations in1979/1980 California sea lions also took herring from gill nets in California.

Active Net Fishing

Steller's sea lions, California sea lions and harbour seals are involved in interactions withround haul (lampara and purse-seine) nets. In Alaska, the Japanese have estimated that 50% ofsablefish caught in purse-seine nets Kodiak region and 20-30% of catch in the Bering Sea, southof the Pribilof Islands is damaged by Steller's sea lions (Burns cited in Mate 1980). In Washingtonharbour seals take fish in the purse-seine net fisheries (Mate 1980). In Yaquina Bay, Oregon,California sea lions are reported to cause some minor damage to the herring round-haul fishery(Brown 1988). In California, anchovy are reported to be taken from purse-seines by California sealions (Mate 1980). In the years 1979/1980 sea lions were observed to take herring from lamparaand round haul nets in California but since this Pacific herring fishery operates on a quota system,if the quota is filled there is only a loss in time, as more time will be required to catch the quota

(Miller et al. 1983).

Active Line Fishing

Steller's sea lions, California sea lions and Hawaiian monk seals take line-caught fish duringvarious types of active line-fishing along the North American west coast and in Hawaii, (Fiscus1980, Everitt et al. 1981, Everitt and Beach 1982, DeMaster et al. 1982, 1985, Malouf 1986,Montgomery 1986, Hanan et al. 1989, Loughlin 1991). In British Columbia seals take salmon fromsport fishermen and anglers at times have reported losing as many as 4 out of 5 hooked fish to seals(Obee 1987). In Oregon on the Columbia River, salmon severely damaged by harbour sealsamounted to 15% of the catch in test fishing in 1976 and 30% in 1977; unsaleable salmonrepresented 5% of the catch in 1976 and 12% in 1977 (Mate 1980).

In the Klamath River, northern California, Herder (1983) reported that in the sport hook andline fishery in 1979/80 less than 1% of salmon and a similar incidence for surfperch, were damagedamounting to little cost in terms of lost fish. In Monterey Bay, California in 1969 California sealions damaged 4% of the caught fish by salmon trollers for an estimated cost of as much as $122000 annually and representing 2.6% of the ex-vessel landings (Briggs and Davis 1972). Californiasea lions were estimated to take roughly 2.5% of the catch in southern California, from thecommercial sport-boat fishery, with the value of fish and gear loss varying between $37 000 and$38 800, over 6% in Baja California and a negligible amount in central California (Miller 1981).In California in 1979/80, sea lions were estimated to cost the hook and line fishery $1500 througha depredation rate of 0.44% (Miller et al. 1983). In 1979/80 California sea lions were estimatedto depredate 1.9%, 0.32%, 0.02-0.18% and 0.1% of salmon caught by the California commercialsalmon troll, partyboat, recreational skiff and salmon and steelhead river fisheries at a cost of $274000, $6 000, $2 300 and an unknown amount respectively (Miller et al. 1983). Sea lion depredationwas also estimated to cost the partyboat fishery for bottomfish $27 000 in 1980 (Miller et al.1983). Hanan et al. (1989) showed that over a five-year period (1984 - 1988) California sea lionsconsistently took similar numbers of fish during each commercial passenger sport fishing trip butthe frequency of sea lion depredation declined over the years.

In Hawaii, monk seals are occasionally seen taking hooked fish from bottomfish fishing linesor near lobster fishing vessels (MMC 1993). During 46 monitored fishing trips, 2 Hawaiian monkseals were seen to take hooked opelu from lines before they could be retrieved (Humphreys 1981).

2.2.2 Gear Damage


In gill net fisheries from Alaska southwards to California, gear damage results frominteractions with Steller's sea lions, California sea lions and harbour seals in different areas (eg,Fisher 1952, Hirose 1977, Mate 1979, 1980, Everitt et al. 1981, O'Hara et al. 1986, Loughlin1991, Reijnders et al. 1993, Young et al. 1993).

In Alaska, salmon gill net fishermen from the Copper River suffered gear damage in 1977

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amounting to $162 per boat or $72 OGO for the fleet (Matkin 1978). In the Copper River Deltaspring salmon drift net fishery in Alaska, Matkin and Fay (1980) estimated that some $150or 1.7% of the value of the fishery, was caused, mostly by Steller's sea lions (80%), but alsoharbour seals. In 1988 net damage by seals in the Copper River Delta was also estimated to bemostly attributable to Steller's sea lion damage (> 84%) and the remainder to harbour seals (Wynne1990). This damage was estimated to cost between $52 000 and $155 000, although this is aconservative estimate because additional losses related to net in efficiencies and lost fishing timeduring repairs could not be estimated (Wynne 1990). In Alaska, fishermen found that the Steller'ssea lions also chewed marker buoys (Mate 1980)!

1 I

In British Columbia Steller's sea lions and California sea lions are reported to make holes ofconsiderable size in the gear when talcing fish from gill nets (Malouf 1986). In Hecate Strait, BritishColumbia, in 1962 estimated losses of $22 per salmon gill-net fisherman from damaged gear wereattributable to Steller's sea lions (Bigg cited in Mate 1980).

In Oregon on the Columbia River in 1980 gill net fishermen experienced 0.6-2.2 cases of geardamage for every 100 hours fished and in 1981 there were 50 instances of California sea lionscausing damage to gill nets (Everitt and Beach 1982). In the Columbia River, approximately 40%of gill net damage was attributed to harbour seals and California sea lions during the winter fishingseason of 1981 (IUCN 1981). California sea lions and harbour seals are also reported tosignificantly damage gear in the sport crab fishery in Oregon (Everitt and Beach 1982).

In the Klamath River, northern California in 1979-1980, Herder (1983) calculated that eachfishermen lost $1600 worth of gill nets. In California in 1980, losses from gill net fisheries wereestimated by Miller et al. (1983) to be $792 for sharks, $24 071 for habilut, $1000 for whitecroaker and $382 for bonito . In 1979 and 1980 it was estimated that sea lions may have causedgear loss to the value of $5 000 in Pacific herring gill nets in California (Miller et al. 1983).

Active Net Fishing

California sea lions are reported to make holes in purse-seine nets in California (Mate 1980).

Active Line Fishing

California sea lions and harbour seals are involved in interactions with various forms of linefishing in California. Herder (1983) reported that in the Klamath River in northern California, theincidence of loss of bait, lures and broken leaders to harbour seals in the salmon sport hook andline fishery occurred, but was less than 1%, and amounted to less than $100 for the season in 1979and 1980. In California in 1980, gear losses to California sea lions were estimated at $12 225 inthe commercial salmon troll fishery and $360 in the salmon partyboat fishery (Miller et al. 1983).California sea lions were also estimated to cost $10 730 in 1980 through gear loss to the partyboatfishery for bottomfish in California (Miller et al. 1983).

2.2.3 Disturbance of Operations


California sea lions, harbour seals and Hawaiian monk seals interact with crab and lobsterfisheries in different areas, disrupting fishing. In Oregon, California sea lions and harbour sealsare reported to remove bait in the sport crab fishery to a significant degree (Everitt and Beach1982). In Hawaii, during 46 monitored lobster fishing trips, a Hawaiian monk seal was seen to tugat the night light used to attract lobster and in doing so chased away the lobster from the trap(Humphreys 1981).

Active Net Fishing

In California, California sea lions enter round haul nets before the bag reaches the boat andfrighten fish out of the net; this is of more concern than depredation (Miller et al. 1983). Californiasea lions are also reported to make holes in purse-seine nets allowing fish to escape (Mate 1980).

Active Line Fishing

In California near San Diego, California sea lions may take the chum being used to catch fishduring sport fishing (Hanan et al. 1989).

2.3 Detrimental Effects on Seals

All of the 12 pinniped species found in this area (Steller's and California sea lions, northernand Guadelupe fur seals, Eastern Atlantic harbour, Larga, Arctic ringed, ribbon, Pacific bearded,Hawaiian monk and northern elephant seals and the Pacific walrus) are killed either incidentally ordeliberately in passive and active nets and passive and active line fishing in various areas.

In an investigation of stranded pinnipeds in central and northern California from 1986 to1992, 169 stranded live pinnipeds (155 California sea lions, 5 elephant seals, 5 harbour seals, 3Guadelupe fur seals and 1 Steller's sea lion) were found to have injuries related to fishingoperations including 116 gun shot wounds, 33 gill net injuries, 13 with fishing tackle injuries and2 with debris injuries (Barocchi et al. 1993).

2.3.1 Incidental Entrapment

Steller's Sea Lion

Steller's sea lions are caught incidentally caught and die during gill net and trawl fishing invarious areas from Alaska southwards to California (eg, IUCN 1981, Mate 1982b, Herrick andHanan 1988, Perez and Loughlin 1989). The total incidental Ici11 of Steller's sea lions from 1973to 1988 has been estimated at 14 000 (Anon 1990b) but fewer have been killed in recent years -

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11

Young et al. (1993) estimated that 27 sea lions were incidentally killed in Alaska in 1990 and 57were killed in 1991.

In Alaska, during a 1977 pilot study, 40-50 Steller's sea lions were taken in salmon gill netsin the Copper River Delta and 10 were taken in Coghill District (Matkin and Fay 1980). Duringa salmon netting study in 1978, 8 Steller's sea lions were captured and released alive despite theCoghill District and none were drowned in the Copper River Delta (Matldn and Fay 1980). In a15-week survey in 1988 a single Steller's sea lion was incidentally caught but was released alivein 387 salmon drift net sets in the Copper River Delta (Wynne 1990). In Prince William Sound andSouth Unimalc, Alaska driftnet and setnet fisheries for salmon, Steller's sea lions were reported tohave been entangled but none died in 1990 (Wynne 1991, Barlow et al. 1990). In Prince WilliamSound in 1991, Wynne et al. (1992) reported 7 Steller's sea lions dyed. Incidental catches ofSteller's sea lions were reported in the Cook Inlet driftnet and set net fishery for salmon but therewere no incidental deaths in 1990 and 1991 (Barlow et al. in press).

In central California, halibut, flounder, and shark gill net fisheries take fewer than 5 Steller'ssea lions per year (Wild 1986); and just one was taken in 1986 in the halibut gill and trammel netfishery (Wild 1987). In the California swordfish/shark drift-net fishery Julian (1993) calculated that8 Steller's sea lions died in 1992. Barlow et al. (in press) report that no Steller's sea lions weretaken in the California swordfish/shark drift-net fishery in 1990, 1991 and 1993.

Since about 1954, Steller's sea lions have been taken in the foreign commercial trawl fisheriesin the Bering Sea and Gulf of Alaska (Loughlin and Nelson 1986) and there are reports of Steller'ssea lions caught in the joint venture trawl, foreign and domestic trawl fisheries in the 1970's and1980's (Loughlin et al 1983, Loughlin and Nelson 1986, O'Hara et al. 1986, Craig and Owen 1988,Loughlin 1990, Perez and Loughlin 1991, Loughlin 1991). Perez and Loughlin (1991) suggest thatthe annual incidental take in foreign and joint-venture trawl fisheries around Alaska declined frompeak levels of 1 000 - 2 000 Steller's sea lions in the early 1970's to less than 100 in 1988. Perezand Loughlin (1991) estimated that the average annual take of Steller's sea lions in the foreign andjoint-venture trawl fisheries of the Bering Sea/Aleutian Islands and Gulf of Alaska regions in theperiod from 1978 to 1988 was 595 animals and reached a maximum of 1756 sea lions in 1982. Inthe 1970's incidental mortality of Steller's sea lions exceeded 25 sea lions per 10 000 tonnes of fishcatch in foreign fisheries in the Kodiak Island/Aleutian Islands area (Perez and Loughlin 1991).Loughlin et al. (1983) note that incidental mortality in foreign and joint venture fisheries in the mid-1980s was fewer than 500 Steller's sea lions annually. Estimates of Steller's sea lion incidentalcatch taken from NRC (1989), excluding live relea.sed and de-composed animals, for the foreign andjoint-venture trawl fishery were 2651 (1978-1987) and 2005 (1983-1987), respectively. Thenumbers declined from 978 in 1978 to just 5 in 1987 in the foreign trawls and from 704 in 1983to 83 in 1987 in joint-venture trawls. Young et al. (1993) reported that the joint venture trawlfisheries which have operated off Oregon, Washington, and northern California have takenapproximately one Steller's sea lion every other year since 1976.

Over the period 1973-88, Steller's sea lions accounted for 87% of the incidental mortality ofmarine mammals reported by observers aboard trawlers in the Gulf of Alaska and eastern Bering

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S- (Perez and Loughlin 1991). In the Bering Sea most were males whereas in the Gulf of Alaska,females were most frequently caught (Perez and Loughlin 1991). Loughlin and Nelson (1986) reportthat most females were mature and from a range of ages while the males caught were young.Seventy three percent of the sea lions were caught at night, probably during net retrieval (Loughlinand Nelson 1986).

The low catches from 1986 to 1988 resulted from the phase-out of foreign and joint-venturefisheries and an expansion of the U.S. domestic fishery (Loughlin 1990). Loughlin (1990) provideda preliminary estimate of an average of 121, and up to 395, sea lions caught in domestic trawloperations in the Bering Sea during 1988. Craig and Owen (1988) report that during the observationperiod from 1978-1988, 4 sea lions were caught in 1176 domestic trawls in 1980 of which one wasreleased alive. 'C (1989) estimated that, excluding live released and decomposed animals, 294Steller's sea lions were caught incidentally in the domestic trawl fishery between 1983 and 1987increasing from 26 to 106 over the years.

Six experimental squid fishing operations off British Columbia between 1979 and 1988resulted in a single Steller's sea lion being taken in 1987 (Jamieson and Heritage 1988).

California Sea Lions

California sea lions have been reported incidentally caught during passive net (gill net), activenet (trawl and purse seine) and active line (troll) fishing all along the North American west coast(eg, DeMaster et al. 1982, Mate 1982a, Herrick and Harlan 1988, Hanan et al. 1993, Reijnderset al. 1993). Lowry et al. (1992) give a figure of about 30 California sea lions, predominantlymales, being incidentally lcilled in gill nets during winter in the Columbia River and some possiblyalso taken in other areas of Oregon, Washington and British Columbia. In the Columbia River inwinter 1981, 4 sea lions that became entangled in chinook gill nets died (Everitt and Beach 1982).Geiger (1985) estimated that in 1981, 45 sea lions were incidentally killed in the Columbia Rivergill net fishery for salmon.

Miller et al. (1983) estimated that in gill and trammel net fishing for halibut and angel sharksin California, 242 California sea lions were incidentally killed in the 1979/80 season. In the fouryears during the period 1983/84 and 1986/87, Hanan et al. (1988) and Hanan and Diamond (1989)estimate that 3427, 2244, 2207 and 4288 California sea lions, respectively, were incidentally killed.In the 1987/88 season, Konno (in press) estimate that 2 725 ± 486 California sea lions were killedin this fishery. Wild (1990) estimated that on average 15.2 sea lions died each year between 1980and 1989 in gill and trammel net hauls for halibut in the region between Monterey and Bodega Bay.

Incidental catches of the California sea lions in monitored hauls of gill and trammel nets forhalibut and angel sharks from central California were reported by Wild (1985, 1986, 1987); 8 sealions were recorded caught in 298 net hauls during 1984; three sea lions were caught in 312 nethauls during 1985 and two sea lions were caught in 421 net hauls during 1986. For southernCalifornia, Collins et al. (1984, 1985, 1986) reported by-catches of sea lions in gill and trammelset nets for halibut, soupfin shark, angel shark and white seabass. Seventeen sea lions were

13

observed caught in 556 hauls during 1983; 15 sea lions were observed caught in 904 hauls during1984 and 43 sea lions were observed caught in 795 hauls during 1985. Between 1983 and 1986,California set net fisheries alone were responsible for more than 8132 sea lion deaths (Collins etal. 1984, 1985, 1986, Wild 1985, 1986). Numbers are given of 847 (6 months of 1990), 1858(1991), 3255 (1992), 1984 (1993) taken in this fishery (Lennert et al. 1991, Julian 1993, 1994,Barlow et al. in press).

Miller et al. (1983) estimated that 952 California sea lions were incidentally ldlled in sharkdrift gill nets in the 1979/80 season in California. Barlow et al. (in press) updated information ofCalifornia sea lion mortality in California drift gill net fishery for swordfish and sharks fromDiamond et al. (1986a, b, 1987) and Lennert et al. (1991) to provide figures of 5130 (4/1980-3/1983), 917 (4/1983-3/1984), 232 (3/1984/1985) and 157 (4/1985-3/1986), 129 (4/1986-3/1987),90 (7-12 1990) and 34 (1991). In California in 1992 and 1993, Julian (1993, 1994) calculated that68 and 89 California sea lions died in the swordish/shark drift-net fishery, respectively. Miller etal. (1983) estimated that in the 1979/80 season, 7 California sea lions were killed incidentally inthe Klamath River gill-net fishery in northern California and 15 California sea lions died inrockfish gill nets.

Overall, Barlow et al. (1990) estimated that some 2000 - 4000 California sea lions have beentaken annually in California set net fisheries for halibut and angel sharks. Cranmore (1990)estimated that about 2250 sea lions are killed in California gill nets during a typical year. Perkinset al. (1992) gives figures of 3753 (1988/89), 2315 (Apr - Dec 1989), 2753 (1990) and 1865 (1991)California sea lions incidentally killed in California commercial gill net fisheries. Young et al.(1993) estimate that incidental mortalities in Washington, Oregon and California were 2983 in 1990and 2043 in 1991.

Incidental mortality of California sea lions have also been reported in other fisheries.Incidental mortality of sea lions in 1979/80 in California was estimated by Miller et al. (1983) tobe 20 in the purse seine net fishery for anchovy and mackerel, 10 in the purse seine fishery forsquid and a maximum of 300 seals in 1980 in the commercial salmon troll fishery. Brown (1988)noted that in the Yaquina Bay purse seine herring fishery, sea lions normally escape from netsthrough the bottom or over the cork line before it is closed. From 1973 to 1988, only a singleCalifornia sea lion was incidentally caught and died in foreign trawlers in the North Pacific andeastern Bering Sea (Barlow et al. 1990, Perez and Loughlin 1991) and low numbers of Californiasea lions were reported to be taken in Pacific trawl fisheries in Oregon (Mate 1980). Miller et al.(1983) estimated that 25 California sea lions were killed incidentally in the trawl fishery in the1979/80 season in California.

Northem Fur Seals

Northern fur seals die incidentally during gill net (rarely in inshore but more frequently inoffshore) and trawl fishing in coastal and offshore waters along the northwest coast of NorthAmerica (Mate 1980, O'Hara et al. 1986, Cranmore 1990, Loughlin 1991). Occasionally northernfur seals are taken during salmon drift netting (Everitt and Beach 1982). During observed sets in

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1990 in Prince Williams Sound and South Unimalc, Alaska, 2 northern fur seals were entangled butbroke free from drift and set nets for salmon (Wynne 1991). Young et al (1993) estimate that thetotal number of incidental deaths of northern fur seals in coastal Alaska, Washington, Oregon andCalifornia were 4 and 7 in 1990 and 1991 respectively. Around 200 northern fur seals are takenin offshore salmon drift nets per year, based on observations in the EEZ of the US (Cranmore1988).

In a total of 45 sets of squid nets on Canadian research cruises using commercial size meshbetween 1986 and 1989 a single northern fur seal was entrapped but it was released alive (Bernard1986, LeBrasseur et al. 1987, 1988 and McKinnell et al. 1989). Between 1983 and 1987, Jamiesonand Heritage (1988) and Barlow et al. (in press) report that a single northern fur seal was caughtin Canadian offshore squid fishery trials in 1985 and 1987. In 1986 and 1987 US observersrecorded a total of 30 (22 lcilled) northern fur seals caught in squid nets (Jones 1988).

Observers often recorded no incidental captures between 1973 and 1988 on foreign trawlersin the North Pacific and eastern Bering Sea and generally no more than 5 northern fur sealsannually, except in 1984 when 17 were caught (Perez and Loughlin 1991, Loughlin et al. 1983).NRC (1989) reports that foreign trawlers have taken an estimated 192 seals over the period 1978 -1987, with 45 taken in 1978, declining to zero in 1987. In the joint-venture fishery only 24 were

taken between 1984 and 1987; in the domestic trawl fishery, 11 were caught between 1985 and1987 (NRC 1989).

Guadelupe Fur Seals

Guadelupe fur seals die as a result of line fishing. Two out of six Guadelupe fur sealsrecovered in central California were found to have wounds from fishing hooks (Hanni et al. 1993).

Eastern Pacific Harbour Seals

Harbour seals are taken incidentally during gill net and trawl fishing in areas off Alaska, andsouthwards to California (eg, Miller 1981, Montgomery 1986, Herrick and Hanan 1988, Cranmore1990, Hanan et al. 1993, Reijnders et al. 1993). Young et al. (1993) estimated that the totalincidental mortality in Alaska, Washington, Oregon and California was 1153 in 1990 and 979 in1991.

In the Copper River salmon net fisheries in the spring of 1978, 117 harbour seals were caughtand died (Matkin and Fay 1980). In the Coghill District, 28 harbour seals were captured and died,and 24 were released alive (Matkin and Fay 1980). In the Copper-Bering fishery in the autumn of1978, 44 harbour seals were captured; 11 died and 33 were released alive (Maticin and Fay 1980).In 15 weeks of survey in 1988 only a single harbour seal pup incidentally drowned in 387 salmondrift net sets in the Copper River delta (Wynne 1990). Wynne (1991) estimated that 36 harbourseals died in the Prince William Sound driftnet and set net fisheries for salmon in 1990 and Wynneet al. (1992) estimated that 20 harbour seals dyed in this fishery in 1991. For 1990, preliminarydata indicate that only two harbour seals were taken in 3150 observed sets of Prince William Sound

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drift and set-nets for salmon. Fishermen reported the catch of only one harbour seal in gill netfisheries in southeastern Alaska; 5 harbour seals caught incidentally and a further 4 reported killedin set nets in Yakutat (Barlow et al. 1990, in press). Logbook data for 1990-1991 record 25 harbourseals deaths in the Bristol Bay, Alaska set and drift net fisheries for salmon. There were incidentaldeaths in 1990 and 1991 in the Cook Inlet, Alaska driftnet and set net fishery for salmon (Barlowet al. in press)

In the Columbia River in Oregon/Washington, Everitt and Beach (1982) reported that at least51 harbour seals died in the salmon gill net fishery in 1980 and 4 died or were Idlled in 1981. Laterit was estimated that 193, 334 and 210 harbour seals were incidentally caught in 1980, 1981 and1982. Captures for the mid-1980's were estimated at 350 to 400 seals per year (Geiger 1985,O'Hara et al. 1986, NMFS 1992, Boveng 1988b, Beach et al. 1985). Fishermen reported that 24harbour seals were taken in the Washington salmon gill net fisheries in 1989 (Gearin et al. 1990,Barlow et al. in press). In inland waters of Washington, an estimated 50 to 100 harbour seals areincidentally killed in the Puget Sound gill net fisheries per year (Boveng 1988b). During 1984 inthe Columbia River sturgeon gill net fishery, 5 harbour seals were observed incidentally caught andkilled (Brown 1988).

In 1980, DeMaster et al. (1985) reported that 132 seals were caught and killed in gill nets,in California. A later estimate by Barlow et al. 1990, is that in California 1000 - 2000 harbour sealmortalities occur in the inshore net fishery and others die in mainly gill net fisheries.

In the Klamath River drainage in northern California, 18 out of 29 harbour seals recoveredfrom the salmon gill net fishery in 1979/1980 were known to have died, a further 4 were releasedalive in (Herder 1983, Miller et al. 1983). Off the California coast, Miller et al. (1983) estimatedthat the ocean gill net fisheries took about 95 harbour seals in 1980.

Wild (1985, 1986, 1987) reported 22 harbour seals from a total of 372 gill and trammel nethauls in central California, during 1984, 36 from 419 net hauls during 1985, and 61 from 514 nethauls during 1986. From 1980 to 1989, observations of gill and trammel net hauls for halibut incentral California recorded between zero and 71 harbour seal taken annually for a total of 249 sealsfrom 1764 hauls (Wild 1990). For southern California, Collins et al. (1984, 1985, 1986) reportedincidental catches of harbour seals in monitored gill and trammel set nets for halibut, soupfin shark,angel shark and white seabass, from two to 17 during the years 1983 to 1985. In the drift gill netfishery for swordfish and sharks, harbour seal mortality was reported as zero (4/1980 - 3/1985),158 (1985/86), 90(1986/87), 23 (1990) and zero (1991-1993) (Diamond et al. 1987, Lennert et al.1991, Barlow et al. in press). Overall in California, incidental harbour seal mortality in gill net andtrammel net fisheries was 130 (1980/81), 834 (1983/84), 1138 (1984/85), 1886 (1985/86), 2028(1986/87), 903 (1987/88), 392 (1990), 559 (1991), 1136 (1992) and 480 (1993) (Miller et al. 1983,Hanan et al. 1985, 1988, 1989, Hanan and Diamond 1989, Barlow et al. 1990, in press, Lennertet al. 1991, Hanan 1992, Julian 1993, 1994, Konno in press).

On foreign trawlers in the North Pacific and eastern Bering Sea, observers recorded anincidental catch of a single harbour seal in 1977, 1979, 1981 and 1982 after which the number

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increased, reaching 9 in 1985 and then decreasing again until 1988 (Loughlin et al 1983, Perez andLoughlin 1991). The total incidental kill of harbour seals in commercial fisheries off Alaska wasestimated at 1440 in domestic fisheries and 289 from foreign fisheries in 1978 (NMFS 1978), andat 2800 in both fisheries in 1979 (Brooks 1979). The annual catches of harbour seals in trawlfisheries have been estimated as between zero and 20 seals for the period 1979 to 1987, for a totalof 85 deaths (NRC 1989).

Larga Seal

Small numbers of Larga seals are taken during gill net and trawl fishing in Alaska andoffshore areas (eg, Lentfer 1988). Young et al. (1993) estimated that the number of incidentaldeaths of Larga seals in fisheries in Alaska was 3 in both 1990 and 1991. In set and drift netfisheries for salmon in Bristol Bay Alaska, logbook data for 1990-1991 record 2 Larga seals deaths(Barlow et al. in press).

On foreign trawlers in the North Pacific and eastern Bering Sea, observers recorded incidentalcaptures from 1973 to 1988 of a single Larga seal in 1983, 1987 and 1988 (Barlow et al. 1990,Perez and Loughlin 1991) although between 1978 and 1986, an estimated 2 - 22 seals have beentaken by foreign and joint-venture demersal fisheries (Cranmore 1990).

Arctic Ringed Seals

Few Arctic ringed seals are taken by gill net and trawl fishing in offshore regions (eg, Kelly1988b), Young et al. (1993) reported that none were lcilled in 1990 and 1991. Small numbers ofArctic ringed seals are taken in high-seas salmon research driftnets (Ito 1986, FAJ 1986, 1987,1988). On foreign trawlers in the North Pacific and eastern Bering Sea, observers recordedincidental captures and from 1973 to 1988, noted that a single Arctic ringed seal was caught in 1986and 1988 (Perez and Loughlin 1991) although incidental captures of 17 Arctic ringed seals havebeen reported in the Alaskan pollock trawl fishery (Barlow et al. 1990).

Ribbon Seal

Few ribbon seals are taken incidentally in trawl fishing in offshore areas (Kelly 1988a,Reijnders et al. 1993). Young et al. (1993) reports that none were killed or injured in 1990 and1991. On foreign trawlers in the North Pacific and eastern Bering Sea since 1973, a single ribbonseal was caught in 1978 and 1979 (Perez and Loughlin 1991). Two ribbon seals were taken in 1982,5 in 1983, 7 in 1984 and 1 in 1985 and none until 1988 (Perez and Loughlin 1991). NRC (1989)provides estimates of 30 in 1978, 5 in 1982, 7 in 1983 and 6 in 1984 ribbon seals (live released anddecomposed animals excluded) taken in foreign fisheries, with none taken in the other years.

Pacific Bearded Seal

Small numbers of Pacific bearded seals are taken in gill net and trawl fishing in Alaska andoffshore regions. Logbook data for 1990-1991 show deaths of 14 bearded seals in the Bristol Bay

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set and drift net fisheries for salmon (Barlow et al. in press). Between 1978 and 1988 there havebeen fewer than five reported incidental takes of bearded seals in foreign commercial fishingactivities in the Bering Sea (NMFS 1992). Four bearded seals were reported taken in the Alaslcantrawl fishery for pollock (Barlow et al 1990) - one caught in 1985, two in 1986 and one in 1988(Perez and Loughlin 1991). In 1991 three bearded seals were observed caught in domestic Alaslcantrawl fisheries and the total number of incidental ldlls in Alaskan fisheries is estimated to be 1 in1990 and 37 in 1991 (Young et al. 1993).

Hawaiian Monk Seals

Small numbers of monk seals are caught incidentally during gill net and trap fishing andduring longline fishing (Reijnders et al. 1993).

One monk seal was reported to have died in a gill net near Poipu, Kauai in 1976 (Nitta 1990),another in a lobster trap line near Necker Island in 1986 (Nitta 1990, Ragen 1993) and one in a fishtrap (Kenyon 1981). Nitta (1990) reports that there is circumstantial evidence that Hawaiian monkseals may have died in the broadbill swordfish longline fishery in the northwestern Hawaiian Islandsalthough no mortalities have been confirmed. Various harmful injuries relating to fishing operationshave been noted: hooks from longline gear embedded in their skins or mouths (Reddy and Griffith1988, Nitta 1990, Woodley and Lavigne 1991, MMC 1993, Ragen 1993, Young et al. 1993),probable propeller wounds (Craig et al. 1993, Ragen 1993) and unusual head or lateral injuries(Ragen 1993, Young et al. 1993)

Northern Elephant Seals

Small numbers of northern elephant seals are incidentally taken in gill net and trawl fishingin coastal and offshore waters (Condit and Le Boeuf 1984, Collins et al. 1984, 1985, 1986,Diamond et al. 1986a, b, Herrick and Hanan 1988, NMFS 1992) and Boveng (1988a) suggests thatthis is probably a result of elephant seals feeding offshore in deep water. Young et al. (1993)estimated that the total mortality of northern elephant seals for fisheries in Alaska, Washington,Oregon and California was 286 in 1990 and 137 in 1991.

Wild (1985, 1986, 1987) reported the incidental take of 2 elephant seals in 1984, 4 in 1985and 5 in 1986 in halibut set nets in Half Moon and Bodega Bays of north-central California.Between 1980 and 1989 Wild (1990) reported an annual take of zero to 15 elephant seals inobserved hauls of gill and trammel nets for California halibut and white croaker in centralCalifornia (Monterey to Bodega Bay area). An incidental catch of one elephant seal was recordedfrom 145 observed hauls of set-nets for halibut and angel sharks off California in 1990 (Barlow

et al. 1990) while Lennert et al. (1991) estimate that the number of mortalities rates of northernelephant seals in set nets for halibut and Pacific angel sharks in California was 144 in six-monthsin 1990. Barlow et al. (in press) report that 26 elephant seals were taken in the California set netfishery for halibut and angel sharks in 1991 and Perkins et al. (1992) estimate that 137 elephantseals died during 1991. In 1992 and 1993 in Julian (1993, 1994) calculated that 51 and 71 northernelephant seals respectively died in the Californian halibut set-net fishery. Although there are no

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data, it has been suggested that elephant seals are likely to be taken by drift gill net vessels inMexico (Barlow et al. 1993).

In the drift shark/swordfish drift gill net fishery in California, Diamond et al. (1987) reportedcatches of 308 elephant seals in 1983, none in 1984 and 300 in 1985. Lennert et al. (1991) estimatethat the mortalities of northern elephant seals in these nets was 90 in six-months of 1990. ThereafterBarlow et al. (in press) report that 110 were taken in 1991. In 1992 and 1993 Julian (1993, 1994)calculated that 114 and 103 northern elephant seals died in the swordish/shark drift-net fishery,respectively.

Miller et al. (1983) estimated that 25 northern elephant seals were taken in ocean gill netsduring 1980 off the coast of southern California. Fishermen reported one northern elephant sealtalcen in the salmon drift net fishery in the southeastern Alaska (Barlow et al. 1990, in press).An incidental catch of three elephant seals (one in 1976 and two in 1982) has been documented forforeign trawlers in the eastern North Pacific Ocean and eastern Bering Sea (Loughlin et al. 1983,Barlow et al. 1990, Perez and Loughlin 1991).

Pacific Walrus

Walruses are taken in offshore active nets (trawls). Young et al. (1993) estimate that 5 and6 were killed in 1990 and 1991 in Alaska, respectively. Observers, on foreign trawlers in the NorthPacific and eastern Bering Sea, observers recorded incidental captures from 1973 to 1988 of singlewalruses in 1977 and 1980, after which the number increased to 20 in 1985 and 1987 and 16 in1988 (Perez and Loughlin 1991). Estimated annual catches in the joint-venture and domestic trawlfisheries were 3-40 animals between 1983 and 1987 and 2-51 animals between 1985 and 1987 (NRC1989). The NMFS has recorded a direct catch of 76 walruses in trawls (Barlow et al. 1990). Inforeign and joint-venture groundfish fisheries between 1977 and 1988, 40 walruses were caught(NMFS 1992). Walruses also have some interactions with the yellowfin sole trawl fishery (Younget al. 1993).

Unidentified Pinnipeds

Various unidentified pinnipecls have been recorded as taken in gill net and trawl fishing incoastal and offshore waters. Fishermen have reported one sea lion as taken in the salmon drift netfishery in southeastern Alaska (Barlow et al. in press). In California, Julian (1993, 1994) calculatedthat 59 and 43 unidentified pinnipeds died in the halibut set net fishery in 1992 and 1993,respectively and 63 unidentified sea lions died in 1992 in the halibut set-net fishery.

On foreign trawlers in the North Pacific and eastern Bering Sea, observers recorded incidentalcaptures from 1973 to 1988, 25 unidentified pinnipeds were recorded in 1973; from 1982 fewerthan 4 annually were recorded (Perez and Loughlin 1991).

2.3.2 Deliberate Killing

Steller's Sea Lions

Steller's sea lions are killed by intentional and indiscriminate shooting (Mate and Gentry1979, Loughlin 1991, Reijnders et al. 1993, Barlow et al. in press). In the Copper River salmonnet fisheries in the spring of 1978, 305 Steller's sea lions were shot in the Coghill district and 20died (Matkin and Fay 1980). In 15 weeks of survey in 1988, only 3 Steller's sea lions were killed(Wynne 1990). Beach surveys in the Copper River showed 10 Steller's sea lion to have died fromgunshot wounds and a further 6 to have suspected gunshot injuries in 1988. During 1989 definitegunshot wounds were found on 4 animals and a further one had a suspected gunshot wound (Wynne1990).

California Sea Lions

California sea lions are shot or clubbed during fishing operations (Everitt and Beach 1982).Lowry and Folk (1987) reported that 11% of 121 fresh or moderately decomposed dead strandingsexamined between October 1980 and September 1983 in southern California, and 82% of 11 deadstrandings at Santa Catalina Island, had gunshot wounds assumed to have been inflicted byfishermen. Lowry et al. (1992) report that 3 live stranded California sea lions in 1988), 1 in 1990and 1 in 1991 were treated in San Diego and were presumed to have been shot by fishermen.

Herder (1983) reported that 5 of the 7 California sea lion mortalities were caused by thelamprey eel seine fishery. Miller (1981) report that in 1979 during salmon fishing operations onlya single California sea lion was known to be shot but that more animals than this are probably shot.Miller et al. (1983) report that 200 - 300 animals were shot by commercial salmon troll fishermenin 1980 attempting to protect their gear or catch on the California coast.

Northern Fur Seals

Northern fur seals are known to be shot or clubbed (Everitt and Beach 1982),

Guadelupe Fur Seal

Reijnders et al. (1993) note that lobster fishermen possibly kill Guadelupe fur seals,presumably for bait because there are no documented cases of these fur seals interacting with theirfishing operations.

Eastern Atlantic Harbour Seals

Harbour seals are shot or clubbed during fishing operations in Alaska and California (Herder1983, NMFS 1992). In the Copper River salmon net fisheries, 73 harbour seals were shot in thespring of 1978 and 111 in the autumn of 1978, while in the Coghill district 119 harbour seals werekilled (Matkin and Fay 1980). In 387 salmon drift net sets in 1988 and 1989 in the Copper River

19

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Delta, 2 harbour seals were observed to be shot and killed by fishermen defending their catch andgear (Wynne 1990). During beach surveys in the Copper River, 6 harbour seals had suspectedgunshot injuries in 1988 and 2 harbour seals showed definite or suspected gunshot wounds in 1989(Wynne 1990).

Hawaiian Monk Seals

A survey conducted at French Frigate Shoals in late January 1991 recorded five seals withhead injuries indicating they had been hooked or clubbed (Woodley and Lavigne 1991).

Northern Elephant Seals

Some northern elephant seals are killed by fishermen (Reijnders et al. 1993).

2.4 Mitigation Measures

Acoustic scare systems have been tried but while they may be initially successful theireffectiveness does not appear to be long-term (DeMaster et al. 1982, Everitt and Beach 1982, Anon1983, Mate and Miller 1983, Awbrey and Thomas, 1987, Geiger and Jeffries 1987, Greenke andvanSlyke 1987, Greenlaw 1987, Hanan and Scholl 1987a, b, Harvey et al. 1987, Mate et al. 1987,Rivinus 1987, Scholl 1987, Scholl and Hanan 1987a, b). Mate and Harvey (1987) documented theproblems of using acoustic devices and the factors that need to be considered when designingacoustical methods, namely the temperature, salinity and depth of the water, background noise suchas water turbulence, rain or man-made noises, bottom topography which affects sound propagation,water surface reflections, bottom reflections and the location of the subject relative to the soundsource.

Other mitigation measures that have been discussed are the use of killer whale sounds, crackershells, seal bombs, flashing lights, chemical deterrents and lethal methods, but all have problems,amongst which are the general problems with acoustic methods, habituation of seals to the methods,association of seals with fish occurrence resulting in the acoustic signal attracting seals, the fact thatthe methods frighten the fish, public safety and reaction in the case of lethal methods (Hanan 1985,Mate and Harvey 1987) and cost (for example a Canadian halibut boat reportedly spent $4000annually on materials, including dynamite, to deter and kill sea lions) (Anon 1978b).

Tests on captive California sea lions to see if they would develop taste aversion to fishcontaminated with lithium chloride proved to be promising (Kuljis 1985) and field trials were to becontinued (Montgomery 1986) and assessed in conjunction with auditory signals to keep the negativestimulus and reduce habituation (Mate and Harvey 1987) while bearing in mind behaviourialconditioning (Pryor 1987).

DeMaster and Sisson (1992) note that although California sea lions cause financial losses tofishermen through operational interactions, reducing the general population of sea lions will do little

21

to mitigate these interactions. Only changes in the local abundance of sea lions or the developmentof methods to frighten them away from fishing grounds will address this problem (DeMaster andSisson 1992).

Montgomery (1986) suggested that studies should be done to identify factors (eg, soalc timeof nets) that may be causing, or contributing to, the incidental take of harbour seals and toinvestigate alternative fishing gear and practices and the use of acoustic signals paired withshooting, loud sounds or other adverse stimuli and disturbance experiments. In Alaska, fishermenfound that the Steller's sea lions' habit of chewing marker buoys could be countered by the use ofa solid styrofoam float (Mate 1980).

DeMaster et al. (1982) note that most fishermen seem to consider losses caused by marinemammals as an overhead or they simply avoid where seals congregate. Many fishermen in thepartyboat fishery in California note that harming sea lions in an effort to improve fishing willprobably alienate, rather than satisfy, their clients (Scholl 1983).

3. NOR WEST ATLANTIC OCEAN

3.1 Species Distribution

This area includes the east coast of North America, the east portion of the north coast of NorthAmerica from 100°N, the west coast of Greenland and the small portion of the east coast of SouthAmerica that falls above the equator (FAO areas 21 and 31 and part of 18 and 41). Sevenspecies/subspecies of "true seal and a subspecies of walrus are found this area.

The grey seal population of 80 000 - 110 000 in 1987 on the east coast of Canada isincreasing (Zwanenburg and Bowen 1990). Western Atlantic harbour seals occur along the northeastcoast of the USA, the east coast of Canada, the Canadian arctic and the west coast of Greenlandwith a population size of at least 40 000 to 100 000 (Reijnders et al. 1993). The Ungava seal isfound in lakes in Quebec, eastern Canada and has a population size of possibly 200 - 600individuals (Power and Gregoire 1978) and is listed by the IUCN Red List as "Insufficientlyknown". Harp seals are found on the east coast of Canada, the Canadian arctic and Greenland andhave a population of 2.4-4.2 million animals (CAFSAC 1991). The Arctic ringed seal is found onthe east coast of Canada, the Canadian arctic and the west coast of Greenland and comprises partof the total population of 6-7 million animals (Reijnders et al. 1993). Hooded seals are found onthe east coast of Canada, the Canadian arctic and Greenland and have a population in that area of325 000 (Reijnders et al. 1993). Atlantic bearded seals are found on the Canadian east coast, theCanadian arctic and Greenland but no population size estimates are available (Reijnders et al. 1993).The Atlantic walrus is found in the east Canadian arctic and west Greenland with a population sizein that area estimated at a few thousand animals (Fay et al. 1990).


Three of the 8 pinnipeds found in this area (grey, Western Atlantic harbour and harp seals)have been reported to affect all forms of fishing in different areas - passive and active net, trap andline fishing and fish farming.

3.2.1 Depredation


Depredation by grey, harbour and harp seals occurs during gill netting in Canadian watersand lobster trap fishing on the U.S.A. coast. In the Gulf of St Lawrence, seals, probably harpseals, feed on smelts caught in set nets when ice is scarce (Malouf 1986). In the southern part ofthe Gulf of St Lawrence, and in estuaries in New Brunswick, seals, and in particular grey seals,"rob" salmon gill nets so that the nets are not be watched continually and often retrieved at night,though this is no longer such an important problem because reductions in salmon fishing (Mansfieldand Beck 1977). In the Bay of Fundy grey and harbour seals are reported to depredate gill-nettedfish and interfere with the Atlantic herring weir fishery (Malouf 1986, Colbourne and Terhune1991). Salmon trap fishermen in Nova Scotia estimated losses of 30-45% of their catch to seals andtraps cannot be used near grey seal haul-outs (Mansfield and Beck 1977). Grey seals enter traps setfor mackerel and herring and mutilate large numbers of fish (Mansfield and Beck 1977). On thenortheast coast of the U.S.A., fishermen report that harbour seals eat lobsters taken from traps(Malouf 1986).

Active Net Fishing

Pemberton et al. (1994) assessed depredation during trawling off Newfoundland by harp sealsand to a lesser extent by hooded seals to be less that 0.002% of the catch although seals do takenfish spilled from the net.

Passive Line Fishing

In New Brunswick, grey and/or harbour seals, eat fish from longlines often only leaving thehead attached to the hook (Malouf 1986).

Active Line Fishing

Along the Canadian coast, grey and/or harbour seals, take fish from all types of hook and linegear such as trolls and sports gear (Malouf 1986).

Fish Farming

In 1983/84 grey seals attacked fish at about 75% of the aquaculture cage operations in theBay of Fundy (Malouf 1986).

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3.2.2 Gear Damage


Grey seals and to a lesser extent harbour and harp seals, damage or result in the loss of gillnets and lobster traps in a number of areas on the Canadian coastline (eg, Reijnders et al. 1993)though in the southern part of the Gulf of St Lawrence this is no longer such an important problembecause of reductions in salmon fishing (Mansfield and Beck 1977).

Mansfield and Beck (1977) estimated from questionnaires and interviews in Nova Scotia in1975, that individual fishermen could suffer losses to grey seals of gear (drift and set gill nets, trapnets and lobster traps) to the value of $1 000 in a single year, but losses averaged $300 perfisherman. Zwanenburg and Beck (1981) from a survey in Nova Scotia in 1978, reported that themaximum damage caused by seals to gear amounted to $105 per fisherman and varied greatly alongthe coast from no losses to $308 per fisherman.

Calculations by Malouf (1986) from estimates in Farmer and Billard (1984) showed that repairand replacement costs to fixed gear as a result of seals in Nova Scotia in 1983 amounted to anaverage of $236 per fisherman per year and individual damage estimates were reported formackerel-herring gill nets ($35 272), groundfish gill nets ($8 072), wooden lobster traps ($23 945)and fish traps ($2 916). Total losses as a result of gear damage in the mid-1980's were calculatedas $1 241 000 but given various factors that affect these calculations, it was concluded that damagein the Nova Scotia region could be millions of dollars or higher per year (Malouf 1986).

Malouf (1986) report that as many as 75-100 bait bags were removed from lobster traps in thevicinity of seal colonies in a single day of fishing and that fishermen had lost up to 1500 bait bagsin a season in Nova Scotia.

Fish Farming

In 1983-1984 grey seals made holes in the cage twine at about 75% aquaculture cageoperations in the Bay of Fundy (Malouf 1986).



Grey seals enter traps set for mackerel and herring and sometimes drive the fish through thetrap opening into the open sea (Mansfield and Beck 1977). They also open lobster traps, force theirway into them and steal bait, allowing the lobsters to escape and preventing further catches untilthe trap is baited and re-set (Mansfield and Beck 1977, Malouf 1986).

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3.3 De ental Effects on Seals

All of the pinnipecls found in this area (grey, Western Atlantic harbour, harp, Arctic ringed,hooded, Atlantic bearded and the Atlantic walrus, except the freshwater Ungava seal), areincidentally or deliberately killed during passive and active net fishing and passive line fishing.


Grey Seals

Small numbers of grey seals are lcnown to be caught incidentally in gill net and trawl fishingin various areas along the Canadian and U.S.A coast (eg, Gilbert and Wynne 1988, Lien et al.1989, Woodley and Lavigne 1991, Reijnders et al. 1993). In groundfish fisheries on the north-eastcoast of the U.S.A. 4 grey seals were caught in 1984 (Gilbert and Wynne 1985) and Young et al.(1993) estimate that a total of 4 and 3 grey seals were killed in fisheries on the east coast of theU.S.A in 1990 and 1991, respectively.

Western Atlantic Harbour Seals

Harbour seals are taken during gill net and trap fishing trawl and purse-seine fishing andlonglines fishing in Canada and the U.S.A.

In Newfoundland and Labrador ,harbour seals have been taken incidentally in inshore waters,particularly in cod gill nets (86% of the take) but also in salmon-gill nets (10%) and cod traps (4%)(Lien et al. 1988a, 1989). Piatt and Nettleship (1987) estimated that 29 harbour seals were caughtper year mostly in relatively shallow set (<30m) cod gill-nets in eastern Newfoundland.

In the U.S.A., an average of 22 harbour seals are entangled annually by 17 groundfish gillnet fishermen in the Gulf of Maine; all are apparently young of the year (Gilbert and Wynne 1988).Other fishing operations in Maine, although rarely, herring purse seines, halibut tub trawls, lobstertraps and mackerel gill nets and longlines (Gilbert and Wynne 1985, 1988, Cranmore 1988) takeharbour seals. Young et al. (1993) estimated that 617 harbour seals were Idlleci in 1990 and 257were killed in 1991 in fisheries on the east coast of the U.S.A.

Harp Seals

Harp seals are taken during gill net and trawl fishing on the coasts of Canada and Greenland.Peak entrapments of harp seals in groundfish gill nets occur in May / June along the west and southcoasts of Newfoundland when seals are migrating northward (Piatt and Nettleship 1987, Lien et al.1988a). From a survey of the southeast coast of Newfoundland during 1981-84, 746 harp seals peryear were estimated to be taken in deep-set (>20m) cod and flounder gill nets, set up to 100 kmfrom shore in eastern Newfoundland (Piatt and Nettleship 1987).

Malouf (1986) reported that the incidental kill of harp seals around Newfoundland and

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25

Labrador rose from 1000 annually between 1979-82 to around 5000 in 1984. In 1984, substantialnumbers of harp seals were caught in various areas (Lien et al. 1984) and Malouf (1986) reportedanecdotal evidence of one fisherman catching 38 harp seals in his nets in one day. Existing reportsare thought to considerably underestimate numbers of harp seals caught in groundfish gill nets,ranging from up to 68 per day in June and 20-30 per day in July (Lien et al. 1984). In 1985,reports from Newfoundland indicted "many" harp seals were entrapped, particularly young seals,and the perception of fishermen was that this was higher than in previous years (Lien et al. 1985).

In 1987 two reports were received at midyear of captures of 11 to 25 seals per 100 nets setand a similar number suggested as having been taken in the 3-4 years previously in the Bonne Bayarea (Lien et al. 1987). A number of fishermen indicated that perhaps 500 to 2000 young harp sealswere taken in the spring groundfish gill net fishery in Old Fort Quebec in the Gulf of St Lawrencein the spring of 1987 (Lien et al. 1987, Lien 1988). It is estimated that during 1986 and 1987,catches were around 700 per year (Lien et al. 1988a). In 1988 it was estimated that 10 700 seals,mostly the young of the year, were taken primarily in gill nets on the west coast of Newfoundlandand in some areas, 80-90 seals were reported as by-catch each day over two weeks (Lien et al.1988a, b). Captures were reported to have remained high in 1989 (Lien et al. 1990a) and incidentalcatches of harp seals appear to be increasing in the inshore coastal waters of Newfoundland,although it is difficult to quantify inshore fishing effort (Lien et al. 1989). Off the west coast ofGreenland Christensen and Lear (1977) report that harp seals are caught incidentally in salmon gillnets.

During cod trawling off north-east Newfoundland, Pemberton et al. (1994) reported 8 harpseals caught during 14 trawls in 450 fathoms of water, 2 of which were dead. Two of those alivewere females, the rest were male (Pemberton et al. 1994).

Arctic Ringed Seals

Arctic ringed seals are taken during gill net fishing in Canada and Greenland. In southernLabrador several fishermen reported taking "dozens" of Arctic ringed seals in inshore nets in 1985(Lien et al. 1985) and the incidental capture of Arctic ringed seals in inshore nets was also reportedduring 1990 (Lien et al. 1990b). In Greenland, salmon gill nets have been reported to take Arcticringed seals (Christensen and Lear 1977).

Hooded Seals

Very few hooded seals are caught in gill nets in Newfoundland and Labrador (Lien et al.1989). Piatt and Nettleship (1987) documented the incidental take of four hooded seals in cod gillnets off southe,ast Newfoundland between 1981 and 1984 and Lien et al. (1990b) reported twohooded seals in inshore nets in 1990.

Atlantic Bearded Seals

Christensen and Lear (1977) reported that there were incidental catches of bearded seals in

salmon gill nets off Greenland.

Walrus

In the Newfoundland and Labrador region, a walrus was reported to have been caught in aninshore gill net during 1990 (Lien et al. 1990b).


Grey seals are lcnown to be shot by fishermen (Reijnders et al. 1993). Grey seals, and to alesser extent harbour and harp seals, were reported to be controlled by shooting near salmon netswhen they were considered to be a problem (Malouf 1986).


In Canada lobster fishermen have modified their gear to minimise damage from seals (Malouf1986). They put boxes over the bait and used smaller rings to make it difficult for seals to get theirheads .into the trap, although this may have precluded catching "jumbo" lobsters (Farmer andBillard 1985). Salted bait was also reported to be less attractive to seals, thereby reducing sealdamage, but was also thought to be less attractive to lobsters (Malouf 1986). The introduction ofheavier twine for aquaculture cages was reported to reduce seal damage in New Brunswick (Malouf1986).

Pemberton et al. (1994) report that seal captures in trawls can be reduced dramatically if thenets are kept on deck and then shot to the bottom immediately on entering the water. A chute fromthe working deck to the gunwale was suggested as a method of allowing captured seals to leave thevessel quickly (Pemberton et al. 1994).

4. NORTIIE:ST ATLANTIC OCEAN

4.1 Regional Description

This area includes the east coast of Greenland, Iceland, Svalbard, western Europe, the UnitedKingdom, the west coast of Africa above the equator and the Baltic and Mediterranean Seas (FAOareas 27 and 37 and part of 34). There are 11 species/subspecies of "true" seals and a subspeciesof walrus in this area.

Grey seals occur around Britnin, Iceland, Norway, northwestern Russia and in the Baltic Seaand have a population in the area of between 104 700 and 106 700, which is probably increasing.Grey seals have significant problems related to incidental entanglement in the Baltic and White Seas(calculated from Reijnders et al. 1993). Eastern Atlantic harbour seAls occur in Iceland, Svalbad,Britain, northwestern Europe, Norway and into the Baltic with a population in the area of over 90

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The Caspian seal lives only in the Caspian Sea with a total population of 5(Reijnders et al. 1993) and is listed as "Vulnerable" in the 1993 IUCN Red list. Hin Gre,enland, Jan Mayen, Iceland and Svalbard with a population of 200(ICES/NAFO 1991). Atlantic bearded seals are found in the Atlantic arctic from Greenland throughto northwest Russia and its associated islands. There are no estimates of population size for thisarea (Reijnders et al. 1993). The Mediterranean monk seal is found in the Mediterranean Sea andalong the coastline and islands of Morocco. The population is estimated at 423 - 555 anddecreasing with incidental and deliberate mortality considered one of the main causes of thepopulation decline and a threat to the survival of the species (Reijnders et al. 1993). This speciesis listed as "Endangered" in the 1993 IUCN Red list. The Atlantic walrus is found in the arcticAtlantic from Greenland through to the northwestern Russian islands with a population estimatedat a few thousand animals (Fay et al. 1990).


Five of the 12 pinnipeds found in this area (grey, Eastern Atlantic harbour, harp,Mediterranean monk seals and possibly Baltic ringed seals) are reported to cause damage in variousareas to all of the different fishery types of fishing operation - passive net, traps and line fishingand active net and line fishing and fish farming.

4.2.1 Depredation


Grey, harbour, harp and monk seals, are regularly observed removing or damaging fish fromtrammel, tangle, stake, pound and bag nets and eel and lobster traps in different areas in Britain,

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000 (calculated from Reijnders et al. 1993). Incidental entanglement affects the population. Harpseals are found in the Atlantic arctic from Greenland to northwest Russia and its associated islandswith a population size in the area of between 600 000 and 900 I II seals (calculated from Reijnderset al. 1993). Incidental entanglement is a cause for concern.

Arctic ringed seals are found in the Atlantic arctic from Greenland through to northwest Russiaand its associated islands and in this region comprise a proportion of a total population of 6 - 7million animals (Reijnders et al. 1993). The Baltic ringed seal is found in the Baltic Sea with a totalpopulation of 5000 - 8000; it is probably increasing (Helle and Stenman 1990) although incidentalentanglement is a potential threat to the population (Reijnders et al. 1993). This subspecies is listedas "Vulnerable" in the 1993 IUCN Red list. The Saimaa seal is found in Lake Saimaa in Finlandand has a population size of 160-180 seals (Sipilia 1991), occasional entanglement is considered apossible threat to the population (Reijnders et al. 1993) and it is listed as "Endangered" in the 1993IUCN Red list. The Ladoga seal is found only in Lake Ladoga in Russia with a population size of10 500 - 12 500 and is probably increasing (Reijnders et al. 1993). It is listed as "Vulnerable" inthe 1993 IUCN Red list.

-600000ed seals occurin the region

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Ireland, Scandinavia and in the Mediterranean (eg, Hardy 1953, 1961, Mountford and Smith 1963,Hickling 1964, Bonner 1972, 1982, Lister-Kaye 1979, Harwood 1984). In Britain, damage ishighest in the early part of the salmon season when the larger and more valuable fish are running.The problem is attributed mostly to a small number of "rogue" seals which specialise in preyingon netted salmon (Parrish and Shearer 1977, Harwood 1991). Although the level of damage isvariable from place to place, it shows no apparent relationship between the proximity of the netsto known concentrations of seals and remained steady during 1965-76 although the grey sealpopulation doubled in size (Harwood and Greenwood 1985).

In Scotland in 1954, records kept by 2 firms on the River Tweed recorded losses of about£400 each due to seal-damaged salmon (Rae 1960). During the 1958 and 1959 seasons, an averageof 5% of salmon were damaged on the east coast of Scotland based on a study of fish sold in theAberdeen fish market (Rae 1960). Rae and Shearer (1965) found that in Scotland 24.5% of thesalmon in gill nets were damaged by seals. The sorts of wounds inflicted were reduced the valueof the salmon by 10-20% (Parrish and Shearer 1977). Anon (1975c) reports that one Scottishsalmon found 9.7% of their salmon bitten or clawed by seals in 1974 and it was felt that aconsiderable number of salmon was completely removed by seals. Grey seals on the Scottish coastwere estimated to take or damage, 3.0% of fish in bag/stake nets (Greenwood 1981).

In north-east England Potter and Swain (1979) investigated grey seal predation in the drift netfishery for salmon and estimated that seals removed 3-10% of the fish caught, averaging about 5%of all fish caught, and damage,d a further 1.4%, although there was considerable variability throughthe fishing season and from site to site. This represented a loss to salmon fishermen of about $30000 in 1977 (Potter and Swain 1979). In northeast England grey seals were estimated to have takenor damaged 2.3% of fish in bag/stake nets (Greenwood 1981). In the inshore whitefish set netfishery damage by month in a northern area of northeast England by grey seals was estimated tovary between 2.5% and 13.7% and between 0 and 6.7% in the southern area, varying overallbetween 0% and 21% but averaging about 5% annually, causing an estimated loss of approximately£16 000 (Heap et al. 1986).

Seals steal or mutilate fish in trammel nets, remove bait or fish from lobster pots and removeor damage fish from the wreck net fisheries for cod (Northridge 1988, Harwood 1991). In theMinch damage was estimated at 10% of the catch cod in the period 1958-1960 (Rae 1960). Largescale damage by seals on cod caught in nets on the British coast was reported by Rae (1969). Hecites an example from 1969 of 24 boxes out of 72 being unmarketable, 10 out of 52 boxes thrownoverboard because of seal-damage, and a further 6 boxes being marketable but at a lower marketprice. Harbour seals damage catches in the small herring drift net fishery off southeast England,but although seals bite the heads off herring in drift nets, the low value of the individual fish doesnot make this a major economic problem (Northridge 1988).

In Ireland during a two-week study in the draft net fishery in Ballytsodare Bay, 16.8% ofsalmon were recorded damaged (Anon 1980). On the south coast of Ireland in 1992, 31% of fishcaught in tangle nets were damaged by grey seals; the damage was typically the loss of a tail.Damage varied monthly with less damage offshore (>5 miles) than inshore (Collins et al. 1993).

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Seal-damage recorded from auction halls in Ireland varied from none in Kenmare, 0.66% in Galwayto 1.2% of the catch in north Mayo. These are underestimates because they excluded heads orpartially eaten fish (Anon 1980). At midyear in 1981, examination of salmon catches in GalwayBay showed 25.7% to 44.5% of salmon to be damaged by harbour seals (Anon 1981). Greyand, more extensively, harbour seals, were responsible for damage to salmon in gill net fisherieson the west coast of Ireland, ranging from 18.5% (1979) to 44.5% (1981) in Galway Bay, and7.5% (1980) to 9.8% (1981) of the catch in Sligo Bay (McCarthy 1985).

ICES (1979) reported that since 1964, the estimated damage to entrapped salmon by greyseals was 3-5%, and grey seals were seen to talce at least 2.3% of driftnet catches.

Grey, harbour and harp seals are known to eat salmon from nets in Sweden (Soderberg 1975),Finland (Stenman 1978), Norway (Bjorge et al. 1981, ICES 1992b) and Denmark (Hansen 1987).In Finland, Stenman (1978) found that during 1974-76, up to 60% of netted salmon were damaged.In Norwegian coastal waters, damage to salmon catches by grey or harbour seals was estimated byfishermen to vary between 5-25% with an average of about 15% (Bjorge et al. 1981). In Norway,the value of catches lost from gill nets attributable to harp seals was estimated at N.Kr 610 lOI in1979 and N.Kr 490 00 in 1980 (Bjorge et al. 1981). Nilssen et al. (1990, 1992) report that inJanuary 1986, 2.2-26%, (average 8.4%) of cod in gill nets in northern Norway may have beendamaged by harp seals, with usually the ventral soft parts of large fish being taken, including theliver and intestines. However, Nilssen et al. (1990, 1992) indicate that during the winter codfisheries from 1989 to 1991 no fish were damaged. In Denmark harbour seals take or damage fishfrom inshore pound and gill nets and damage eels in traps in areas where there are no crabs becauseeels make no attempt to escape from the trap in the presence of crabs and therefore are lessaccessible to seals (Hansen 1987).

Monk seals are reported to talce fish from fishing nets (Boulva 1979).

Active Net Fishing

In Britain grey or/and harbour seals, are said to remove or bite fish through the cod-end oftrawls on occasion and are presumed to remove or bite fish in seine nets (Northridge 1988).


In some places in Britain, grey and/or harbour seals, are reported to remove bait or fish fromlonglines (Rae 1960, Anon 1975c, Bonner 1982, Northridge 1988).

Active Line Fishing

Grey seals and possibly harp and ringed seals depredate fish from lines in Britain andScandinavia. On the English and Scottish coasts, grey and possibly harbour seals, strip bait fromhooks and eat or mutilate hooked line-fish (Rae 1960, 1969). In the Baltic Sea, seals, possibly greyand Baltic ringed seals take hooked linefish such as pike and garfish (Pilats 1989).

Fish Farming

Mong parts of the Scottish coast, grey and harbour seals are regularly seen around the cagesof salmon farms, bite at salmon through the cage walls and are evidently regarded as serious pestsat some salmon farms (Harwood 1991). This seal predation occurs all year around but mostly inwinter and particularly during bad storms when seals come into the lochs for shelter and are closerto the cages (Ross 1988). Predation also occurs more at night, possibly because salmon tend tocongregate at the cages bottom making them easier prey (Ross 1988).

Northridge (1988) and Ross (1988) report that many of salmon farms were estimated to sufferlosses due to seals of less than £1000 per year, but several other sites reported seal damage as amajor problem, with seal damage assessed at more than £10 000 per year and at one site, lossesto seals in 1985 were estimated to exceed £100 000. In 1987 it was estimated that harbour and greyseals were responsible for over 82% of damage to salmon held in cages in Scotland, which couldamount to £1.4 and £4.8 million annually, excluding indirect effects, most notably the increa.sedvulnerability to disease (Ross 1988, Anon 1988c). The scale of seal predation at these salmon farmswas found to be extremely variable, from no damage at some farms to losses of tens of thousandsof fish, valued at £280 000 per year, at others (Ross 1988).

4.2.2 Gear Darnal,Fe


In Britain, Scandinavia and the Mediterranean, grey, harbour, harp and monk seals andpossibly, ringed seals damage drift nets, stake and bag nets and wreck nets and eel traps (eg, Hardy1953, 1961, Lockie 1959, 1962, Rae 1960, Hickling 1964, Bonner 1969, 1972, Beverton 1985,Reijnders et al. 1993) but many fishermen think that this is minimal compared to damage fromother sources (Northridge 1988). With the progressive introduction of synthetic fibre nets in the1960's the number of damaged nets declined markedly and little damage was reported in the 1970's(Parrish and Shearer 1977, Harwood and Greenwood 1985).

There are often complaints by fishermen of seals going straight through drift nets, especiallyin the salmon fishery, in the northeast of England and Scotland, often in full view of fishermen whowait by the nets, attempting to keep seals at bay (Lister-Kaye 1979, Northridge 1988). In Scotlandseal damage to coastal nets ranged from less than 5% of the nets in some areas to more than 30%at others (Rae and Shearer 1965). In the Scottish stake and bag salmon net fisheries for salmon,seals occasionally enter these nets and may tear them while trying to get out (Northridge 1988).In northeast England the cost of repairing set nets as a result of grey seals amounted to between £6and £39 per fishing trip (Heap et al. 1986). Harbour seals damage nets in the small herring driftnet fishery off southeast England, normally going straight through the net (Northridge 1988).

In Denmark, eel traps are easily broken by harbour seals and no eels are subsequently caughtwhen the net is broken (Hansen 1987). Harbour seals used to cause damage to pound nets but achange to synthetic material has reduced this to a rare occurrence (Hansen 1987).

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In Norway, inshore net damage by harbour and grey seals along parts of the coast wasreported by 62% of fishermen (Oritsland and Bjorge 1981). In 1980, Norwegian fishermenestimated that damage by grey or harbour seals to fishing gear, mostly gill nets, buoyed salmon trapand bag nets for storage of sprat or cultured salmon, amounted to between N.Kr 170 and N.Kr 30000, averaging N.Kr 2 900, while the cost of damage as a result of harp seals was estimated atN.Kr 610 000 in 1979 and N.Kr 980 000 (Bjorge et al. 1981). It was estimated that 3000 - 4000nets were damaged annually by harp seals in the Varanger Fjord area of Norway was and may havecaused damages of up to $300 000 (Ulhang 1981). In the east Baltic, seals, possibly grey and ringedseals, damage nets used in the whitefish fishery (Pilats 1989).

In the Mediterranean, damage to gear, mostly to gill nets by monk seals has been reported(Ronald and Healy 1974, Shultze-Westrum 1976, Marchessaux and Duguy 1977, Berkes et al.1979, Boulva 1979, Berkes 1982, Panou et al. 1993). In Greece monk seals are reported to makecharacteristic holes 20-30 cm in trammel nets, with damages per trip estimated at 7.7% for offshoretrammel net trips 13.0% of inshore trammel net trips and 7.7% of gill net trips (Panou et al. 1993).


In Greece, monk seal damage was found on 1.3% of trips using bottom long-lines (Panou etal. 1993).

Fish Farming

On Scottish salmon farms, grey and harbour seals occasionally cause net damage but specificincidents can have substantial impacts (Ross 1988, Harwood 1991).



Grey and harbour seals disturb fishing at gill and pound nets in Britain and Scandinavia. InBritain, seals are reported to wait at the entrance to nets and divert fish from entering the net (Rae1960). Scottish fishermen claim that fish can smell when a seal has been in their nets and this candeter fish from entering the nets for several days (Rae 1960). Some support for this belief is givenby Alderdice et al. (1954) who found that the movements of Pacific salmon were influenced by theplacing an extract from seal skin into the water, but these effects are difficult to quantify. Harbourseals in Britain have even been reported to chew marker buoys, which can be a great nuisance(Northridge 1988). In Denmark, harbour seals are reported to frighten the fish away from the

entrance to pound nets and this is possibly the most detrimental effect on the industry but isimpossible to prove or cost (Hansen 1987).

Fish Farming

Grey and/or harbour seals disrupt salmon in fish farms in Scotland. Salmon farmers there

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believe that the presence of seals causes stress to salmon which results in reduced growth rates ofsalmon; wounded fish are highly susceptible to disease which can spread to the remainder of thestock. This is seen as a much greater threat to wiping out stocks than direct damage by predators.Stress from the mere of predators causes increases their vulnerability to disease, and the disruptionin fe,eding causes loss in growth (Ross 1988, Harwood 1991).


Seven of the 12 pinniped species found in this area (grey, Eastern Atlantic harbour, harp,Baltic ringed, Saimaa, hooded and Mediterranean monk seals) are incidentally or deliberately Id'ledduring all forms of fishing - passive and active net fishing, active and passive line fishing andduring fish farming.


In western Europe the seals involved in interactions are not always specified by species sogrey and harbour seals are combined here where distinguishing information was not given.

Grey and Eastern Atlantic Harbour Seals

Grey and/or harbour seals are taken in gill, wreck and trammel nets and fykes, pair trawls,midwater trawls, active line gear and anti-predator nets around fish farms in Britain and theNetherlands (eg, Reijnders and Lankester 1990). Northridge (1988) provides historical informationon the incidental deaths of grey and/or harbour seals, namely 3 seals in tangle nets, one prior tothe 1970's, and two in the 1980's; 2 seals in midwater trawl nets in the 1970's and several sealsin these nets during the 1980's; 3 seals in gill nets in the 1980's; 2 seals in a trammel net and oneseal in a wreck net in the 1980's (Northridge 1988). Northridge (1988) suggested that at least a"couple of hundred" harbour and grey seals may be taken annually and more than 100 seals of bothspecies may drown in anti-predator nets on Scottish salmon farms. Occasionally seals are drownedby taldng a hook from a line fishermen on the Scottish and English coasts (Rae 1969). In theNetherlands, there are regular reports of seals being caught in fyke nets and in one area about 10seals drown each year in these nets (ICES 1992a).

Grey Seals

Grey seals are caught during gill, bag, fly and tangle net and seine fishing in Britain, Franceand Scandinavia (eg, Rae 1968, Bonner 1979, Scialabba 1989, Helle 1979, Almkvist et al. 1980,Reijnders et al. 1993). In a small tangle net fishery in Scotland, catch rates appeared quite high,for example one fisherman took 36 grey seals in one season (Northridge 1988). Most seals foundin nets are young, and from tagging results it appears that a minimum of between 1 and 2% of sealpups drown in fishing gear (Northridge 1988). Off the Northumberland and Berwickshire coast ofBritain, Lockie (1959) reported 14 grey seals taken in salmon set nets between 1956 and 1958. InScotland, several grey seals have drowned in cod nets and a grey seal was reported drowned by

33

becoming caught on a fish hook (Rae 1960). In a sample of grey seals examined between January1967 to June 1971, 119 were from salmon nets and 13 from whitefish and herring nets (Rae 1973).Of 528 grey seals tagged that were found dead, 148 (28%) were found in nets but this is likely tobe an overestimate because drowned seals are more likely to be returned than those dying of naturalcauses (Harwood and Greenwood 1985). In a small area around Montrose, the number of grey sealsrecorded from 1961 to 1980 was 128 in salmon bag nets, 72 in salmon fly nets, 38 in cod nets andtwo in seines (NERC 1984).

Along a section of the coast of Norway, the minimum first year mortality rate of 8% afterweaning is largely attributed to incidental catches in fishing gear (Oritsland and Bjorge 1981).Between 1974 and 1985, it was estimated that approximately 20% of grey seal pups in the 13alticSea were ldlled in fishing gear annually (Sjoasen 1986). At the island of Hiiumaa in the East Balticconservative estimates of grey seals drowned in bag nets increased from 6 - 10 in the early 1980'sto 24 - 28 in the late 1980's (Pilats 1989). In the whole East Baltic, Pilats (1989) estimated that in1987 approximately 70 seals were taken incidentally in bag nets. The incidental catch variesannually, but the mortality in 1987 represented about 5% of the estimated population and affectedthe population negatively (Pilats 1989).

Eastern Atlantic Harbour Seal

Harbour seals drown in gill, bag and fly nets and fykes, trawls and anti-predator nets aroundfish farms in parts of Britain, Ireland, France and Denmark (eg, Rae 1968, McCarthy 1985,Scialabba 1989, Reijnders et al. 1993). In the Wash in England some tens of harbour seals maybe caught in midwater trawl sprats (Northridge 1988). In a sample of dead harbour seals examinedbetween January 1967 to June 1971, 9 were from salmon nets and 4 from whitefish nets (Rae1973). Lockie (1959) indicated that two harbour seals were taken in salmon set nets offNorthumberland and Berwickshire during 1957-58. Off Montrose between 1961 and 1980, NERC(1984) reported a total of 36 harbour seals were taken in salmon bag nets, 9 in salmon fly nets and2 harbour seals in cod net fisheries.

Several hundred harbour seals may drown in protective nets around salmon farms annually(Ross 1988). In the Netherlands during the periods 1971-1980 and 1982-1984, a minimum of 4 and12 young harbour seals, respectively, were reported to drown annually in mullet fykes and nets(Reijnders 1985). In Denmark, between 1889 and 1927 some 37 000 harbour seals were shot ordrowned in fishing tackle (Hansen 1987).

Harp Seals

Harp seals are taken in gill nets, trawls and longlines in Scandinavia. In northern Norwaythere have been some large catches of harp seals, particularly in the cod set net fisheries but alsoin longlines and trawls (Beverton 1985, Blix 1991, Haug et al. 1991). There is evidence that 10 I I I- 15 000 harp seals drowned annually in gill nets between 1978 and 1984 (Bjorge et al. 1981, ICES1990). An estimated 9000 or more harp seals were killed in gill nets for cod in 1980 (Ulltang 1981)and figures have ranged from 517 - 3311 animals annually in the early 1980's to 15 000 in 1984

34

and 4409 in 1986 (Malouf 1986, Oritsland 1990, Haug et al. 1991, ICES 1992b). In 1987, 56 222were reported caught, followed by more than 21 538 in 1988 (ICES 1990, Haug et al. 1990,Oritsland 1990, Haug et al. 1991, ICES 1992b), although it has been estimated that between 60 000to 100 000 animals died in 1987 (Wiig 1988). Thereafter numbers have decreased to those of theearly 1980's with only 1314 caught in 1989 (Haug et al. 1990) and only 368 seals in 1990(Oritsland 1990, Haug et al. 1991, ICES 1992b). The age composition of incidentally caught harpseals does not show any specific pattern in terms of age and sex caught (Haug et al. 1991).

These figures may generally be much lower than actual numbers of animals killed and shouldbe considered as a relative index (Haug et al. 1990). The high levels of incidental mortality of harpseals in Norwegian coastal waters from 1978 to 1988 have contributed to a significant decline inthe harp seal population that breeds in the 'White Sea (Ulltang 1989, ICES 1990).

Baltic Ringed Seals

Baltic ringed seals are taken in bag nets in Scandinavia. Several tens of thousands of Balticringed seals die each year through incidental catches in the Baltic Sea (Helle 1979, Almlcvist et al.1980, ICES 1992a, Reijnders et al. 1993). In the East Baltic at the Island of Hiiumaa conservativeestimates are of less than ten ringed seals drowned in bag nets in the 1980's (Pilats 1989).

Saimaa Seals

Saimaa seals are taken in fishing nets resulting in a high juvenile mortality which is one ofthe most important reasons that the population has decreased sharply from the early 1960's to theearly 1980's (Helle et al. 1981, Hvarinen and Sipilia 1983, 1984).

Hooded Seals

Hooded seals are taken off the northern coast of Norway in salmon driftnets and longlines(Northridge 1984).

Mediterranean Monk Seals

Mediterranean monk seals die in gill and trammel nets, trawls and longlines throughout thespecies range and although there are very few incidental deaths in fishing gears, this is an importantcomponent of seal mortality, probably one of the main causes of the population decline and hasbeen identified as one of the potential threats to the species (eg, Boulva 1979, Ronald and Duguy1979, Kenyon 1981, Ronald and Healy 1982, Reijnders et al. 1988, 1993, UNEP 1990, Panou etal. 1993).

Jacobs and Panou (1988) report that 8 out of 34 animals died from incidental mortality. Anon(1990d) report that 27 out of 40 died incidentally in fishing gear between 1980 and 1990 inMorocco. There is no evidence that any specific age or sex is particularly vulnerable (Anon 1990d).

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Monk seals have be,en caught on baited hooks in the Danube Delta (Schnapp et al. 1962), intuna nets at Cassis in France since the 1930's (Cheylan 1974, Sergeant et al. 1978), in trammel netsin the Bay of Tunis (Othman et al. 1971), infrequently in trammel nets in Italy although this wasmore common in the 1940's (Di Natale and Notarbartolo-di-Sciara 1990), occasionally in coastalgill nets in Greece (Northridge 1984), Mauritania (Scialabba 1989), Morocco (Maigret 1990) andAlgeria (Di Natale and Notarbartolo-di-Sciara 1990), in trawl nets near Spanish Morocco in the1970's (Soriguer 1977), in undefined gear on the coast of Spanish Sahara in 1913 -ttger 1951)and in the 1970's in Turkey (Berkes 1976). In the Ionian Sea, 8 monk seals are reported to havedrowned in fishing gear, of which 3 are known to have died in trammel nets, 2 in gill nets, and onewas taken on a longline (Anon 1988a). A single monk seal died in a trammel net off SantoriniIsland (Greece) in March of 1990 (Cebrian et al. 1990) and one died in a gill net off Moroccobetween 1980 and 1982 (Maigret 1990).


Grey and Harbour Seals

Northridge (1988) reports that probably 1000 seals of both species may be shot by Scottishsalmon farm operators.

Grey Seals

Grey seals in Scotland are deliberately killed by fishermen to prevent them from damagingtheir catch and gear, and specifically in Scotland, grey seals are shot by some fishermen if they areconsidered to be causing damage to the salmon in cages (Harwood and Greenwood 1985, Ross1988, Reijnders et al. 1993). In a sample of grey seals examined between January 1967 to June1971, 109 seals had been shot by fishermen (Rae 1973).

Eastem Atlantic Harbour Seals

Harbour seals are killed in Scotland and Denmark if they interfere with fishing or fishfarming. In Scotland, harbour seals are shot by some fishermen if they are considered to becausing damage to the salmon in cages (Ross 1988). In a sample of harbour seals examined betweenJanuary 1967 to June 1971, 65 seals had been shot by fishermen (Rae 1973). In Denmark, between1889 and 1927 some 37 000 harbour seals were shot or drowned in fishing tackle (Hansen 1987).

Baltic Ringed Seals

Although ringed seals are protected, Swedish fishermen can shoot these seals around theirnets, and lcill to less than a few hundred seals annually (Durant and Harwood 1986).

Mediterranean Monk Seals

Deliberate lcilling of monk seals by fishermen in different areas of the Mediterranean is

36

probably one of the main causes of the population decline and has been identified as one of thepotential threats to the monk seals (Boulva 1979, Ronald and Duguy 1979, Ronald and Healy 1982,UNEP 1990, Reijnders et al. 1988, 1993, Panou et al. 1993).

Deliberate lcilling is primarily a problem in the eastern Mediterranean (Anon 1990d) occurringin Greece (Ronald and Healey 1974), the Turlcish Mediterranean and southern Aegean seas (Berkes1976) and the northern Aegean, Marmara and Black Seas (Berkes 1976) but also further west inTunisia (Muller 1975) and Algeria (Bahri 1974, Boulva 1975, Bougazelli 1979). Deliberate killingby fishermen was largely responsible for the disappearance of monk seals from Corsica (Boulva1975). In Algeria fishermen consider it unlucky to kill seals but younger fishermen are lessinhibited from lcilling seals (Sergeant et al. 1978, Berkes 1982).

Specific reports of deliberate Icills are 21 out of 34 dead monk seals reported to Jacobs andPanou (1988), 19 monk seals shot in Turkey (Berkes et al. 1979), 16 shot and a further 10 killedusing axes, sticks or thrown rocks in the Baleares (Avella 1979) and 11 lcilled along the coast ofTunisia, Algeria and Morocco (Avella 1987). Fishermen at Rhodes are reported to have shot dead20 monk seals in 1985 in retaliation for damage to gear (Naturopa cited by Northridge 1991a).

4A Mitigation Measures

In general, change in gear design or fishing method seems to be the most effective means ofcontrolling seal damage (Northridge 1988). The effects of the introduction of stronger, synthetic,twines to the Scottish stake net fishery is one such example of reducing net damage inflicted byseals (Lister-Kaye 1979, Northridge 1988) although Northridge (1988) points out that there is noevidence that the amount of fish damaged decreased. In the Netherlands, it was suggested that sealcatches in mullet nets and fykes could be reduced through gear modifications and Dutch fishermenare required to put a wide mesh net over the opening of fyke nets (Reijnders 1985, ICES 1992a).Although many salmon farm operators use anti-predator nets of various types, Ross (1988) foundthat they worked with varying degrees of success and that there is unlikely to be a simple universalsolution, but rather specific solutions at individual sites or in particular fisheries need to be workedout which are dependent on, for example, water current and degree of fouling. Nets are often lesseffective in areas of strong tidal flow, as seals can learn to push the nets against the cages andcontinue biting fish.

Potter and Swain (1979) and Northridge (1988) note that it appears to be only a small numberof the seals that are responsible for predation from salmon nets. For this reason, deterring or killingthose individuals which have learnt to depredate is thought to be more effective than general culling(Anon 1975c). Shooting and poison were both used against seals talcing salmon and damaging netsin Scotland, but neither approach was effective because shooting a moving target is difficult andthere are the risks and suffering involved in using poisons such as strychnine (Anon 1975c, Lister-Kaye 1979). Further seals become wary and stay below the surface (Thompson et al. 1984).

The use of acoustic devices to scare seals have been investigated in the Britain (Anon 1975c,

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Anderson and Hawlcins 1978, Ross 1988) but they proved ineffective in scaring seals (Andersonand Hawkins 1978). In Denmark various deterrents have been tested such as gas canons, fire effectsnear the tackle, shooting and chasing the seals near the tackle but the seals quickly s meaccustomed to the disturbance (Hansen 1987).

5. NORTHWEST PACIFIC OCEAN

This area includes Japan and the east coast of Asia (FAO area 61 and part of 18 and 71). Inthis area there is one sea lion species, one fur seal species, seven "true" seal species/subspecies anda walrus subspecies. Steller's sea lions are found from northern Japan along the east Russian coastand have a population in this area of 13500 - 13800 which is decreasing (Reijnders et al. 1993).They are listed as "Vulnerable" in the IUCN Red list 1993.

Northern fur seals are found from northern Japan along the Russian east coast with apopulation size of 335 000 - 350 000 in the area (Reijnders et al. 1993). The Western Pacificharbour seal is found along the northern Japan and the Russian east coast and numbers 3 950 in thisarea. This species has declined markedly as a result of deliberate and incidental mortality duringfishing (Wada et al. 1991, Hayama 1988). Larga seals are found along the east Russian coast andnorthern Japan and have a population size of over 130 000 in this area (Popov 1982). The effectof incidental and deliberate mortalities still to be assessed (Reijnders et al. 1993). Arctic ringedseals occur along the northern and northeastern coast of Russia with a population that is a part ofthe Bering Sea population of 70 000 - 80 000 animals (Popov 1982). Okhotsk ringed seals occuralong the east Russian coast and Japan and have a population of 800 000 - 1000 000 (Reijnders etal. 1993). The Baikal seal is found in the Baikal Sea and has a population of about 60 000 - 70 000(Pastukhov 1990). Incidental catches of young seals are a possible threat to the population(Reijnders et al. 1993). Ribbon seals are found along the east Russian coast and northern Japan witha population over 133 000 (Popov 1982). The Pacific bearded seal is found along the northeast andeast Russian coast and northern Japan and has a population in this area of between 200 000 and 450000 animals (Popov 1982).

The Pacific walrus is found along the Russian east coast and is a part of the total Pacificpopulation of 230 000 (Gilbert 1989) with an additional 4000 - 5000 animals found in the LaptevSea (Fay et al. 1990).


Six of the 10 pinnipeds found in this area (Steller's sea lions, northern fur seals, WesternPacific harbour seals, Larga seals, Okhotsk ringed seals and Pacific bearded seals) are involved ininteractions with passive net fishing.

5.1.1 Depredation

Passive Net and Trap Netting

Steller's sea lions, harbour seals Larga seals, northern fur seals, ringed seals and beardedseals depredate from gill nets trap in Japan and Russia In salmon trap nets, on Hokkaido Island,harbour seals, Larga seals, bearded seals, ringed seals and northern fur seals (in order of abundancein terms of those found dead in traps) cause salmon damage (Wada et al. 1986, 1991). Seals wereestimated to damage 5.1% (1982) and 1.8% (1983, when there was an early closure of the fishingseason) of salmon caught, most attributable to harbour seals (4.7% in 1982 and 1.7% in 1983)(Wada et al. 1991). Along the Hokkaido coast, particularly along the Rebun and Rishiri Islands andthe Shalcotan Peninsula, Steller's sea lions also take fish from bottom gill nets (Yamanalca et al.1986). Masuda (1986) estimates that the economic losses from seals feeding on salmon and causingsalmon impairment amounted to the equivalent of 2 to 4 persons share in the fishery co-operativesystem in southeastern Hoklcaido.

On Daikoku Island damage to salmon from trap nets from examination of wounded salmon(excluding severely damaged salmon je, no head) was 2.1% in 1983 and 3.2% in 1984, of the catch(Niizuma 1986). Cape Erimo in Japan, seals caused damage amounting to 1.4, 1.7 and 1.3% ofthe catches from three nets and the value of damaged salmon was 70-80% of normal price maldngthe losses equal to 0.3-0.5% of the income from these traps (Tanahashi and Itoo 1986). This areais the largest breeding area of harbour seals but there was no pattern of damage caused at the trapsclosest to the bre,eding ground. There was an inverse relationship between the size of the catch andthe percentage of salmon that was damaged (Tanahashi and Itoo 1986). Tanahashi and Itoo (1986)believe most predation takes place at night. In the Kamchatka region Larga seals and Steller's sealions damage caught fish, decreasing the quality of the fish (Burkanov 1990, Reijnders et al 1993).

5.1.2 Gear Damage


In Japan, along the Hokkaido coast, particularly along the Rebun and Rishiri Islands and theShakotan Peninsula, Steller's sea lions damage bottom gill nets as they take fish from the nets(Yamanaka et al. 1986).



Steller's sea lions disperse shoals of fish from bottom gill nets on the Holdcaido coast,particularly along the Rebun and Rishiri Islands and Shakotan Peninsula (Yamanaka et al. 1986).In Russia, in the Kamchatka region Larga seals and Steller's sea lions sometimes prevent fish fromentering traps (Burkanov 1990).

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Seven of the 10 pinniped species and subspecies found in this area (Steller's sea lions,northern fur seals, Western Pacific harbour seals, Larga seals, Okhotsk ringed seals, ribbon sealsand Pacific bearded seals) je, all except the freshwater Baikal seal and the Pacific walrus, are ldlledincidentally or deliberately during passive net and trap fishing and active net fishing.


Steller's Sea Lions

Steller's sea lions are taken during gill net and trawl fishing offshore from Russia and Japan.Yablokov (1981) reported that Soviet trawlers in the North Pacific may take several hundredSteller's sea lions annually while Burkanov (1990) noted that it is lcnown that they are caught bytrawlers in the Kamchatka region but no quantitative data are available.

Small catches of Steller's sea lions were reported to be caught during Japanese salmon driftnetresearch cruises - only a single seal in the period 1979 to 1987 (Ito 1986, FAJ 1986, 1987, 1988,Anon 1988b, Northridge 1991b).

Northem Fur Seals

Northern fur seals are taken in gill nets, traps and trawls in the North Pacific (eg, Fowler1982, Anon 1988b). It is estimated that Japanese salmon and squid fisheries take less than 200northern fur seals annually (NMFS 1992). In the Japanese mothership drift net salmon fishery,Fukuhara (1974) reported that approximately 3150 - 3750 fur seals were taken annually but it is notlcnown what proportion are released alive (Mate 1980). Lander (1979) and Lander and Kajimura(1982) estimated that the annual accidental catch may have been closer to 7000 because fur sealsmay have been used as food by the fishermen. Over 700 northern fur seals were estimated to havebeen killed in 1978 in this fishery (IUCN 1981, NMFS 1981). O'Hara et al. (1986) estimated that400 - 1000 animals were taken annually. Jones (1980, 1981, 1982) estimated that in the early1980's only 100 to 1000 fur seals were taken incidentally while reported incidental deaths in thisfishery were limited to 5 northern fur seals during 1985 to 1988 (Northridge 1991b).

Japanese research salmon cruises report catches of 74 northern fur seals between 1979 and1984, 3 in 1985, 7 in 1986 and 3 in 1987 (Ito 1986, FAJ 1986, 1987, 1988, Northridge 1991b).During Japanese squid driftnetting various figures have been reported. A total of 14 northern furseals were incidentally killed during 30 sets on a Japanese driftnet vessel in 1986 (Tasunoda 1989,NMFS 1992). During 1986/87, US observers noted that 24 northern fur seals died in squid driftnets (Jones 1988). In 1988 during 464 operations of squid driftnetting, 43 northern fur seals died(FM 1989) while in the same year, during 22 sets from a Korean vessel 2 northern fur seals werecaught but were released alive (Gooder 1989). In 1989 during 1402 sets, 52 northern fur seals died(Gjernes et al. 1990, NMFS 1992) while (Northridge 1991a) gives a total of approximately 2 700northern fur seal incidental deaths; (Larntz and Garrott 1991) gives 1592 for seals of dead or of

39

40

unlcnown status of (236 - 2922, 95% confidence intervals) or 1592 (1000 - 2350, 95% confidenceintervals) (Yatsu and Hayase 1991). In 1990, Baba et al. (1991) give 1033 females (up to 1300,95% confidence intervals) for the incidental take (dead or of unlcnown status). Yatsu and Hayase(1991) give 2066 (1600 - 2600, 95% confidence intervals) as taken in total. The incidental catchin the Japanese squid fishery has been mainly of 1/2 year-old animals and catch rates have rangedfrom 0.25 (1988) and 0.15 (1989) to 0.23 (1990) per 1000 tans (Anon 1991b). Recent preliminaryestimates are of more than 2100 fur seals dying annually due to entanglement in squid driftnets(MMC 1991).

Research drift nets for squid in the northwest Pacific, which generally have larger mesh sizethan commercial nets, appear to catch more pinnipeds than commercial nets (Northridge 1991b).In 1988, using equal lengths of research and commercial nets, Yatsu (1989) reported that during33 squid netting operations, 4 northern fur seals were ta.ken, all in research nets. Other figures fornorthern fur se,a1 incidental deaths during research cruises using both research and commercial nets,are 4 during 42 sets in 1986 (Murata 1987), 4 during 45 sets in 1987 (Murata et al. 1988), 3 during73 sets in 1988 (Murata et al. 1989) and 4 during 29 sets in 1989 (Kawasaki et al. 1989).

In salmon traps on Holdcaido Island, one northern fur seal was reported to have drowned in1982 and 1983 (Wada et al. 1986, 1991). During a six-day observation period in 1984, a singlenorthern fur seal died in a salmon trap net on Daikoku Island (Niizuma 1986). In the Kamchatka,region northern fur seals are caught incidentally in salmon drift nets and walleye pollock and codtrawls (Burkanov 1990). Catch rates in the Taiwanese large mesh fishery for tuna and billfish arepreliminary put at 0.14 of dead and unknown animals per 1000 tans (Anon 1991b).

Western Pacific Harbour Seals

Harbour seals are taken in gill nets and traps in Japan. Incidental catches of harbour seals arelow except in the waters around Hokkaido Island where there is greater use of large salmon trapnetsand smaller gill nets and where incidental deaths exce,ed the number of pups born (Reijnders et al.1993). Naito (1976) indicated that some harbour seals are incidentally taken in salmon set nets offthe coast of Japan's Islands. Kuzin et al. (1974) reported 1483 harbour seals dying in nets aroundthe Kuril Islands in 1970 and 557 dying in nets in 1971 around the Habomai Islands. During 1982and 1983 on Holcicaido Island 163 harbour seals drowned in salmon trap nets annually with almostall being found at one particular site, Habomai Fishermen's Cooperative Association and aparticular trap (Trap 27), close to the Nosappu Cape; this is about one half of the population alongthe southeastern coast of Holdcaido Island, or more than 8% of the total population (VVada et al.1986, 1991). After discontinuation of salmon trap nets at this and a neighbouring site, the numberof dead seals increased at other traps, suggesting that the seals moved elsewhere (Wada et al.1991). Most of the seals caught were pups (27%) and subadults (69%) (Wada et al. 1991). OnDaikoku Island during a six-day period 2 harbour seal pups were captured in 1984 in salmon trapnets (Niizuma 1986). Wada et al. (1991) suggest that these seals had learned the structure of thesalmon net and could escape without drowning. Itoo and Shikunobe (1986) found that it wasdifficult to link the number of dead seals directly with population changes at haul-out sites.

Larga Seals

Larga seals are taken in gill nets and traps in Japan and Russia. Naito (1976) reported at least27 incidental mortalities of Larga seals in fishing nets in the coastal waters of Japan in 1969-1971.During 1982 and 1983 on Hokkaido Island, 97 Larga seals were caught incidentally and died in trapnets set, most being found at one particular site, Habomai Fishermen's Cooperative Associationand in a particular trap (Trap 27), close to the Nosappu Cape (VVada et al. 1986, 1991). In 1984during a six-day period, 10 Larga seals, mostly pups, were caught in salmon trap nets on DaikokuIsland (Niizuma 1986). Accidental mortality of Larga seals occurs in the crab trap-net fisheries inKamchatica (Burkanov 1990) and Barlow et al. (in press) reports a Larga seal entangled in crabfishing gear.

Okhotsk Ringed Seals

A total of 9 ringed seals were reported to have been incidentally caught in salmon set nets andother fishing nets in Japan between 1969 and 1975 (Naito 1976). During 1982 and 1983 onHoldcaido Island a single ringed seal was caught incidentally and died in a salmon trap net (Wadaet al. 1986, 1991). Few ringed seals are caught in Japanese salmon drift-net research cruises - onlya single seal in the period 1979 to 1987 (Ito 1986, FAJ 1986, 1987, 1988, Northridge 1991b).

Ribbon Seals

A few ribbon seals are caught incidentally by gill net and trap fishing in Japan (eg, Reijnderset al. 1993). On Hokkaido Island during 1982 and 1983 10 ribbon seals died incidentally in trapnets (Wada et al. 1986, 1991). In the coastal waters of the Japanese islands, Naito (1976)documented the incidental catch of two ribbon seals in salmon set nets during 1970 to 1971. Duringa six-day period in 1984, 14 seals lcilled in salmon trap nets off Daikoku Island, one was an adultmale (Niizuma 1986). Naito (1976) reported the incidental catch of 3 ribbon seals by offshore gillnets in 1969 and a single ribbon seal was reported drowned in Japanese salmon gill nets in 1981in the west Bering Sea (Stewart and Everett 1983).

Pacific Bearded Seals

Bearded seals are taken in traps in Japan. Naito (1976) reported a take of at least six animalsfrom 1968 to 1970 in the coastal waters of Japan. On Holckaido Island during 1982 and 1983 asingle bearded seal died in a salmon trap net (Wada et al. 1986, 1991).


Steller's Sea Lions

Steller's sea lions are shot in the Bering Sea by salmon fishermen in an attempt to preventdamage to their catches in nets (Burlcanov 1990).

41

Larga Seals

Larga seals are shot by salmon fishermen to prevent damage to their catches in nets(Burkanov 1990, Reijnders et al. 1993).


To investigate means of alleviating damage on bottom set nets in Holckaido baited bag netsof different strengths were tested against attack from Steller's sea lions (Sasalcawa 1989). It wasshown that bags of more than 75 yarns were safe from damage by sea lions and knotted webbingis better in preventing the spread of broken areas (Sasalcawa 1989). An automatic explosionsimulator to keep sea lions away from nets was tested in Hokkaido and during 13 hauls of the netgood catches were made without damage from sea lions (Sasakawa 1989).

6. SOUTH PACIF1C/ATLANTIC OCEANS


This area includes South America south of the equator and the Galapagos Islands (FAO area87 and most of 41 and part of 77). In this area there are two species/subspecies of sea lion, threespecies of fur seal and a single "true" seal species. Galapagos sea lions are found on the GalapagosIslands and there is an estimated population of 30 000 individuals (Trillmich 1979). South Americansea lions are found along the Peruvian, Chilean and Argentinean coasts and at the Falkland Islandsand have a population size of 155 000 (calculated from Reijnders et al. 1993) that has declined.This may be due to deliberate killing by fishermen (Reijnders et al. 1993).

Galapagos fur seals are found only on the Galapagos Islands and have a population of less than40 000 (Trillmich and Ono 1991). Juan Fernandez fur seals are found on the Juan Fernandez andDesventuradas Islands of Chile, and have a population size of 18 295 which is increasing (J.Francis, pers. comm.). South American fur seals are found along the coast of southern Peru andthroughout Chile, the coast of Uruguay and the Falkland Islands with a population size of 235 000 -285 000 (P. Majluf, M. Lima and A. Ponce de Leon, pers. comm.). Southern elephant seals are

found in Argentina and the Falkland Islands; these animals are a proportion of a total populationof 700 000 - 800 000 animals (calculated from Reijnders et al. 1993).

Only one of the 6 pinnipeds found in this area (South American sea lions) are reported tointerfere with passive net and line fishing, active line fishing and fish farms.

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6.2.1 Depredation


South American sea lions are known to depredate fish caught in gill nets in a number of areasalong the west and east coasts of South America, often only consuming the visceral (eg, yaz-Ferreira 1979, 1982).

In the Necochea and Clameco shark fisheries, South American sea lions damage catches,generally biting the belly of the entangled fish and taldng the liver (Corcuera et al. 1990, Crespoand Corcuera 1990, Crespo 1992). An example is given by Crespo and Corcuera (1990) who reportthat during a survey trip in 1989 a single male South American sea lion damaged almost 60% ofthe catch.

South American sea lions, mainly adult males, remove whole fish from sciaenid and ratfishnets in southern Chile and also take the belly portion of netted fish, most frequently attacldngsciaenids (Oporto et al. 1991). Depredation occurs mainly in winter and spring and is done byindividuals or groups of 3-6 animals per net, although one individual is capable of destroying anentire day's catch (Oporto et al. 1991). At a single one of the 35 localities of artisanal fisheries forsciaenids at Queule in southern Chile, depredation by sea lions amounted to about 140 tons, at acost of nearly $120 000 per year or 35% of the value of gill net fisheries (Oporto et al. 1991).


South American sea lions are known to depredate fish caught on passive lines (longline), oftenconsuming the visceral parts only (Vaz-Ferreira 1979, 1982).

Fish Farming

South American sea lions depredate from fish farms in Chile. They attack raft-pens on salmonfarms taking or damaging fish through the net, usually taking the belly portion (Oporto et al.1991). This is usually done by 3 or 4 individuals. Losses vary according to the size of the salmonfarms and the proximity to sea lion rookeries (Oporto et al. 1991). Losses per salmon farm wereestimated at between $7 000 and $40 000, or 0.5-2.2% of total net salmon production (Oporto etal. 1991).

6.2.2 Gear Damage


South American sea lions can cause serious damage to both shark nets and sciaenid and ratfishall nets on the west and east coasts of South America (eg, Vaz Ferreira 1982, Crespo 1992).

43

44

Fishermen in southern Chile claim that at least 1 to 2 days a week are needed to repair the netsduring which time they could be fishing (Oporto et al. 1991).

Active Line Fishing

South American sea lions can damage squid jigs in trying to remove squid from the jigs onthe South American east coast (Crespo et al. 1992).

Fish Farming

South American sea lions, particularly adult males, attack raft-pens of the salmon farms,ripping open the nets and allowing salmon to escape (Oporto and Leal 1990, Oporto et al. 1991).


Fish farming

South American sea lions disturb fish in fish cages in Chile. When South American sea lionsare around raft-pens on salmon farms, their presence causes stress to the fish malcing them moresusceptible to disease or causing them to crowd, resulting in deteriorating of body condition andmaking them unmarketable or diminishing their value (Bonner 1982, Oporto and Leal 1990).


6.3.1 Species Affected

Four of the 6 pinniped species found in this area, (South American sea lions, Galapagos, JuanFernandez and South American fur seals) are Idlled incidentally or deliberately during all types offishing - passive and active netting and line fishing and fish farming. In addition, 3 of the 5pinniped species found in the Southern Ocean may also be deliberately killed by fishermen for baitor otherwise.


South American Sea Lions

South American sea lions are known to be caught shark gill nets but rarely in trawls inUruguay and Argentina (Pinedo 1984, Scialabba 1989, Crespo and Corcuera 1990).

South American Fur Seals

South American fur seals are taken incidentally in gill nets, rarely in trawls and also insalmon farm nets and anti-predator nets in Uruguay, Argentina, the Falkland Islands and Peru (eg,

45

Oporto 1990, Reyes and Oporto 1990). In the Falkland Islands, although observer reports fromtrawlers indicate that South American fur seals are quite often seen near fishing operations, in 4years there is only 1 record of a fur seal drowning (Scialabba 1989).

Galapagos Fur Seals

Galapagos fur seals have died in gill nets but the problem seems to have been resolved(Reijnders et al. 1993).


South American Sea Lions

South American sea lions are Idlled by fishermen, probably in all are,as in which fishing(including gill nets, trawls, long-lines, trolling and fish farming) occurs and are may beconsiderable mortality (eg, Vaz-Ferreira 1979, 1982, Pinedo 1984). They are also Idlled by kingcrab fishermen for bait in southern Chile and Argentina (Cardenas et al. 1987, Lesrauweat 1990,Oporto 1990, Torres et al. 1990).

There is periodic indiscriminate lcilling of sea lions using a variety of methods but this isdifficult to determine although local populations are reported to have been considerably reduced(Oporto et al. 1991). Oporto et al. (1991) also provide an example of permits issued that exceedthe local population sizes. Torres et al. (1990) report that South American sea lions that areconsidered "harmful" to fishing activities because they take netted fish may be killed without apermit in Chile.

Trawl, gill net and squid jigging fishermen and salmon farmers shoot South American sealions or kill them in other ways (including use of dynamite) in southern Brazil, Uruguay, Argentina,Chile and Peru (Pined° 1986, Crespo 1992, Crespo et al. 1992, Reijnders et al. 1993). In Brazilmost of the animals found dead on the beaches show signs of mutilation through scars or woundsmade with firearms, sticks, ropes or nets (Pinedo 1986, Rosas 1989). In Chile sciaenid and ratfishnet fishermen frequently kill South American sea lions and at Queule have utilised the military tocarry out culls on all ages at certain rookeries (Oporto et al. 1991). In southern Chile, an increasein salmon farming has resulted in considerable legal and illegal hunting of South American sea lions(Woodley and Lavigne 1991). Since 1988 the talcing of pinnipeds for bait has decreased as sea lionshave become more scarce and wary of the fishermen, the Argentinean side of the Beagle Channeland near Cape Horn, deliberate killing for bait has decreased (Crespo and Corcuera 1990, Oportoet al. 1991, Crespo 1992).

Juan Fernandez Fur Seal

There may have been some illegal catch of Juan Fernandez fur seals for lobster bait (Hubbsand Norris 1971, Reijnders et al. 1993).

South American Fur Seals

In the Beagle Channel South American fur seals are used fcir king crab bait (Crespo andCorcuera 1990, Oporto et al. 1991, Crespo 1992, Reijnders et al. 1993) but although the practicecontinues in southern Chile, it seems to have decreased on the Argentinean side of the Channel(Crespo and Corcuera 1990, Crespo 1992).

Antarctic Fur Seals

Leopard seals may be captured for use as bait in the ldng crab fishery (Oporto et al. 1991).

Weddell Seals

In southern Chile in 1990 fishermen are known to have killed a Weddell seal at Queule,possibly only because it was in the area and not because it was interfering with fishing (Oporto etal. 1991).

Leopard Seals

Leopard seals may be captured for use as bait in the king crab fishery (Oporto et al. 1991)and fishermen are known to have killed a female leopard seal at Corral Bay in southern Chile,possibly only because it was in the area and not because it was interfering with fishing (Oporto andBrieva 1986).


Various methods have been used to decrease interactions in Chile, including armed guardswhich shoot at seals, anti-sea lion nets on fish farms, acoustic harassment devices, buckets withfire, fish filled with poisoned bait or sharp objects such as glass, spearing seals with iron toolsleaving them to rot in the hopes that other sea lions will avoid the area, and making captured sealions ingest huge amounts of carbide so that the resultant gas in their stomachs makes themincapable of diving and they are then lcilled with sticks and shotguns (Oporto and Leal 1990, Oportoet al. 1991). Anti-sea lion nets which keep sea lions away from the raft-pens are one of the mostsuccessful methods adopted, but they cause entanglement of sea lions in these nets (Oporto and Leal1990, Oporto et al. 1991). Approximately 12.5% of salmon farms use, or have used, acousticharassment devices but sea lions become habituated to them (Oporto and Leal 1990, Oporto et al.1991) and the frequencies used may be incorrect for South American sea lions or individuals havedifferent sound or intensity tolerances (Geiger 1985). The use of fish filled with poisoned bait orsharp objects such as glass is apparently not effective because sea lions avoid damaged fish (Oportoet al. 1991)

46

47

7. SOUTH ATLANTIC/ I i OCEANS


This area includes the coast of Africa south of the equator, (FAO area 47 and part of areas34 and 51). Only one subspecies of pinniped is resident in this area. South African fur seals arefound on the Namibian coast and the west and south coast of South Africa with a population of upto 2 million animals, that is increasing (Butterworth et al. 1991).

South African fur seals interact with passive and active forms of net and line fishing on thewest and south coast of southern Africa and overall operational interactions are estimated to costthe fishing industry in South Africa alone some R2 - 5 million per year (0.3 - 0.7% of the valueof the fishery) (Wickens 1994b).


7.2.1 Depredation


Seals take fish from inshore gill nets and lobster associated with the trap and hoopnet fisheryin South Africa (eg, Wickens 1989, 1991, Cochrane and Wickens 1990). In 1989 minimal gill netfishery losses were estimated to be about 21 t or R39 000 (Wickens et al. 1992). Based on anobserver programme in 1993, losses caused by seals were calculated to be a few thousand Rand peryear, with losses occurring particularly to St Joseph shark nets (1.6% of netted fish) rather thanfrom mullet nets (0.2% of netted fish) (VVickens 1993, 1994b, 1994e, submitted(1994c)). Seals areunlikely to take lobster that form part of the catch from lobster traps and hoopnets, but they do takeundersize lobster that are returned to the sea (Wickens et al. 1992, Wickens 1993, 1994b, d, e,sub mitted (b)) .

Active Net Fishing

South African fur seals take fish from purse-seine and trawl (inshore and offshore, bottomand midwater) nets but neither is considered to be a major problem because much of this fish arediscards by the vessels (eg, Rand 1959, Shaughnessy et al. 1981, Shaughnessy 1985, Anon 1987,David 1987, Wickens 1989, 1991, 1994a, Cochrane and Wickens 1990, Reijnders et al. 1993). Theamount of fish taken from purse-seine nets is not large, possibly 759 t/year (Wickens et al. 1992).

The amount of fish taken from offshore demersal nets is not large, possibly 796 t,/year(Wickens et al. 1992). The distribution of seals has been shown to be significantly influenced bycommercial offshore trawling because seals feed on fish scale available as a result of trawlingactivities (Ryan and Moloney 1988). David (1987) showed that, although there were claims that thetrawling industry in South Africa was supporting an artificially high seals population through seals

48

scavenging, this could not be demonstrated on the basis of seal consumption rates and numbers ofseals attending trawler nets.

Predation by South African fur seals from inshore trawl nets results in the loss of fish;approximately 0.7% of sole are damaged and 11.7% of Idngklip, but sole are easily removed wholeand therefore are not recorded in the catch so this is an underestimate (Wickens 1993, 1994b, e,Wickens and Sims in press). In total this amounts to some R70 000/yr (0.3% of the value of thefishery) in losses of sole and ldngklip (Wickens 1993, 1994b, e, Wickens and Sims in press).


During demersal long-lining, a method not currently used, seals were lcnown to take fish,often only talcing the belly portion (eg, Anon 1972, David 1987, Wickens 1989, Cochrane andWickens 1990, Wickens 1991, 1993, 1994b). Losses were large, averaging 11.6% over the five-year period from 1985 to 1989, although the depredation rate did decrease from 19.4% in 1986to 5.3% in 1989. The cost was R1394/yr in 1992 (Wickens et al. 1992).

Active Line Fishing

Seals taldng either whole fish and damaging fish, from handlines is a problem, particularlyduring snoek fishing and seals can be a minor problem during squid jigging, tuna long-lining andsport fishing (eg, Nepgen 1970, Shaughnessy et al. 1981, Shaughnessy 1982, 1985, Wickens 1989,Anon 1990a, Cochrane and Wickens 1990, Hanks 1990, Wickens 1991, 1994f). A questionnairesurvey showed that fishermen considered seals frequently to cause loss of fish and tacIde becausethey are nearly always present (Wickens 1993, 1994b, c).

Meyer et al. (1992) estimated that 8.3% (1988), 2.8% (1989), 0.7% (190) and 3.6% (1991)of handline-caught fish were lost to seals. The amount lost was 2.3% for all species caught and forthe two predominant fish species, 3.0% for snoek and 1.5% for hottentot, the difference in lossesbetween the two species was significant (Meyer et al. 1992). They estimated that R230 000 (0.2%of the value of the fishery) was lost through depredation by seals in 1989. Wickens et al. (1992)put the figure at R911 000/yr in 1989 for depredation from handlines by seals.

Meyer et al. (1992) showed that 67% of trips returned without loss although Wickens (1993,1994b) showed the reverse, that during snoek fishing in the peak period, on two-thirds of trips somelosses occurred (Wickens 1993, 1994b, c, submitted(a)). Based on an observer programme ofsnoek fishing in South Africa during 1992, losses caused by seals amounted to 5.4% of all fishcaught; a further 1.5% were damaged with cost estimated between R435 000 to R871 000 (3.1 to6.2% of the value of the fishery). This excludes the losses in vessel running time, bait costs etc.(Meyer et al. 1992, Wickens 1993, 1994b, c, e, submitted(a)). During other forms of line-fishing,losses were estimated to be between R20 000 (if only hottentot were considered) and R375 000/yr(if all other handline caught fish were assumed to be lost at this rate) (0.1-1.5% of the value of thefishery), excluding vessel running costs.

7.2.2 Gear Damage


South African fur seals tear nets in the inshore drift netting fishery but the damage is difficultto quantify and they may also damage or remove bait bags attached to lobster hoopnets (eg, Rand1959, Wickens 1989, Cochrane and Wickens 1990, Wickens et al. 1992, Wickens 1994e,submitted(c)). The minimal loss of bait bags from lobster hoopnets was estimated to cost, R2 517in 1992 (Wickens 1993, 1994b, d, submitted(b)).

Active Net Fishing

Seals are reported to damage purse-seine nets and trawl nets but this is of negligible costalthough some trawler propellers can be damaged (eg, Shaughnessy 1979, Wickens 1994a). In thedemersal offshore trawling fishery, seals are known to become caught in propeller nozzles, causingand great cost to the companies involved (Anon 1987, Wickens 1989, Cochrane and Wickens 1990,Wickens 1991, 1993, 1994b, e, Wickens et al. 1992, Wickens and Sims in press). The cost ofdamage to propeller blades was estimated at R308 000 in 1989 and in one case a company decidedto redesign the deck layout at a cost of one million Rand per vessel for two vessels (Wickens et al.1992).


Seals may cause losses of gear during tuna long-lining (Cochrane and Wickens 1990, Wickens1989, Wickens et al. 1992, Wickens 1993, 1994b).

Active Line Fishing

Seals result in loss of line fishing tackle during handline fishing, particularly during fishingfor snoek but also during tuna sport fishing and squid jigging (eg,.Shaughnessy 1985, Wickens1989, 1991, 1994 e, f, Cochrane and Wickens 1990, Wickens et al. 1992). During handline fishingMeyer et al. (1992) estimated that R42 000 (0.035% of the value of the fishery) was lost to sealsin 1989. While fishing for snoek an estimated 2.3% of tackle is lost to seals, amounting to betweenR26 000 and R109 000 or equivalent to 0.2 - 0.8% of the value of the fishery (Wickens et al. 1993,1994b, c, submitted(a)). During other forms of line fishing the loss of tackle to seals is estimatedat R4000/yr or 0.02% of the value of the fishery (Meyer et al. 1992, Wickens 1993, 1994b, c,submitted(a)).



Seals are believed to disturb lobster from hoopnets (Rand 1959, Cochrane and Wickens 1990,Wickens et al. 1992, Wickens 1989, 1993, 1994b, d, e).

49

Active Net Fishing

Seals frighten fish from purse-seine nets and disrupt fishing if they are caught in the fishpump or come aboard purse-seiners or trawls when they can then be difficult to remove and mayinjure crew members (eg, Anon 1972, Shaughnessy 1979, 1981, 1982, 1985, David 1987, Wickens1989, 1991, 1994 e, f, Cochrane and Wickens 1990, Reijnders et al. 1993, Wickens and Sims inpress). Observations show that for 5% of purse-seine hauls seals cause losses of fish from the netat a estimated cost of R1.4 million (Wickens 1993, 1994a, b). Although Wickens et al. (1992)calculated that loss of a fish shoal resulting from seals occurred 24 times per year for the wholepurse-seine fleet. Wickens (1993, 1994a, b), using direct observations, estimated that this happens8 times per vessel per year for the 87 active vessels.

Shaughnessy et al. (1981) report over a hundred seals and up to 500 seals around purse-seinersin Namibia, Thomas and Schulein (1988) indicate that commonly over 50 and often over 300 sealsmay be seen in the same situation but (Wickens et al. 1993, 1994a, b) saw an averaging 9 sealswith no more than 90 seals during observations in South Africa,

Active Line Fishing

Seals may cause linefish shoals (eg, snoek or squid) to disperse and may feed on the chumand disrupt tuna (eg, Rand 1959, Wickens 1989, 1993, 1994a, b, c, Cochrane and Wickens 1990,Meyer et al. 1992, Wickens et al. 1992). During observations, (3.6% of days observed) a sidboatonce moved because of seal numbers during hottentot fishing and on 4 occasions (2.4% of daysobserved) seals were thought to cause snoek to sound (Meyer et al. 1992).



South African fur seals are caught incidentally or deliberately Idlled during all forms ofpassive and active net and line fishing.

South African Fur Seals

South African fur seals drown gill nets, trawls and purse-seines (eg, Shaughnessy 1979, 1982,Shaughnessy et al. 1981, Wickens 1994e, f). Shaughnessy and Payne (1979) calculated that 0.057seals drowned per trawl on the west coast and between 0.005 and 0.032 seals per trawl drownedon the south coast, Wickens et al. (1992), based on their figures for the west coast, calculated thatthis amounted to 1089 seals per year in this area. Based on observations during 1992 and 1993,figures indicate that 438 - 1610 for seals drown annually in offshore demersal trawl nets, 1079 ininshore demersal trawl nets, 1034 in midwater trawl nets, 174 in purse-seine nets and 14 in inshoredrift nets (Wickens 1993, 1994a, b, submitted(c), Wickens and Sims in press).

50


South African Fur Seals

South African fur seals are shot by the fishermen during all forms of passive and active netand line fishing and they may be deliberately killed if they pose a threat to the safety of thefishermen, eg, if they come aboard a fishing vessel (eg, Shaughnessy 1979, Shaughnessy and Payne1979, Wickens et al. 1992, Wickens 1994c, e, f). Shaughnessy (1985) reported that aerial surveysof the coastline in Namibia, which showed dead seals on the beaches, indicated that there is ahigher mortality rate of seals during the purse-seine fishing season than at other times, indicatingthat perhaps seals are killed by fishermen during this time.

Shaughnessy and Payne (1979) calculated that when from seals were aboard during offshoretrawling on the south coast of South Africa, the mortality rate from deliberate Idlls was 0.018 sealsper trawl. Based on observations during 1992 and 1993 in South Africa, an estimated 212-424 furseals are killed annually during offshore demersal trawling, some possibly during inshore trawling,143 during midwater trawling, less than 825 during purse-seining and 14 during inshore drift netting(Wickens 1993, 1994a, b, submitted(a), (c), Wickens and Sims in press).


A number of attempts have been made to find efficient and humane methods of deterring sealsfrom fishing operations but none has proved successful for all fisheries (Wickens 1993, 1994b).Experiments in the early 1970's used explosive firecrackers but they were thought to disturb thefish and are therefore no longer used (Anon 1972, 1976, Shaughnessy et al. 1981, Wickens et al.1992). Electronic pulses and airguns, sounds of lciller whales and shots fired into the water (Anon1975a, b, 1977, 1978a) had no lasting effects. During demersal long-lining, lines were hauledfaster malcing it more difficult for seals to take fish and an inflatable boat was deployed throughoutthe hauling operation to pick up floating fish, disrupt the feeding behaviour of seals and to help inkeeping seals away from lines (Wickens et al. 1992). However, with the development of thefishery, seals adapted and dived further away and deeper to take fish from the lines.

A suggestion has been made that in, for example, the rock lobster hoopnetting fishery, achange to the baiting technique used in one particular area may reduce problems in others but thishas yet to be tested (Wickens 1993, 1994b, d). In addition, a method to alleviate the problem ofseals damaging propellers on some offshore trawlers is being investigated. Fish discardedoverboard - the target for seals - is minced finely malcing it inaccessible to seals (Wickens 1993,

1994b, Wickens and Sims in press).

Culling is not thought to be a solution because it is generally not large numbers of seals that

are involved; therefore some localised form of solution is required (Wickens 1993, 1994b, e, f).The shooting of seals is illegal in South Africa but it is an ongoing practice (Wickens et al. 1992,Wickens 1993, 1994b, submitted(a)) although there are problems with this as it is generally

51

considered to be in effective, places undue risk on the part of other fishermen working in the areaand is not considered to be a humane (Wickens 1993, 1994b, submitted (a)).

8. SOU

8.1 Species Situation

This area includes Australia and New Zealand (FAO areas 57 and parts of 71 and 81) wheretwo species of sea lion and two species/subspecies of fur seal are resident in this area. TheAustralian sea lion occurs on the southwest coast of Australia and has a stable population size of10 000 - 12 000 (Reijnders et al. 1993). It is listed in the IUCN Red List as "Rare". Hooker'ssea lion is found to the south of New Zealand and has a population size of 10 000 - 15 000(Reijnders et al. 1993). Incidental mortality during squid trawling and the life history of thepopulation is thought to be a threat to the Hooker's sea lion population (eg, Doonan and Cawthorn1984, Reijnders et al. 1993, Woodley and Lavigne 1993, 1994). Australian fur seals are foundalong the southeast coast of Australia and Tasmania with a population size of 35 000 - 60 000animals (Kirlcwood et al. 1992). A significant proportion of Australian fur seal mortality is throughentanglement and shooting (Shaughnessy and Warneke 1987). New Zealand fur seals are found onthe southwest coast of Australia and Tasmania and to the south of New Zealand with a populationof 134 700, that is increasing (Brothers and Pemberton 1990, Taylor 1990, Shaughnessy et al.1994)

All of the 4 pinnipeds found in this area (Australian and Hooker's sea lions and Australianand New Zealand fur seals) are involved in interactions with passive net and trap fishing, active netand line fishing and fish farming in this area. In addition, leopard seals from the Southern Oceanare possibly also involved in interactions with fish farms.

Fur seal bycatch occurs in all areas of the New Zealand zone south of 40°S but is mostprevalent off the west coast of the South Island, Snares Shelf, and the Puysegur and Bounty Islands.'Incidents' occur mostly on the edge of the continental shelf adjacent to rocicy shores that cansupport fur seal rookeries and haulouts. Forty five percent of the observed seal catch off the coastof the South Island was by vessels fishing for hake, not hold. There are large differences inbycatch off the west coast of the South Island with the highest rates occuring in waters deeper than500m south of Cape Foulwind (Gibson 1995). A potential threat to New Zealand fur seals is anincrease in fisheries activities because of incidental mortality (Reijnders et al. 1993).

IAN/PACIFIC OCEANS

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' I


8.2.1 Depredation


Australian fur seals are reported to maul salmon in set nets (Warneke 1979, 1982, Storr 1965,Warneke 1982) and Australian sea lions rob lobster pots as well as shark set nets (Robinson andDennis 1988, Goldsworthy and Shaughnessy 1994).

Active Net Fishing

New Zealand fur seals pull fish from hoki trawl nets in New Zealand (Mattlin and Cawthorn1991) and Hooker's sea lion are frequently observed taking squid from Auckland Island shelf trawlnets during retrieval and generally take squid from the side panels of the net as it is hauled alongthe surface of the water and aboard (Donoghue 1985). In 1993 for the whole zone there were anestimated 774 incidents involving about 1021 seals. There was an apparent decline in the numberof incidents between 1990 and 1993 which was probably the result of a large shift in the distributionof fishing away from areas where the incidence rate was better known. Also, vessels with moreexperience fishing within the zone tended to have lower incidence rates. However, lack of dataprevents firm conclusions about many of the relevant factors (Gibson 1995).

Fish Farming

Australian fur seals, and occasionally leopard seals (which occur in the Southern Ocean), takefish from salmon and trout farms in Tasmania, mostly during the night, particularly from thosefarms closest to seal-haul-outs (the seals involved generally are large subadult and adult males(Pemberton 1989, Pemberton et al. 1991, Pemberton and Shaughnessy 1993).

8.2.2 Gear Damage


Australian fur seals were reported to cause extensive damage to set nets in Victoria (Warneke1979, 1982).

Fish Farming

Australian fur seals attack salmon and trout farms in Tasmania to take fish and in doing sodamage the pens (Pemberton and Shaughnessy 1993).

53



Australian fur seals can cause fish to escape from set nets in Victoria and salmon and troutfarms in Tasmania (eg, Warneke 1979, 1982, Pemberton et al. 1991). Usually large quantities offish do not escape but on a few occasions there were large losses eg, 8 tonnes or 720 salmon andtrout, each between 1 and 3 kg (Pemberton and Shaughnessy 1993). Annual losses for 1986/87 wereestimated at between $10 000 and $175 000 per farm on 15 farms, with one farm losing more than$500 000 worth of fish in a year (Pemberton 1989).

Active Net Fishing

New Zealand fur seals are known to board hold trawlers in New Z,ealand via the stern rampwhich can disrupt activities (Mattlin and Cawthorn 1991).

Active Line Fishing

Australian fur seals were reported to disrupt line fishing for barracouta but this only seemsto be in seasons of short supply (Warneke 1979).



All of the 4 pinnipeds found in this area (Australian sea lions, Hooker's sea lions, Australianfur seals and New Zealand fur seals) are killed incidentally or deliberately during passive net andtrap fishing, active net fishing, passive line fishing and fish farming.

Hooker's Sea Lions

Incidental captures of Hooker's sea lions in squid trawls on the Aucldands Shelf are a concernfor the Hooker's sea lion population (eg, Doonan and Cawthorn 1984, Reijnders et al. 1993,Woodley and Lavigne 1993, 1994). Since the mid-1980's it is estimated that the annual kill is about110 Hooker's sea lions (74 - 163) of which about 72% are females which can therefore result inpups dying as well (Cawthorn 1985, Anon 1991a, Mattlin and Cawthorn 1991). The numbers ofHooker's sea lions that have been talcen in squid trawls are 95 (1978/79), 251 (1979/80), 239(1980/81), 323 (1981/82) and 309 (1982/83) (Donoghue 1985) and 143 (1986/87) and 43 (1987/88)(Anon 1991a).

Since January 1988, 2506 of 16 860 (14.8%) tows on the Auckland Island's shelf, and annulacoverage has varied from 9% in 1994 to 29% during 1993. Nine Hooker's sea lions were reportedIdlled in the 1994 southern squid trawl fishery; 3 by vessels with MAF observers and 6 by vessels

54

55

without observers. Since 1991 all position data of incidents has been known. The main fishery inthe area of interest is for squid but other species are also sought, eg, three Hooker's sea lions werecaught in 1993 by vessels targeting scampi. Using the data for observed vessels, the total annualmortality estimates for Hooker's sea lions for 1988-1994, assumming all catches were in area 6Tcan be estimated and is as follows (Baird 1995):

Australian Fur Seals

Australian fur seals drown in fish traps and lobster pots and trawls (eg, Warneke 1979, 1982,Goldsworthy and Shaughnessy 1994). Warneke (1975) reported that at Seal Rocks, 1.8% ofjuveniles retrieved were identified as having died in fishing gear while around Seal Rocks, 24% ofjuveniles retrieved were identified as having died in rock-lobster pots, fish traps and nets.

New Zealand Fur Seals

New Zealand fur seals are occasionally trapped and drown in set nets and lobster traps, trawlsfor barracouta on the west coast of the South Islands, trawls for hold on the east coast of the SouthIslands, and trawls for squid on the west coast of the South Island) and long-lines on the west coastof South Island) (Crawley and Warneke 1979, Woodley and Lavigne 1991, Reijnders et al. 1993,Mattlin 1994b).

New Zealand fur seals are caught in the hoki midwater trawl fishery in New Zealand (Anon1990e, 1991a, Mattlin and Cawthorn 1991, Mattlin 1994a). Forty are incidental Idlls were recordedin 1986, 52 in 1987 and 21 in 1988 (Anon 1990c), followed by a large incidental kill of 800-900seals in 1989 (Mattlin 1994a). After the implementation of guidelines in 1990 to reduce incidentalmortalities an estimated 596 (521-719) seals died (Mattlin 1994a). A further 172 (143-197) died in1991 and 160 (130-194) in 1992 (Mattlin 1994a). Although in 1989 it was common for there to bemultiple catches, thereafter there were fewer multiple catches, most catches being of single seals

(Mattlin and Cawthorn 1991). The probability of patching one or more seals in a haul has

Year Es ate Binomial Interval

1988 32.6 16-60

1989 140.8 98-200

1990 117.4 68-190

1991 20.6 3-71

1992 81.8 38-150

1993 7-36

1994 32.3 8-91

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decreased from 13.4% in 1989 to 2% in 1992 (Mattlin 1994a). The numbers of females caught havevaried from at least 38% in 1990 and at least 19% in 1991 to 57% in 1992 (Mattlin 1994a). Themajority of seals are caught at night and most appear to be taken as the gear is shot away and notas it is being hauled. Fur seals have learned to approach the trawler on hearing the noise of thewinch (Anon 1990c).


Australian Sea Lions

Australian sea lions were reported to be Idlled by fishermen if they were caught damagingnets (King and Marlow 1979) and many fishermen carry firearms for dealing with problem seals(Robinson and Dennis 1988).

Hooker's Sea Lion

In the northern part of their range, Hooker's sea lions are occasionally Idlled by fishermenand a few may be killed illegally for use as crab bait (Marlow and King 1979, Reijnders et al.1993).

Australian Fur Seals

Significant numbers of immature fur seals are shot by fishermen (Warneke 1975, 1979,Goldsworthy and Shaughnessy 1994, Reijnders et al. 1993) and around fish farms (Pemberton andShaughnessy 1993).

New Zealand Fur Seals

Some New Zealand fur seals are shot for no apparent reason while others are shot whenattacicing hooked tuna (Mattlin 1994b). The number shot is unknown but it is probably low basedon anecdotal information and the recovery of wounded or dead animals (Mattlin 1994b).


To avoid pinnipeds being taken in hoki trawls, it is recommended that trawlers deploy andretrieve their nets as quickly as possible, maintain the net below 150m depth, deploy a crewmember to observe any seal entanglement to ensure timely assistance for the animals, and at nightlights should be left on for a minimum period of time (Anon 1990c, 1991a, Mattlin and Cawthorn1991, Woodley and Lavigne 1993). The possibility of changing the fishing method to prevent thecapture of Hooker's sea lions, including escape panels in nets and having closed areas for fishing,has been discussed (Anon 1990e, 1991a). For 1993-1995 a catch limit of 63 Hooker's sea liondeaths (32 females) was set for the southern squid fishery and the operation of any vessel that killed3 sea lions would be reviewed. The industry would remove any vessel that killed 4 sea lions as a

voluntary measure (Baird 1995).

Shooting has been tried at Tasmanian fish farms but is only considered effective if - s arelcilled (Pemberton 1989, Pemberton and Shaughnessy 1993). Explosive seal crackers, protectionnets, emetics, pursuit by boats, lights and acoustic scarers have been used on seals around fishfarms in Tasmania but none is completely effective although the rate of attacks by seals may bereduced (Pemberton 1989, Pemberton et al. 1991, Pemberton and Shaughnessy 1993). Pembertonand Shaughnessy 1993 consider the use of emetics to be worth further research. The only methodof effectively reducing attacks is considered to be physically excluding seals but the cost of thismust be weighed up against the losses on those farms which are distant from seal haulouts(Pemberton et al. 1991).

9. CONCLUSIONS

9.1 Introduction

There are throughout the world interactions between pinnipeds and fishing operations. Thesevary greatly in extent and in their impact on either a fishery or pinniped population, ranges frominfrequent interactions in specific areas to large-scale problems causing population declines orsubstantial economic losses. Not all interactions are detrimental and it is not always the pinnipedsthat seek out the fishing operations. Although seals often feed in the vicinity of fish shoals, theyare attracted by fish already herded together or trapped in fishing gear, fishermen may also searchfor concentrations of pinnipeds as indicators of fish shoals.

9.2 Quantification of Interactions

The methods of collection of data from different regions and times is extremely variable, andundertaken for various lengths of time. These range from once-off questionnaire surveys, dock-sideinterviews, direct observations for particular periods of time to compulsory observer programmescovering a notable proportion of the fishing effort. For example there are compulsory observerprogrammes in the U.S.A. (eg, Perez and Loughlin 1991) and New Zealand (eg, Mattlin 1994b)which allow for the collection of large amounts of data, while in other areas, observation data arecollected for specific projects and for limited periods of time in, eg, South Africa (Wickens 1994b)and Japan (Wada et al. 1991). The accuracy of data collected using the different methods variesconsiderably and this huge variation in collection methods makes comparisons of interactionsbetween areas and times difficult.

Most of the interactions have a patchy distribution, being concentrated in certain areas.Extrapolation of figures sampled from an individual local fishery to the whole fishery is invariablyimpossible or requires careful interpretation if it is not to be misleading. The types and extent ofinteractions also vary seasonally and annually, maldng evaluations during specific years, possiblyrelating to certain fishing conditions, difficult to utilise more generally.

57

58

A number of the interactions between pinnipeds and fishing operations are difficult toquantify. For example, if seal activity causes a fish shoal to disperse that had been targeted by afishing operation, it is difficult to estimate the cost of this. If the fishery in question operates ona quota system and where the quota is likely to be filled, this loss of fish is measured in extrafishing time. Alternatively, in a non-quota fishery, the loss may be measured by the estimated valueof the fish lost. Another example is the presence of a seal that is caught in a net causing tears tothe net and a loss of catch. It is possible to estimate damage to nets but the loss resulting from tearsis generally small when compared to catch losses during the time required for repairs. In addition,the possible loss of fish that are deterred from the net by the presence of the seal, je, the time thatthe net is in the water but not worldng optimally, is also difficult to estimate.

There is no substitute for direct observations of fishing operations to quantify interactionsreliably because interactions are often exaggerated when detrimental to the fishery or underestimated when interactions are detrimental to the pinnipeds involved. For example, seals may beused as scapegoats for other factors such as inexperienced fishing techniques and seals may bedumped overboard and not recorded, or seals may be used as food for the fishermen, maldng itdifficult to distinguishing between incidental and deliberate catches.

9.3 Summary of Extent of Interactions

This review summarises cases of operational interactions between pinnipeds and fisheries orfish farms. Some of these may be severe in terms of the cost to the fishery or fish farm or in termsof mortality of a species. For others, they may be merely a record of an infrequent interaction thathas taken place. In all of the seven areas reviewed here, pinnipeds have, and may still be having,a detrimental effect on fishing operations and/or the fisheries may be affecting the pinnipeds (Tables2 and 3). From the total of 45 pinnipeds (species/subspecies), thirty-six have been recorded ashaving some interaction with fishing operations/fish farms. There are nine species/subspecies thathave no recorded interactions with fisheries/fish farms - the Galapagos sea lion and southernelephant seal, the freshwater Ungava, Ladoga, Caspian and Baikal seals and, from the SouthernOcean, the Subantarctic fur seal, Ross and Crabeater seal.

Fourteen species or subspecies have been recorded as involved in interactions affectingthemselves but not fisheries - the Guadelupe, Galapagos, Juan Fernandez and South American furseals, the Arctic ringed, Saimaa, ribbon, hooded and Atlantic bearded seals, northern elephant seals,the Pacific and Atlantic walruses, and from the Southern Ocean, the Weddell and Antarctic fur seal.Of these, the Guadelupe, Juan Fernandez and South American and Antarctic fur seals aredeliberately taken for bait, not incidentally during fishing, while the other species generally drownin fishing gear such as trawls and gill nets. There are no reported cases where pinnipeds affectfishing operations but suffer no detrimental effect as a result.

Incidental or deliberate mortality during fishing operations is considered a threat or a causefor concern for the whole, or part of the populations, of the "vulnerable" Steller's sea lion, SouthAmerican sea lion, the "vulnerable" Hooker's sea lion, the northern fur seal, the Australian fur

59

seal, New Zealand fur seal, grey seal, Eastern Atlantic harbour seal, Western Pacific harbourharp seal, the "vulnerable" Baltic ringed seal, "endangered" Saimaa seal, I3aikal , "endangered"Mediterranean monk seal and the "endangered" Hawaiian monk seal. The impact of pinnipeds onfisheries is of particular concern ,through depredation and gear damage during gill netting on thewest coast of North America, Japan, Britain, Scandinavia and Chile; through depredation, netdamage and disturbance at fish farms in the Britain and Chile, and depredation from trawls,depredation and gear loss from handlines, and disturbance of purse-seining in South Africa. Duringthe many other forms of fishing operation interactions are generally of minor importance.

All types of passive and active fishing operations and fish farming occur throughout thedifferent areas, with the exception of there is no fish farming in the South Atlantic/Indianarea (Tables 4 and 5).

There are some reported areas in which, although pinnipecls have a detrimental effect onfishing operations/fish farms, there are no reported parallel cases of these operations affectingpinnipecls, even through deliberate killing (eg, active line fishing and fish farming in the Canada,passive line fishing in South America and active line fishing in Australia). Likewise, not all casesof fishing operations affecting pinnipuls involve the pinnipeds in interactions detrimental to thefishing operations (eg, passive line fishing in Hawaii and New Zealand, active net fishing in Russiaand South America, and active line fishing in the South America). However, it is likely that in bothcases a two-way interaction does occur.

Based on the interactions summarised in this review, interactions appear to be more prevalentaround passive gear than active gear; this has also been the conclusion of others authors (eg, Mate1980, Beach et al. 1985, Gilbert and Wynne 1985, Gulland 1987, Harwood 1987).


Although many fishermen are convinced that culling is the solution to reducing problems withseals, the fact that interactions are often caused by a few seals (eg, Gulland 1987, Wickens 1994b)means that an overall reduction in the population size is not a general solution to relievingoperational interactions (eg, Northridge 1988, Wickens 1994b). A more appropriate option isgenerally considered to be methods that keep seals away from specific fishing operations. However,many methods have been attempted but with limited success.

Lethal methods have been attempted, including shooting seals, killing seals with a variety ofobjects and methods, sometimes involving poison. It is legal to shoot seals under certain conditionsin some countries, such as the Britain but illegal in South Africa, though here the shooting ofis commonplace. Lethal methods have not been found to be consistently effective means of lceepingseals from interacting with fishing operations. This is possibly because, if problems are caused bya few "rogue" seals, then removal of these animals should eliminate the problem. However, whenthe problem is caused by few, as opposed to many, individuals, then when this method removesindividuals they are then replaced by others (Harwood 1987).

,

e

§ = Also breeds in South America

60

Table 2 : Summary of reported cases, represented by X, of pinnipeds interacting with fishing operations throughdepredation, gear damage and disturbance either currently or historically. The shaded area indicatesoccurrence of the species in the area. The Southern Ocean species are given in outline text, thefreshwater species in italics and the asterisks indicate the following in terms of the 1993 IUCN Redlist: * = Insufficiently known, ** = Rare, *** = Vulnerable and **** = Endangered.

PINNIPEDS ---> FISHING OPERATIONS

Extant pinniped species1:

NortheastPacific

2:Northwest

Atlantic

3:NortheastAtlantic

Area4:

NorthwestPacific

5:South

Pacific /Atlantic

6:South

Atlantic /Indian

7:SouthIndian /Pacific

SouthernOcean

coco=coa)u)

Steller's (Northern) sea lion *** .California sea lion XGalapagos sea lion

South American (Southern) sea lion XAustralian sea lion ** XHooker's (New Zealand) sea lion *** X

(I)al0u)

=Li_,

Northern (Pribilof) fur seal

Guadalupe fur seal ***Galapagos fur seal

Juan Fernandez fur seal ***South American fur seal

South African (Cape) fur sealAustralian (Tasmanian) fur seal X

New Zealand fur seal XSuban rctic fursealAntarctic tur seal

(nCOa)co

2H

_u)0co2

Grey seal X XEastern Atlantic harbor (common) seal XWestern Atlantic harbor (common) seal XWestern Pacific harbor (Kuril) seal XEastern Pacific harbor (common) seal XUngava seal 4

Harp seal X XLarga (spotted) seal XArctic ringed seal

Okhotsk Sea ringed seal XBaltic ringed (Baltic) seal *4 I XSaimaa seal ***I'Ladoga seal *4 I

Caspian seal *4 4

Baikal sealRibbon seal

Hooded seal

Atlantic bearded seal

Pacific bearded seal XMediterranean monk seal **4 4 r

Hawaiian monk seal **4 I

Southern elephant seal§Northern elephant seal

Weddell s::Ross seal .

Cr L. eater seal, Leopard seal N

as Atlantic walrus

Pacific walrus

§ = Also breeds in South America

61

Table 3 : Summary of reported cases, represented by X, of fishing operations/fish farms causing mortality ofpinnipeds either currently or historically. The shaded area indicates occurrence species in the area. TheSouthern Ocean species are given in outline text, the freshwater species in italics and the asterisksindicate the following in terms of the 1993 IUCN Red list: * = Insufficiently known, ** = Rare,*** = Vulnerable and **** = Endangered.

FISHING OPERATIONS ---> PINNIPEDS

Extant pinniped species1:

NortheastPacific

2:NorthwestAtlantic

3:NortheastAtlantic

Area4:

NorthwestPacific

5:South

Pacific /Atlantic

6:South

Atlantic /Indian

7:South

Indian /Pacific

SouthernOcean

U)c0._asa)u)

Steller's (Northern) sea lion *** XCalifornia sea lion XGalapagos sea lion

South American (Southern) sea lion XAustralian sea lion ** XHooker's (New Zealand) sea lion *** X

(,)

rtsa)U)

zu_

Northern (Pribilof) fur seal

Guadalupe fur seal *** XGalapagos fur seal XJuan Fernandez fur seal *** XSouth American fur seal XSouth African (Cape) fur seal

Australian (Tasmanian) fur seal XNew Zealand fur seal Xsubentarctic fur sealAntarctic fur seal K

(i)

ala)cn

=

a.)=Ft_

Grey seal X XEastern Atlantic harbour (common) seal XWestern Atlantic harbour (common) seal XWestern Pacific harbour (Kuril) seal

Eastern Pacific harbour (common) seal

Ungava seal *

Harp seal X XLarga (spotted) seal X

XX.

Arctic ringed seal XOkhotsk Sea ringed seal XBaltic ringed (Baltic) seal *** XSaimaa sea/ **** XLadoga seal ***Caspian seal ***Baikal seal

Ribbon seal X XHooded seal X XAtlantic bearded seal XPacific bearded seal XMediterranean monk seal ****Hawaiian monk seal **** X

Sou), ern eleph nt seal §

Northern elephant seal

W .,,. I seal . KRoss se:,Crmbeater sealLeop:Ird 8: z KAtlantic walrus

Pacific walrus

Table 4 : Summary of reported cases of pinnipeds interacting with different types of fishing gear in different areasthrough depredation, gear damage/loss or disturbance either currently or historically, represented by X. Theshaded area indicates the occurrence of the type of fishing in the area.

Table 5 : Summary of reported cases of different types of fishing gear in different areas affecting pinnipeds throughmortality/entanglement either currently or historically, represented by X. The shaded area indicates theoccurrence of the type of fishing in the area.

PINNIPEDS -> FISHING OPERAT ONS

FISHING OPERATIONS -> PINNIPEDS

62

Area

7:SouthIndian /Pacific

Fishing gear type 1 :

N ortheasPacific

2:Northwest

Atlantic

3:NortheastAtlantic

4:N orthwes

Pacific

5:South

Pacific /Atlantic

6:South

Atlantic /Indian

7:South

I ndian /Pacific

Passive net and trap fishing X X

Active net fishing X X X

X

X

Passive line fishing X

Active line fishing X

Fish farrning X

Fishing gear type 1 :

N ortheasPacific

2:Northwest

Atlantic

3:Northeast

Atlantic

X

Area

4:N orthwest

Pacific

X

5:South

Pacific /Atlantic

X

6:South

Atlantic /Indian

Passive net and trap fishing X

Active net fishing X X

XPassive line fishing X X

Active line fishing X X X

Fish farming X

63

Non-lethal methods that have been attempted have included the use of acoustic harassmentdevices, many of which have been tested in various countries but with no lasting success. Inaddition various visual signals and chemical deterrents have been tested as a means of behaviourialconditioning to teach seals to avoid fishing gear.

The most successful mitigation measures that have been used are changes fishing gears orfishing methods where a particular change may reduce or exclude problems, thereby resulting ina permanent solution. These apply to some forms of interactions and have been used successfullyin, for example, the change to synthetic twine in gill nets which reduced damage by seals or theimplementation of anti-predator cages around fish farms. In some areas seals are seen as a nuisanc,ebut tolerated as an acceptable part of the risks involved in fishing, whereas in other places there isa gre,at demand for solutions to be found. Likewise, in some cases incidental catches of seals areunimportant in terms of the impact this may have on the population whereas in other cases thelevels of mortality may be unacceptable.

AC OWLEDGEMENTS

I would like to thank Michael Earle (Greenpeace) for the motivation for this project and RossShotton (FAO) for making the project possible. I am grateful to the various people who gavepersonal communications regarding the population estimates for different species - J. Gallo, A.Ponce de Leon, J. Francis, P. Majluf, M. Lima. Logistic support given by the Zoology Departmentof the University of Cape Town is gratefully acknowledged.

64

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