Post on 24-Apr-2018
Fish Conservation and
Management
CONS 486
Northern Atlantic Cod:
A management and conservation
failure
Chapter 12 Ross
Life history
• Mature at ~ 7 yrs
• > 30 yr max life
• Size at maturity: 50-100 cm (can be 2 m long!)
• Fecundity: 12 million eggs (compare to <10K for salmon!)
• Spawn on deep ocean shoals
Cod fisheries: rich in history
• the largest of its kind in the world
• was responsible for attracting Vikings and Basques (1000 years
ago, Basques fished for 400 years before other nations)
• 1600s – cod attracted French and British settlers to North
America (founding Canada)
• when Britain won control of the Atlantic maritime area after the
Battle of Trafalgar – cod made them the world power and
empire (why?)
• salted cod was the main dried food for use on ocean military
ships and was a major trading commodity (for slaves, rum,
sugar).
Cod fisheries: rich in history
• During the early to mid 1900’s, the cod fishery was the most important
economic and social component of Atlantic Canada
• arguably the resource most responsible and influential for the founding and
development of Canada
• in early 1960’s ~ 1-5 million tonnes of fish harvested per year
‘In Cod we Trust’
Cod fisheries: rich in history
• since 1992, fishery has been closed except for small localized fisheries
• In 2007, NFLD/Labrador stock listed as endangered by COSEWIC
– Other cod stocks listed as threatened or special concern
• Why the collapse?
Fishing approaches primarily used in inshore fishery:
• Trapnets (the cod trap)
• Machine jigging
• Hook-and-line
• Longlines
• Gillnets
Commercial catch data
• > 800,000 t peak harvest in 1968
• Declined steadily to a low of 140,000 t in 1978
• Suggests ‘growth overfishing occurring’
• BUT increased to 240,000 t in 1980s
• Collapsed in early 90s (resultant moratorium)
-caused by ‘discarding’ and non-reporting of this by-catch
-consistent with numerous accounts of discarding small cod
- Predation by seals also suggested as a cause but their
numbers were not increasing proportionate to the rapid
cod decline
More and more fish plants were built with funding from the
federal govt who also funded heavily in fleet development,
despite declining biomass of capture.
Role of Fish Behaviour• 1980s: abundance didn’t change much, why?
– Abundance estimated from fisheries catch surveys
– Abundance appeared higher due to behaviour!
• 1990s: new hydro-acoustic technology used to assess
abundance
– Revealed cod moving (southward and offshore) into areas
where the surveys and offshore fisheries were occurring!!
• Cod aggregations were concentrating…
– Fisheries yielded consistent catches
– Surveys likewise affected
Are cod recovering?
• Maybe, but slow - why?
• Competition: niche occupied by others (e.g. skates,
rays)
• Climate change not helping (oceans getting warmer)
• Bottom trawling destroyed spawning habitats
Bring out yer dead!
But I’m not dead yet..
Sometimes its hard to know if you are
winning or losing the imperilment game!
Echograms of cod from the acoustic surveys. Seabed is indicated in dark red, vertical blocks span
1 nautical mile (1852 m), and horizontal blocks span 50 m. In all cases, cod are distributed >100 m
off the bottom.
(a) June 1990 - migrating and spawning cod
in the Bonavista Corridor
(b) March 2008 - The first observed
aggregation in the Bonavista Corridor since
1992
(c) May 2014 - spawning aggregation in the
Bonavista Corridor
(d) May 2015 - spawning aggregation in the
Notre Dame Channel
Biomass estimated from
echograms of cod and their main
food capelin from the acoustic
surveys.
-Since 2011, abundance continues to
increase.
-Increase in food availability is major
reason.
-Older fish in population also have
better condition than in recent past.
-All signs of recovery under way……
The main factors that kick-started
the increase appear to be capelin
abundance and perhaps
immigration of at least one strong
year-class, which occurred during
a period of favourable climate and low
removals through the
fishery.
Rose G.A. and Rowe S. 2015. Northern Cod Comeback. Can. J. Fish.
Aquat. Sci. Vol. 72, 2015
“The main factors that kick-started the increase appear to be capelin
abundance and perhaps immigration of at least one strong year-class,
which occurred during a period of favourable climate and low removals
through the fishery.”
“With continued growth in the capelin stock and frugal management (low
fishing mortality), this stock could rebuild, perhaps within less than a
decade, to historical levels of sustainable yield. More generally, if this
stock can recover, the potential exists for recovery of many other
depleted stocks worldwide.”
What have we learned from the cod collapse?
Applied fisheries research:
• Don’t use commercial catch data to estimate stock sizes
• Research surveys now include acoustics which enables better
description of stock aggregations and movements
• Onboard observers, video surveillance of catch
What have we learned from the cod collapse?
Management strategies:
• Reduce and don’t encourage further capitalization
• Use risk-averse management decisions
– Precautionary approach, integrated mgmt.
• Do not harvest fish on spawning grounds
– i.e., protect spawning grounds
What have we learned from the cod collapse?
Advisory councils:
• East Coast Conservation Council: industry and govt reps who
examine data and advise Fisheries Minister
– Integrated Management: Transparent process for the
public and enables industry to buy-in to decision
Epilogue to the cod collapse: The Turbot War
-in 1994, Federal Coastal Fisheries Protection Act was passed
which among other things states that Canada has jurisdictional
rights to “straddling stocks”, countries that we had a current
NAFO dispute with (Spain, Portugal) were exempt, but March 3
1995 it was amended to include these countries.
-in past, disagreements over straddling stocks were an issue for
the World Court, but Canada bypassed this with the Act, which
set the stage for ‘Turbot War’
-March 6 1995, Fisheries Minister Tobin said he would arrest
any “pirate ships” fishing outside our EEZ on straddling stocks
The Turbot War
-on March 9, the Spanish fishing vessel Estai was fired upon by
DFO
-DFO/Coast Guard boats were cutting trawl nets off of fishing
boats if they weren’t allowed to board
-on March 10 Spanish warships were sent to protect their
interests
-on April 16 we came within 20 minutes of all out war
The Turbot War
-Canadian Destroyers ordered to sink any Spanish warship that
removed their gun covers
-Spanish fighter jets were making plans for refuelling in mid-air
over their “Falklands”
-bad weather saved the day and kept the Spanish fishing fleets
away from the Canadian vessels
-the following day Spain agreed to NAFO suggested
conservation measures including observers on their boats and
Canadian inspections, in return they got an increase in that
year’s quota of some species
Life history
• Mature at ~ 3 yrs, > 30 yr max life
• Fecundity ~ 1 million eggs
• Size at maturity ranges from 50-100 cm
• Anadromous, spawning in rivers, rearing in estuaries and
coastal areas along the New England and Carolinian coasts
• Many similar attributes to cod: life span, fecundity, size, but
differ with much early age at maturation and are anadromous
History
• Since 1700s, important commercial species on East
coast
– Recreational species since early 1980’s
• Hook and line gear predominates in both fisheries
• In 1972, US commercial landings peaked ~ 6000
tons then dramatically collapsed
• In Canada:
• St. Lawrence Estuary population is extinct
• Bay of Fundy and Gulf of St. Lawrence
populations ‘threatened’
• In 1995, US stocks were declared “recovered’’!
• Why did US pops collapse and recover?
• Declining abundance of outmigrating smolts to the ocean in Maryland and commercial
landings both showing similar patterns (large declines from early 70s to early 90s)
• The science survey data are of good quality, and have been collected for decades
prior to the decline.
• Poor juvenile survival was a result of lower number of returning adults and freshwater
habitat problems.
• Female abundance from spawning grounds showing reduced numbers
starting in mid 70s reaching low point in mid 80s.
• The long term dataset enabled managers to determine what historical levels
probably should be, thus could set a restoration goal.
• This goal was important as part of the restoration/recovery plan for the
species.
• in 1982, by chance, a modestly
abundant 8 year group appeared on
spawning grounds
• the management system immediately
protected those potential spawners
through min-size limits
• 3-4 years later, their babies arrived on
spawning grounds and those young
to mid age classes started to be seen
every year
Ability to take advantage of a lucky break!
Compliance with min size limits
• recreational fishers complied with the min size limits imposed on the
1982 age class and started releasing a lot more fish to the point that
almost all were being released by early 90s.
• this tactic caused an increase in CPUE, and an increase in catch per trip
so anglers were very happy!!
What sequence of events turned the collapse around?
Atlantic States Marine Fisheries Commission (ASFMC – 13 states involved)- 1977 ASMFC developed plan - not all states bought in
• Pressure from commercial sector• Stocks continue to decline…
- 1981 min size limits (14” in bays and 24” along coast) and area closures• Resistance, continued decline..
- 1984 federal passage of Striped Bass Act• State govs can normally do what they want with fisheries but threat of federal
penalties = compliance
- 1984/1985 moratorium placed on 1982 age class• Strong class that needed protection• Annual increases in minimum size limit protect ‘8s class
- 1995 juveniles back to levels they were at in late 60’s• ASMFC wants to decrease minimum size which is now at 36” down to 28” but
anglers want it to stay!• Example of user groups engaged in conservation
• Scientific spawning ground data used to show trends and help managers
set thresholds of recovery and upper end targets, anything above the
SSB target is surplus for harvesting.
• The ability to set reference points using scientific data, models, etc is
important and unique.
Scientific surveys also included ocean trawls
• Now managers can respond quickly to reduce harvest if warranted