AD-A235 074 ENVIRONMENTAL IMPACT

1I1111 IN 1111111111111 111 ll J 1i ul J1l RESEARCH PROGRAMTECHNICAL REPORT EL-89-10

SPECIES PROFILES: LIFE HISTORIES ANDENVIRONMENTAL REQUIREMENTS OF COASTAL

VERTEBRATES AND INVERTEBRATESPACIFIC OCEAN REGION

Report 5

THE PARROTFISHES, FAMILY SCARIDAE

by

R. E. Brock

SeaGrant College Program and. _Hawaii Institute of Marine Biology

University of HawaiiP.O. Box 1346, Coconut Island

Kaneohe, Hawaii 96744

,A DTIC-..SELECTE" " " " J "i ) APR 25 19911

March 1991Report 5 of a Series

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11. TITLE (Include Security Classification) Species Profiles: Life Histories and Environmental Requirementsof'Coastal Vertebrates and Invertebrates, Pacific Ocean Region; Report 5, The Parrot-fishes. Family Sgaridap_

12. PERSONAL AUTHOR(S)

Brock, R. E.13a, TYPE OF REPORT 13b. TIME COVERED 14. DATE OF REPORT (Year, Month, Day) 15. PAGE COUNT

Report 5 of a Series FROM _ TO March 199116, SUPPLEMENTARY NOTATION

Available from National Technical Information Service, 5285 Port Royal Road, Springfield,VA 22|]

17. COSATI CODES 18. SUBJECT TERMS (Continue on reverse if necessary and Identify by block number)

FIELD GROUP SUB.GROUP Ecological role Life historyEnvironmental requirements ParrotfishesFisheries-

19. ABSTRACT (Continue on reverse if necessary and Identify by block number)

Parrotfishes are highly colorful species inhabiting coral reefs of the world's trop-ical seas. They may usually be identified by the fused teeth forming a massive beak whichis used in rasping the substratum for food materials. With growth, many species gothrough a number of color phases and adults usually have marked color and morphologicalsexual dimorphism. These characteristics have resulted in considerable confusion in thetaxonomic literature; there are about 68 species of parrotfishes worldwide. Little isknown about the life history of parrotfish; apparently many species spawn at discretetimes and locations and eggs and larvae are pelagic, returning t ; he adult habitat afterseveral weeks in the plankton. With growth these fishes display sex reversal and dichro-

matism; the largest fish are usually terminal-phase males.

Parrotfishes are primarily herbivorous, feeding on microalgal resources. The heavybeak is used to rasp algal materials from the hard coralline substratum; once ingested all

rnnt f nit)

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University of HawaiiSeaGrant College Program andHawaii Institute of Marine Biology

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PO Box 1346, Coconut IslandKaneohe, HI 96744

19. ABSTRACT (Continued).

food passes to the pharyngeal mill, which is equipped with a set of opposing teeth thatgrind and pulverize all food materials. In feeding, parrotfishes consume microalgae aswell as cryptobiota (small cryptic invertebrates) which provide a source of protein.Studies suggest that there is considerable overlap in the algal resources consumed bysympatric parrotfish species; however, competitive trophic interaction is low because ofthe high turnover characteristics of the microalgal resource. In feeding, parrotfishesingest considerable carbonate material resulting in the production of 400 to 2,000 kg ofcalcium carbonate material per hectare per year. Thus these fishes are important in theproduction and redistribution of sediments on reefs.

Through their feeding activities, parrotfish clear the substratum of algae (whichcompete with corals for space) thus increasing the successful recruitment of corals aswell as promoting the growth of encrusting coralline algal species. Studies suggest thatparrotfishes play an important role in maintaining benthic community structure in theirnormal field densities, hence they are considered to be "keystone species" on coral reefs.

Parrotfish are caught and consumed by many fishermen; loss of these fishes may resultin local changes occurring in benthic communities, shifting from coral-dominated to algal-dominated systems. It is suggested that conservation and management of these importantfishery resources are probably best carried out by incorporating modern concepts with tra-ditional management strategies developed by the local indigenous culture. The challengeconfronting the modern resource manager is to integrate traditional and modern strategiesinto a format that is politically and culturally acceptable.

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PREFACE

This report is designed to provide coastal managers, engineers, andbiologists with a brief comprehensive sketch of the biological characteristicsand environmental requirements of the parrotfishes (Family Scaridae) and todescribe how populations of the species in Hawaiian waters may be expected toreact to environmental changes caused by coastal development. This report hassections on taxonomy, life history, ecological role, environmental require-ments, growth, exploitation, and management.

This work was part of the Environmental Impact Research Program (EIRP),sponsored by Headquarters, US Army Corps of Engineers (HQUSACE), under EIRPWork Unit 31627. Technical Monitors were Dr. John Bushman, Mr. David P.Buelow, and Mr. David Mathis of HQUSACE.

This report was prepared by Dr. R. E. Brock of the SeaGrant CollegeProgram and Hawaii Institute of Marine Biology, University of Hawaii.

The author gratefully acknowledges reviews by Drs. Douglas G. Clarke andMark W. LaSalle of the Coastal Ecology Group (CEG), Environmental Laboratory(EL), US Army Engineer Waterways Experiment Station (WES), and Mr. Mike Lee ofthe US Army Engineer Division, Pacific Ocean.

M1r. Edward J. Pullen, CEG, served as Contract Monitor for this studyunder the general supervision of Dr. Conrad J. Kirby, Chief, EnvironmentalResources Division, EL, and Dr. John Harrison, Chief, EL. Dr. Roger T.Saucier was the EIRP Program Manager. This report was edited by Mrs. JaneanShirley of the Information Technology Laboratory, WES.

Commander and Director of WES during preparation of this report wasCOL Larry B. Fulton, EN. Dr. Robert W. Whalin was Technical Director.

This report should be cited as follows:

Brock, R. E. 1991. "Species Profiles: Life Histories and Envi-ronmental Requirements of Coastal Vertebrates and Invertebrates,Pacific Ocean Region; Report 5, The Parrotfishes (Family Scaridae),"Technical Report EL-89-1O, US Army Engineer Waterways ExperimentStation, Vicksburg, MS.

AOoesslon For

NTIS GRAMIDTIC TABUnaninoioed -:ustiticatlon

t o ) 37\ % Distribution/

Avallabllity Codes

'Avail and/orNegt Speolal

iii

CONVERSION TABLE

Metric to U.S. Customary

Multiply By To Obtain

millimeters (mm) 0.03937 inchescentimeters (cm) 0.3937 inchesmeters (m) 3.281 feetmeters (m) 0.5468 fathomskilometers (km) 0.6214 statute mileskilometers (km) 0.5396 nautical miles

square meters (m ) 2 10.76 square feetsquare kilometers (km2) 0.3861 square mileshectares (ha) 2.471 acres

liters (1) 0.2642 gallonscubic meters (m3 ' 35.31 cubic feetcubic meters (m) 0.0008110 acre-feet

milligrams (mg) 0.00003527 ouncesgrams (g) 0.03527 ounceskilograms (kg) 2.205 poundsmetric tons (t) 2205.0 poundsmetric tons (t) 1.102 short tons

kilocalories (kca ) 3.96g British thermal unitsCelsius degrees ( C) 1.8( C) + 32 Fahrenheit degrees

U.S. Customary to Metric

inches 25.40 millimetersinches 2.54 centimetersfeet (ft) 0.3048 metersfathoms 1.829 metersstatute miles (mi) 1.609 kilometersnautical miles (nmi) 1.852 kilometers

square feet (ft2 ) 0.0929 square meters

square miles (mi ) 2.590 square kilometersacres 0.4047 hectares

gallons (gal) 3 3.785 literscubic feet (ft) 0.02831 cubic metersacre-feet 1233.0 cubic meters

ounces (oz) 28350.0 milligramsounces (oz) 28.35 gramspounds (lb) 0.4536 kilogramspounds (lb) 0.00045 metric tonsshort tons (ton) 0.9072 metric tons

British thermal unit8 (Btu) 0.2520 kilocaloriesFahrenheit degrees ( F) 0.5556 (OF - 32) Celsius degrees

iv

CONTENTS

Page

PREFACE............ ................................................ iii

CONVERSION TABLE .................................................... iv

NOMENCLATURE/TAXONOMY/RANGE...........................................1I

MORPHOLOGY/IDENTIFICATION AIDS...............* .................. 3

LIFE HISTORY ........................................................ 4

Reproduction....................................................... 4Eggs and Larvae.................................................... 6Recruitment ............ ..... ..................................... 6Food and Feeding................................................... 7Growth............................................................ 10

ECOLOGICAL ROLE ..................................................... 11

Behavior ......................................................*****11Sediment Production .......................................... 11Interaction with Other Herbivorous Species........................... 12Role In Structuring Benthic Communities ............................. 13

ENVIRONMENTAL REQUIREMENTS ........................................... 13-

FISHERY............................................................. 14

RECOMMENDATIONS FOR CONSERVATION...................................... 14

REFERENCES.......................................................... 16

PARROTFISHES, FAMILY SCARIDAE

NOMENCLATURE/TAXONOMY/RANGE as diagnostic features; fin ray,scale, and gill raker counts that

For more than a century the par- are useful in identifying mostrotfishes have been known as one of fishes are of limited use in thethe most difficult and confusing recognition of many scarid species,families of reef fishes in system- leaving color as one of the fewatic ichthyology (Schultz 1958; usable characters. However, the useRandall 1963a and b). The recogni- of color complicates comparativetion of species is often uncertain work with long-preserved specimensand the descriptions provided in the (Schultz 1958). The use of color asliterature are in many cases inade- an identifying character is furcherquate. Not until Schultz's (1958) complicated by the sexualmonumental effort had anyone dichromatism that is found ir, manyattempted a revision of the family parrotfish species (Choat andon a worldwide basis. Since the Robertson 1975; Robertson and Warnerpublication of that revision, there 1978).have been a number of papers locallyrevising the parrotfishes. Because The value of color in distin-of the taxonomic confusion and guishing various parrotfish speciesapparent similar behaviors and has been recognized by a number ofinfluences in the coral reef com- ichthyologists. Smith (1956) notesmunity which are detailed below, ..."There is probably not a singlethis species profile was written to work based on preserved material ofprovide a general review of the the parrotfishes whose list of syn-parrotfish family Scaridae rather onymy is worth any great consider-than focusing on a single species. ation. It is ludicrous to expendExamples of Hawaiian parrotfishes time and effort in attempting toare shown in Figure 1. deduce what species earlier workers

really had, and to attempt to fitCharacters that are of use in material into their utterly inade-

differentiating species of parrot- quate definitions... In attempting tofishes include (a) the number of fit numbers of parrot fishes intorows of scales on the cheek, (b) the existing species it became clearnumber of scales in the ventral row that adequate and accurate defini-on the cheek, (c) the number of rows tion and portrayal of our materialof teeth on the pharyngeal bones, would be of far greater value than(d) the number of median predorsal any names. In consequence everyscales, (e) the number of pectoral effort was made to prepare the full-rays, and (f) the color pattern. est possible notes as well asThese alone are usually insufficient sketches of the live colors and

1

.7V

WWI,

U)Y

0f) f

markings..." Thus recent taxonomic geographic distributions but otherstreatments of the parrotfishes often are apparently restricted indicatingpresent the color photographs of the the occurrence of some endemism atspecies. However as noted by Bruce the species level.and Randall (1985), the sexuildichromatism and color changes tiUa: Recent regional taxonomic worksoccur with growth were not recog- encompassing parrotfishes includenized until relatively recently. those for the Red Sea and WesternThus duplication in names is common Indian Ocean (Smith 1956, 1959,and the color descriptions often are 1965; Jones and Kumaran 1980;not diagnostic. Randall and Bruce 1983), the Eastern

Pacific (Rosenblatt and Hobson 1969)Within the parrotfishes two sub- the Central, Western, and South

families have been defined: the Pacific (Schultz 1960, 1969;Scarinae and the Sparisomatinae. Marshall 1964; Munro 1967; Bagnis etSchultz (1969) recognized seven al. 1972; Yang 1979; Randall andgenera in the Sparisomatinae includ- Choat 1980; Randall 1981; Bruce anding Calotomus, Leptoscarus, Randall 1985; Shao and Chen 1989)Cryptotomus, Nicholsina, Euscarus, and the Caribbean (Randall 1968).Sparisoma and Scaridea. Bruce andRandall (1985) treated the monotypicgenus Scaridea as a synonym of MORPHOLOGY/IDENTIFICATION AIDSCalotomus. Some authors (e.g.,Bruce and Randall 1985) regard Members of the family may beEuscarus as a synonym of Sparisoma. recognized by the following charac-Most of the parrotfish species are ters: teeth fused or coalescedfound in the subfamily Scarinae forming a pair of dental platesunder which Schultz (1958, 1969) separated by an obvious midlinenoted four genera: Scarops, suture; external canines may beBolbometopon, Ypsiscarus and Scarus. present; gill membranes broadlyRandall (1981) has placed the mono- joined to the isthmus; cheek scalesspecific genus Scarops under Scarus. in one to four rows; medianThus in the classification of par- predorsal scales three to eight inrotfishes, we find the following number; dorsal rays IX, 10; analgenera generally recognized: 111,9; pectoral rays ii,11 to ii,Calotomus, Leptoscarus, Cryptotomus, 15; branched caudal rays 6 f 5;Nichoisina, Bolbometopon, Ypsiscarus paired upper pharyngeal bones withand Scarus. one to three rows of molarlike teeth

and a single lower pha-yngeal boneParrotfishes are found in all bearing rows of molarlike teeth.

tropical oceans of the world. Thetaxonomic confusion with the family In the field, most scarids may bemakes the determination of easily recognized by their fusedgeographic range of many species teeth presenting an appearance simi-difficult; in his early work, lar to a parrot's beak, largeSchultz (1958) noted 354 scientific scales, and often bright colors.names from the literature proposed These fish may travel in mixedfor species in the family but Found schools or singly and are often seenonly 80 valid species. More browsing on the substrate. Becauserecently, Schultz (1969) listed 68 of the confusion in the taxonomy ofspecies of parrotfishes; these are the family, the appropriate afore-distributed across the tropical mentioned taxonomic works should beAtlantic, Indian, and Pacific Oceans consulted in determining speciesas well as into the Red Sea. Many locally present.species appear to have wide

3

LIFE HISTORY genera Sparisoma, Scarus andCryptotomus were found to be

Reproduction protogynous (Robertson and Warner1978). Apparently, the relative

Parrotfishes typically show a proportions of primary and secondarysexual dichromatism as noted above; males may vary widely among species.color changes with size were first Some are monandric where all malesnoted by Parr (1930). Sexual are derived from females by sexdichromatism was established for a change while other species may lackHawaiian scarid species (Scarus the development of any secondaryperspicillatus) in 1954 where males.females are reddish brown and malesare blue-green (Brock and Yamaguchi The relationship between sex and1954). Protogynous sex reversal in color pattern in scarids is complex.scarids was first documented by The most common situation is whereReinboth (1968) although earlier two adult color patterns exist in awork had suggested that it may species; terminal-phase males withexist. In general the sex change in bright colors (blues, greens, reds,parrotfishes is similar to those and yellows) and initial-phase malesseen in wrasses; at a cellular and females that are characterizedlevel, ovaries of functional females by drab combinations of greys,may possess spermatogenic cells browns, and black. Examples of thisalong the ovarian lamellde which dichromatism have been documented inexpand during sex reversal while Scarus, Sparisoma, Nicholsina,oogonia degenerate. Males in many Bolbometopon and Cryptotomusscarid species can be either primary (Thresher 1984). However, monochro-(i.e., born male) or secondary matic species do exist (Randall(derived from females). Primary and 1968; Rosenblatt and Hobson 1969;secondary males differ in gonad Choat and Robertson 1975); largestructure where the testes of pri- males in at least two speciesmary males lack any indication of (Scarus coeruleus and S. perrico)having arisen from ovarian tissue may be differentiated by variationwhile in secondary males remnants of in morphological characters (i.e.,ovarian lumen are present. larger forehead humps in large males

than encountered in females;Sex reversal or sequential Rosenblatt and Hobson 1969). In

hermaphroditism may be responsible other species such as Scarusfor the haremic mating systems seen rubroviolaceus, large males developin many scarid species where large more lunate tails (elongated fila-males keep a harem of smaller ments on the caudal), a feature lessfemales, which favors a sex reversal obvious in females and smaller malesfrom' female to male with greater (Thresher 1984). Finally, variationsize (Warner 1984). from the usual scarid pattern of

dichromatism is the development ofReinboth (1968) noted protogyny specific color patterns in large

in seven species of Western Atlantic females of Scat-us compressusand Eastern Pacific parrotfishes in (Rosenblatt and Hobson 1969;the subfamilies Scarinae and Thresher 1984).Sparisominae. Sixteen Great BarrierRecf Scarus species were found to be Spawning n ,ost pa rot F>hesprotogynous (Choat 1969; Choat and appears to occur throughout the yearRobertson 1975) as well as Scarus but the peak is usually centered onsordidus in Japan (Yogo, Nakazono, the summer months (Randall andand Tsukahara 1980). Similarly, Randall 1963; Colin 1978; Robertson10 Western Atlantic species in the and Warner 1978). Watson and Leis

4

(1974) found that Hawaiian scarids female with the male's fins extendedappear to spawn in the period from or displayed by "bob swimming"April through July. In contrast (Thresher 1984) around the female.Reeson (1983) noted that Caribbean Spawning occurs when the femalescarids appear to spawn throughout moves from the bottom and thethe year with more intense spawning closely associated pair make a shortactivity being confined to the and fast spawning ascent of aboutcooler months of the year. However, 3m, release their gametes at thenon-ripe scarids may be present over apex of this rush, and quicklythe annual cycle suggesting that return to the substratum. Pairdiscrete non-spawning periods exist spawning in scarids has been(Robertson and Warner 1978). described by Winn and BardachJohannes (1978, 1981a) has noted (1960), Randall (1963a), Randall andthat many coral reef fish species Randall (1963), Rosenblatt and Hob-including scarids spawn on the lunar son (1969), Buckman and Ogdencycle but spawning may be associated (1973), Barlow (1975), Yogo, Naka-with peak tides (Thresher 1984). zono, and Tsukahara (1980), and

Thresher (1984).Migration to specific spawning

sites seaward of the fringing reef Group spawning usually involvesis common among parrotfishes but is from 3 to 20 initial-phase fish andnot a universal characteristic. The has been described for two Sparisomamovement of scarids to spawning and eight Scarus species (Randallsites may occur throughout the day; and Rardall 1963; Barlow 1975; Choathowever, spawning usually takes and Robertson 1975; Bruce 1978;place in the afternoon (Randall and Colin 1978; Robertson and WarnerRandall 1963; Colin 1978; Robertson 1978; Yogo, Nakazono, and Tsukaharaand Warner 1978). There is 1980). In group spawning, initial-variability in the time of spawning phase males and females arrive atwhich may be a function of local the spawning site and mill about incurrent patterns, i.e., at peak high aggregations until some criticaltides for the dispersal of eggs by group size is attained. Withintidal currents (Choat and Robertson these aggregations, small numbers of1975; Yogo, Nakazono, and Tsukahara individuals break away, forming1980). tight schools; together these small

groups accelerate upwayd severalSpawning in scarids may occur meters, release their gametes, and

either by pairs or in groups. Pair abruptly return to the bottom.spawning involves a single male and Colin (1978) found that thesefemale and is probably universal in tightly aggregated groups take asthe family (Thresher 1984); pair little as 0.45 sec to complete thespawning has been reported in most spawning rush and swim at an averageof the species that have been stud- speed of 40 kmhr'.ied including members of the follow-ing genera: Cryptotoinus, Sparisoma, For a given scarid species, bothBolbometopon, and Scarus. Typi- pair and group spawning will occur;cally, terminal-phase males arrive the proportion of the populationat the spawning area and establish engaged in one type of spawning willwell-defended territories. Later, vary widely (Warner 1984).initial-phase males and temales Sparisoma rubripinne usually repro-arrive and roam through the territo- duces through group spawning in theries; some fishes are chased away Virgin Islands (Randall and Randall(presumably males) and others are 1963) but pair spawning is the normcourted by the terminal-phase males. for this species off tile PanamanianCourtship may involve circling the coast (Robertson and Warner 1978).

5

Apparently there is a basic Once hatched, larval scaridsflexibility in the scarid socio-sex- become part of the neritic planktonual system; different behaviors may (Watson and Leis 1974; Young, Leis,be manifested under different eco- and Hausfeld 1986). While in thelogical conditions (Barlow 1975). plankton, scarid larvae (like theFactors which may influence the larvae of many other coral reef fishlocal reproductive strategy include species) probably remain within athe availability of spawning sites, reasonable distance from the adultpopulation density, seasonal habitat through entrainment in oceaneffects, and water temperature. The mesoscale eddies and currents (Lobelrelative success of the various and Robinson 1983, 1986). Thissexual phases in scarids (i.e., strategy presumably reduces preda-primary, secondary, initial-phase tion on the larvae and allows for aand terminal-phase males) may be due return of individuals to the reefto each being reproductively supe- habitat (Johannes 1978). The lengthrior under a certain set of ecologi- of larval life in scarids rangescal conditions (Robertson and Warner from 41 to 48 days (Brothers,1978). The flexibility in scarid Williams, and Sale 1983).reproductive systems may, in part,explain the success of this familyon coral reefs. Recruitment

Eggs and Larvae Thus after about 7 weeks, scaridlarvae recruit to the adult habitat.

Little is known about the eggs or Many coral reef fishes at the timelarvae of parrotfishes. Winn and of settlement will undergo aBardach (1960) noted that the metamorphosis, often gaining pigmen-pelagic eggs of two subfamilies tation and changing in body form to(Scarine and Sparisomine) show mor- become a juvenile. Parrotfishes dophological differences: Scarine so, with most species on settlementeggs are spindle-shaped, 2.4 to having a similar appearance: drab3.1 mm in length and are transparent green to brown coloration, oftenwith a yellow oil droplet. Watson with horizontal stripes (Matsuda andand Leis (1974) provide a similar Tanaka 1962). The dearth of morpho-description. Sparisomine eggs are logical variation confounds speciesspherical, range in diameter from identification of juvenile scarids0.6 to 1.1 mm, and have a single (Bohlke and Chaplin 1968). Juvenileyellow to orange oil droplet parrotfishes are often found in(Randall and Randall 1963). small foraging schools and are an

important prey for many predatoryThe eggs of Sparisoma rubripinne reef fishes (Randall 1963b; Starck

hatch in about 25 hours in a water and Davis 1966; Brock 1972; Ogdentemperature of 26 C (Randall and and Buckman 1973; Reeson 1983).Randall 1963). lhese authors reportthat the newly hatched larva of Large variation in the abundanceS. rubripinne is about 1.7 mm long, of fish recruiting to coral reefs ishas a prominent yolk sac, and lacks typical of many reef systems (Kamifunctional eyes, mouth, or antis. and Ikehara 1976; Luckhurst andThe larvae are weak swimmers and Luckhurst 1977; Russell, Anderson,subsist on yolk reserves until those and Talbot 1977; deBoer 1978; Mollesdisappear and the mouth opens in 1978; ralbot, Russell, and Andersonabout 3 days. Randall and Randall 1978; Williams 1980; Williams and(1963) described 12 developmental Sale 1981; Kock 1982; Doherty 1983;stages over the 159 hours of Williams 1983; Walsh 1984). Data onobservation. the recruitment rates of

6

parrotfishes are few; Sale et a]. other reducing the size of ingested(1984) note that recruitment rates materials. The teeth set in thein Scarus sordidus on Australian pharyngeal bones are constantlyreefs varies from 2.6 to 17.3 being produced in the alveolarindividuals per 100 m2 . Such cavity anterior to the mill. Poste-variability is an important factor rior to the pharygneal mill is theinfluencing the fish community esophagus, separated from the intes-structure on reefs. Victor (1983) tinal tract (duodenum, ileum, andfound that even with nearly continu- rectum) by a pyloric valve (Goharous spawning in a labrid species, and Latif 1959). Notably absent inthe recruitment was sporadic, sug- parrotfishes is a stomach and thegesting that the pelagic environment thin-walled gut is slightly acidichas an unpredictable effect on containing carbonic anhydrase (Smithrecruitment, and Paulson 1974, 1975).

In Hawaiian waters newly settled There has been a long-standingparrotfishes are seen from early controversy over whether scaridsFebruary through October. Walsh feed on live corals or just rasp(1984) found evidence of greater algae and cryptofauna (organismsrecruitment in scarids during the residing within coralline substrata)summer than at other times of the from the hard substratum. Thisyear on Kona, Hawaii reefs. controversy began with Darwin's

(1845, 1890) observations at Cocos-Food and Feeding Keeling Islands that these fishes

feed on live corals. Forbes (1885)Parrotfishes have received much made the same observation at the

attention in the literature on Cocos-Keeling Islands. Finckhtropical reefs because of their pur- (1904) at Funafuti Atoll in Tuvaluported role in feeding on corals determined that parrotfishes feed on(Randall 1974). There is, however, algae only. Verwey (1931) notedlittle quantitative data on food that three scarid species at Bataviapreferences for members of the fam- were algal feeders but Al-Hussainiily Scaridae. This is due in part (1947) listed four species ofto the difficulty of identifying and Pseudoscarus in the Red Sea as coralquantifying ingested food material feeders. Suyehiro (1942) recordedbecause it is pulverized by the one Japanese species as feeding onlypharyngeal mill, a structure charac- on algae. Newell et al. (1951) interistic of the parrotfish family the Bahamas and Newell (1956) foundScaridae. Parrotfishes typically that Tuamotuan scarids fed on algaehave a rasping beak (Figure 1) com- and took a layer of limestone inprised of teeth fused into upper and doing so; in Kiribati, Cloud (1952)lower dental plates in all but the noted the same thing. Emery (1956)most primitive genera (Schultz 1958) at Johnston Atoll found that coraland the beak is used in scraping made up 25 percent of the stomachhard substrata for food materials contents of Scarus perspicillatus(primarily microalgae). Once and Hiatt and Strasburn (1960) iningested, all food passes into the the Republic of the Marshallspharyngeal mill consisting of two recorded nine parrotfish speciesupper and one lower grinding sur- (including Scarus sordidus) feedinqfaces into whizh are set the pharyn- principally on corals. Gohar andgeal teeth. These opposing teeth Latif (1959) ascertained that coralform a concave-convex surface which was a major constituent of the foodgrinds, pulverizes, and triturates of three parrotfish species in theall food materials. Strong muscles Red Sea. Stephenson and Searlesmove the grinding surfaces over each (1960) on the Great Barrier Reef

7

found no coral in the stomachs of 60 percent of the volume of mate-three scarids and Choat (1966) never rials consumed for all species.saw parrotfishes at Heron Island Animal remains included harpacticoid(Great Barrier Reef) feeding on live copepods, mysids, amphipods,corals. In the West Indies, Randall shrimps, sponges (Cliona spp.),(1967) determined that of 10 species bryozoans, tunicates, micromollusks,of parrotfishes examined, only two foramiiiferans, and most commonly,species had a very small amount of polychaetes. On Caribbean reefslive coral present in their (Barbados) Frydl and Stearn (1978)stomachs. Glynn (1973) has seen one found scarids consuming micro-scarid species feeding on live mollusks, foraminifera, andcorals off the Pacific coast of echinoderm parts (Diadema) alongPanama and Glynn, Stewart, and with carbonate substratum. RandallMcCosker (1972) list three species (1967) noted that 6 of 10 Caribbeanfrom the same locality as coral parrotfish species examined hadfeeders. Hobson (1974) found no consumed some animal remains includ-evidence of coral feeding amongst ing fragments of gorgonians,scarids examined off the Kona, sponges, echinoids, corals, crusta-Hawaii coast; however, Randall ceans, and mollusks as well as fora-(1974) and Brock (1979b) note that minifera. However, in none of theseScarus perspicillatus does occasion- Caribbean species did the volume ofally feed on live coral in the animal material exceed 2.8 percentHawaiian Islands. In Barbados, of the total. Many of the organismsFrydl and Stearn (1978) found that consumed by parrotfishes are small,only one of six parrotfish species residing in the coralline substratumstudied consumed live coral. In six and are collectively known as thespecies of Okinawan scarids examined cryptobiota. The biomass ofby Sano, Shimizu, and Nose (1984) cryptobiota may range from 10 tonone were found to consume corals 1,400 g (dry weight )m- 2 of bottombut rather fed on filamentous algae with a mean value of 50 gm- 2 in mostand detritus mixed with large Hawaiian and central Pacific reefamounts of calcareous powder. areas (Brock and Smith 1982). The

cryptobiotic resource is probablySome quantitative information not directly tapped by many fish

exists on what parrotfishes consume; species besides the parrotfishes;the most pertinent summaries are few other fishes have the dentitionfound in Al-Hussaini (1947); 11iatt and morphological adaptions neces-and Strasburg (1960); Randall sary to get into the coralline(1967); Hobson (1974); Sano, substratum. Parrotfishes do raspShimizu, and Nose (1984); Frydl and into coralline substratum as evi-Stearn (1978); and Brock (1979b). denced by tooth scars on the sub-Only the ldst two studies attempted stratum in numerous publishedto quaptitatively discern food photographs (Cloud 1959; Bakus 1967;resource partitioning among these Hobson 1974) and by the prer, nce offishes. In his study of five abundant calcium carbonate. n theHawaiian parrotfish species, Brock digestive tract.(1979b) found that Hawaiian parrot-fishes rasp algae from coralline Algae are the primary foodsubstrata, but in doing so. also resource of parrotfishes. In theconsume some animal tissue. Col- Caribbean at least 31 genera oflectively among the five species, algae are consumed along with two6 percent of the identifiable seagrass species by 10 species ofremains were animal and 18 percent par'otfishes (Randall 1967). Algaewere algal in origin; however, cal- comprise 84.7 percent and seagrassesci Lim carbonate compr i sed over make up 14.5 percent of the volume

8

of material ingested; important It is difficult , .e ta atealgal genera include Acanthophora, scarid species by d-f~eri .bces inAcrochaetium, Amphiroa, Anacystis, food consumed becarse These ishesBryothamnion, Calothrix, often feed toe, in mixed srhoolsCentroceras, Ceramium, Cladophora, over the samz substrL, ., , aid presum-Coelothrix, Corallina, Dictyopteris, ably on the same benchic resources.Dictyota, Enteromorpha, Gelidium, Frydl and Stearn (t9 78) studied sixHalimeda, Herposiphonia, Jania, sympatric Caribbean scarid speciesLaurencia, Lithothamnion, and noted some differences in feed-Lomentaria, Lyngbya, flicrocoleus, ing behavior of the species observedOscillatoria, Polysiphoiiia, in the field were reflected in theRhizoclonium, Spermothainmion, gut contents. Differences were mostSphacelaria, Spyridia, Ulva, Vidalia obvious with species that fed overand unidentified diatoms (Randall sand substrata having a greater1967). Many of these same genera proportion of benthic foraminiferahave been found in central Pacific in the stomach contents than theparrotfish stomach contents fBrock single species (Scarus viride) that1979b). Important microphytic algal foraged on hard coralline substratagenera consumed in iiawaiian waters which had consumed more encrustingincluded Jania, Pocokiella, Liagora, (hard substratum) foraminifera spe-ficrodictyon, Neomeris, Laurencia, cies. Similarly in Hawaii, BrockHerposiphonia, Polysiphonia and (1979b) found little trophic separa-Chondria (Brock 1979b). Part of the tion amongst five parrotfish spe-cryptobiota consumed by parrotfishes cies. The most obvious differencesincludes the boring algae, were related to dentition. GenericOstreobium spp. Algal consumption separation of Calotomus from Scarusrates by Hawaiian parrotfish (as is based partially on differences inexperimentally measured by dentition (Schultz 1958); Calotonuschlorophyll-a reduction) are in a has free, imbricate, incisor-likerange of 4.9 to 9 ug chlorophyll-a teeth whereas in Scarus the teethper gram (wet weight) of parrotfish are fully coalesced into a parrot-per day (Brock 1979b). like beak. The dentition and jaw

structure of Calotomus sandvicensisLobel and Ogden (1981) experimen- is not as heavy as that of Scarus

tally found a preference hierarchy perspicillatus, S. sordidus, orof algal species consumed for the S. taeniurus. Differences in denti-Caribbean parrotfish Sparisoma tion suggest differences in food andradians. In the laboratory fish fed feeding strategy. Calotomnusdiets of single plants, a mixed sandvicensis was found to have theplant diet, and starved controls most divergent of diets of the spe-showed a differential survival whikh cies examined (the least calciumparalleled the preference hierarchy carbonate by volume and the greatestwith the consumption of the most percentage of identifiable algae andpreferred plants leading to longest animal material). A fifth species,survival. In the field, S. radians Scarus dubius, has the typical fusedwas found to deliberately feed on a beak of Scarus, however the teethvariety of algae which did not and jaw structure arc less massivedirectly relate to the preference relative to S. perspicillatus.rank established in the laboratory; S. taeniurus., and S. sordIdus.in the natural setting, the consump- lhese differences were alsotion of a variety of plants presum- reflected in the diet; Scarus dubiusably served to maintain a balanced Look in more identifiable plantdiet. material and less calcium carbonate

than the other Scarus species. Thedata suggested that Scarus dubius

9

and Calotomus sandvicensis feed on m-' of planar reef surface) thissimilar materials which are probably translated into 168 bites fish 'if"more restricted to the surface of hr Ithe coral line rock (more p1 ant mate-rial and less cal ci um carbonate) Hawaiian parrotfishes spend aboutthan the food materi,;Js consumed by 60 percent of the (lay engaged inScarus perspicillatus, S. sordidus, feeding (Brock 1979b). Ogden andand S. taeniurus. The greater pro- Buckman (1973) note that the Carib-portion of calcium carbonate slurry bean species Scarus croicensispresent in the gut contents of the spends about 8 hours, or 62 percent,latter species suggested that they of the day foraging. Similarly,utilize tile cryptofaunal-Ostreobium other Caribbean scarids spend anlayer to a greater extent than do estimated 75 to 80 percent of theother fishes. The lack of separa- day foraging. Juveniles pass foodtion within this latter jroup sug- materials within I to 2 hr followinggests that (a) differential ingestion, middle-sized fishutilization of fcod materials by (250-500 g wet weight) retain fooothese species is very subtle, or materials for 3 to 5 hr, and larger(b) that the food resources are suf- fish (1 kg or more) turn over theirficiently great that there is no intestinal contents only once a daycompetitive interactioi and hence no (Bardach 1961). In contrast, Smithecological separation by way of food and Paulson (1974) estimate that(Brock 1979b). 1-kg parrotfish will turn over

their food materials twice a day andParrotfish are durnally active small parrotfish (i.e., 12 cm SL

(Bardach 1959; Randall 1967). Anal- Scarus croicensis) have intestinalysis of scarid stomachs col lected turnover rates of up to 15 times alate at nighL on Caribbean reefs day (Ogden 1977). Lobel and Ogdenshow them to be empty; feeding corn- (1981) note that satiation occursmences at sunri se and continues dfter 15 Miin of unrestrained feedingthrough the day until sunset (Frydl in Sparisoma radians. Considering aand Stearn 1978). Feeding rates number of sizes, Frydl and Stearnhave been calculated for parrot- (1978) obtained a neai turnover ratefishes in some localities. In the of about eight times day '. lheseCaribbean, Frydl and Stearn (1978) data suggest that the considerablefound that scarids spend 80 percent time spent feeding along with theof their time feeding on surfaces short retention time is indicativecovered by filamentous algae, about of little energy derived on a per20 percent on sand, and less than unit time basis from the coralline1 percent on othev (live coral , substratum food resources. Iheresponge, etc.) surfa(es. W i 1e feed - ure, however, few other fisies thating, Sparisoma viride ard Scarus can use the cora I Iine substratum andaurofrenatum make about 10 bites cryptobiota directly as a foodmin ' on the substratum, while S. resource.taeniopterus, S. croicensis, andS. vetula feed in bursts of about Growt h30 bites min I separated by short(20-sec) intervals for repositionig Randall (1962) reported growth1 17- I ..r Q n-ry 7 ra tes fo r s e ve ral Ca r ibbean icar idB3rock (1979b) using polyvinyl chlo species from mark and recaptureride (PVC) panels and counting fod studies, rates varied from 3.5 toing scars, found sc ar ids (four 20 mm p er month. Both Randallcommon species) to foed at a rate of (196?) and Reeson (1983) prov ide1.2 btes - 'day . At normail leg th-wemlghit data for some Car- 6-Ilawailan field deun'itme, (0.8 f ,h hI bean parrot fIshes. Growt h in the

10

species that have been studied is hundred meters while feedingisometric (Reeson 1983). (Bardach 1958; Randall 1961; Winn,

Marshall, and lHazlett 1964).Although home ranges have been iden-

ECOLOGICAL ROLE tified for some scarids, consider-able variation in local dispersion

Behavior within a species may exist (Coltonand Alevizon 1981; Alevizon and

Parrotfishes, like other herbivo- Landmeir 1984). Buckmian and Ogdenrous species, are diurnally active. (1973) and Ogden and Buckman (1973)At dusk they seek shelter to rest have noted three behavioral patternsand commence activity at about the in Scarus cro censis: (1) bothtime of sunrise (Hobson 1972, 1973; striped-phase and terminal-phaseCollette and Talbot 1972; Starck and fishes may repeatedly be found inDavis 1966). A number of parrotfish the same area of reef and use thesespecies (primarily Scarus) produce areas for feeding, (2) striped-phasemucous envelopes while "asleep" on and terminal-phase fish may activelythe reef. Mucous envelopes have defend a territory which contrastsanterior and posterior openings and to (3) large foraging groups ofare produced by opercular glands these fishes that are seen to move(Byrne 1970). These envelopes form and feed over the reef all day.a cocoon around the body of the fishand are believed to reduce predation Scarids will school both monospe-by nocturnal predators such as cifically, with other parrotfishmuraenid eels (Winn and Bardach species, or in mixed aggregations1960). Rosenblatt and llobson (1969) (Winn and Bardach 1960; Starck andnote that only small individuals of Davis 1966). There may be certainScarus in the eastern Pacific regu- selective advantages to the forma-larly produce the mucous envelope tion of these groups: they maywhich supports the predation hypoth- serve an antipredator behavioralesis (e.g., small individuals are function (Hobson 1969; Ehrlich andprobably subjected to greater preda- Ehrlich 1973) or allow access totion than are larger fish). otherwise unavailable food resources

(Vine 1974; Alevizon 1976). In theScarids undertake daily migra- latter case, schools of herbivorous

tions between their diurnal feeding fishes are able to forage on benthicareas and nocturnal resting sites. algal resources in actively defendedAs dusk approaches many tend to pomacentrid territories by largeaggregate in shallow water, then numbers of grazing fishes overwhelm-move to resting sites in deeper ing the defending pomacentrid.areas. Ogden and Buckman (1973)were able to identify specific Sediment Productionroutes that Scarus croicensis uti-lize in their daily movements. Some As noted above, it has been wellScarus species apparently use sun established that parrotfishes ingestnavigation to return to spec fic considerable amounts of carbonateresting sites (Winn, Marshall, and material in their feeding. Emeryllazlett 1964). It has not been (1956) examined two specimens ofestabl i shed whet her )arr ot f i shes-, Tartjs Itrs) 7c 1 latus from Jnhnstonutilize the same sleeping site each Atoll and found that about 90 per-night (Reeson 1983). In the Carib- cont (by volume) of the digestivebean some scarid species appear to tract materials were composed ofbe associated with the same area or calciurn carbonate. Cloud (1959)"home reef" for variable periods of stated that parrotfishes contrioutetime but will traverse several between 4.25 to 6.18 metric tons of

11

calcium carbonate sediment per hect- urchins. These species are allare of reef per year. Similarly potential competitors with scaridsBardach (1961) found the total non- for available benthic algalnutritive component of grazing and resources but few studies haverasping fish gut contents to be 2 to attempted to define the potential4 percent of their body weight in for interaction. It is usuallythe Caribbean. He estimated that difficult to separate the effects ofthese reef raspers produce 2,300 kg sea urchins from those of fishesof calcium carbonate sediment per (Ogden and Lobel 1978); as urchinshectare per year. Similarly, the are more easily manipulated theyCaribbean species, Sparisoma viride, have received more attention fromproduces 2,088 kg of calcium carbon- field ecologists (Ogden 1976).ate sediment per hectare per year(Gygi 1975). Ogden (1977) concluded Ogden, Brown, and Salesky (1973)that on the Caribbean ceast of Pan- found an increase in populationama Scarus croicensis produces sizes of juvenile parrotfishes and4,900 kg of sediment ha'yr-1. Frydl surgeonfishes following the removaland Stearn (1978) found actual sedi- of all sea urchins (Diademament production by Caribbean scarids antillarium) from a St. Croix patchto be less, ranging from 400 to reef. lay and Taylor (1985) noted1,700 kg ha-'yr-; these fishes pri- that the removal of sea urchins onmarily turn over existing sediment. sections of Caribbean reefs resultedData presented by Frydl and Stearn in significant local increases in(1978) show sediment turnover to herbivorous fishes including parrot-ranpe from 3,400 to 5,900 kg fishes. The natural die-off ofha- yr- . Nevertheless, the inwl.ct Diadema in the Caribbean (Lessios,of the production and redistribution Robertson, and Cubit 1984) led toof all this material on coral reefs significant increases in the popula-is large and must have an impact on tion sizes of parrotfishes and sur-the surrounding communities in which geonfishes within 9 months of theit occurs. event (Carpenter 1985, 1986; Ogden

and Carpenter 1987). These dataInteraction With Other Herbivorous suggest that competitive interac-Species tions do occur among sea urchins,

parrotfishes, and surgeonfishes.Herbivorous fishes are a common

element of most coral reef fish In a field manipulation, Brock*communities, comprising 15 to 25 introduced sea urchins to an iso-percent of the biomass and species lated Hawaiian patch reef that pre-diversity (Ogden and Lobel 1978; viously had lacked urchins but hadBrock, Lewis, and Wass 1979). On maintained a stable assemblage ofcentral Pacific reefs fishes in the herbivorous fishes. Major shifts infamilies Kyphosidae, Acanthuridae, the benthic community of the experi-Pomacentridae, and Pomacanthidae all mental reef occurred: macroalgaehave species that are primarily disappeared and within a year, coralherbivorous. The parrotfishes are coverage had significantlyoften the most abundant family increased. Monitoring the fish(Randall 1963b; Bakus 1967; Goldman populations on the experimental andand Talbot 1975; Jones and Chase nearby control reefs showed a1975). The other major herbivorous decline in the abundance of fishesgroup on coral reefs iz the sea on both reefs but there were no

* Brock, R. E. (in preparation) Sea urchins and coral reef fish communitystructure. 26 pp.

12

significant differences. The lack These fleshy algal mats also retardof significant change in the herbiv- the growth of more herbivore-toler-orous fish populations between the ant coralline algal species whichtwo reefs (experimental and control) cement the substratum (John andsuggests that the benthic community Poole 1973; Vine 1974). Birkelandon the manipulated reef accommodated (1977) demonstrated that herbivorousthe increased grazing pressure (her- fishes enhance the survival of coralbivore biomass 27 times greater on recruits on settlement plates in thethe experimental reef) through an Caribbean.increased rate of primary produc-tion. These "algal turfs" result Experimentally, grazing parrot-from high grazing pressure and may fishes have been shown to have abe three to five times more produc- tremendous impact on the structuretive than high biomass algal commu- of benthic cohmmunities. Brocknities that previously existed there (1979a) has shown that parrotfishes(Carpenter 1986). Thus, in some in densities of 0.6 to 1.5 individ-situations, benthic algal com- uals per m2 or 9 to 17 g wet weightmunities are able to respond to a of fish per m2 of feeding surfacewide range of grazing pressures, were found to have an optimum effectrapidly accommodating and supporting resulting in greatest benthic spe-fluctuations in the abundance and cies richness and biomass on two-diversity of herbivorous forms and dimensional surfaces. The presencethereby reducing competitive of refuges (three-dimensional habi-interactions. tats), however, had a greater impact

on benthic community structure (num-Role In Structuring Benthic ber of species and biomass) than didCommunities just the number of parrotfishes in

such an experimental system. CoralQualitative observations suggest recruitment was enhanced by the

that parrotfishes are important to presence of refuges and, like coral--the observed community structure of line algae, was more successfulsessile benthic forms through feed- under increased parrotfish grazinging activities (Bakus 1966, 1969, pressure. The optimum densities of1972). Indiscriminant raspinq of scarids in the experiments werethe substratum may serve to reduce found to relate well to observedbenthic species dominance, creating field densities in Hawaii. Theseptchiness leading to an increased experimental data suggest thatlocal diversity in these communi- scarids, much like some sea urchinties. Casing experiments have shown species, ma, play an important rolethat the standing crop of digae is in benthic community development andinversely related to the number of st'ucture through their feedingherbivorous Fish present (Stephenson activities. Furthermore, theseand Searles 1960; Randall 1961; results lend support to the fieldEarle 1I72). Territorial heroivo- observation that exposed benthicrous species (e.g., pomacentrids) invertebrate species other thanmay, by defending a territory, allow corals are rare on tropical Pacifica greater standing crop of fleshy reef flats (Bakus 1966) and thatalgae to develop within these terri- grazing parrotfish may be partiallytcries than is present in other responsible for this (Bakus 1964).areas exposed to herbivorous fishes.This thicker algal mat hinders coralgrowth and developmenc (Kaufman ENVIRONMENTAL REQUIREMENTS1977; Potts 1977) as well as thesettlement and growth of other Some reef fish species are spe-invertebrate species (Vine 1974). cific in their habitdt requirements.

13

Thus a small change in a coral reef often travel with these schools.community due to an environmental Adults of all Hawaiian Scarus spe-stress may result in the loss of cies may form small, mixed aggrega-certain fish and invertebrate spe- tions but adult terminal males arecies. In many instances, human- frequently solitary preferring habi-induced environmental perturbations tats seaward of the fringing reef.in Hawaiian reef systems has not ledto the local disappearance of par-rotfishes. Indeed, experimental FISHERYremoval of all fishes (includingparrotfishes) from an isolated patch Parrotfishes are important toreef led to a rapid recolonization many artisarial fisheries. In theby parrotfishes in large numbers Caribbean they are taken in traps(Brock, Lewis, and Wass 1979). Such (Reeson 1983); in the Pacificsuccessfuil recolonization by parrot- Islands they are usually captured byfishes m;.y be related to The proba- net and spear (Johannes 1981a). Onble wide patterns of movement of some Pacific Islands, fishermen takeboth juveniles and adults on Hawai- advantage of the spawning aggrega-ian reefs. However, extreme fishing tions of parrotfishes that formactivity, changes in the substratum seaward of the reef at specificresulting in the loss of appropriate times to make their catch (Johannesfood resources or the reduction of 1981a). Despite the frequentavailable cover may cause local loss appearance of parrotfishes inof parrotfishes. At present, there catches, little is known of theirare no hard data to substantiate and contribution to local fisheries.link environmental change to the Reported commercial catches of par-local disappearance of parrotFishes. rotfishes in Hawaii are small ffromBrock (1979b) reports that drastic 1.2 to 15.1 metric tons per annumhabitat changes (nutrient enrichment over the last 20 years) but the non-through sewage and beach improvement documented recreational catches mustby sand introduction) may have be large. Hawaiian parrotfishes areres: ted in the local reduction and sought after and are particularlyscarcity of parrotfish at two Hawai- susceptible to spearfishing methodsian localities. when asleep in the coral at night.

Reeson (1983) presents length-In general, parrotfishes are frequency distributions of parrot-

found on coral reefs where the water fishes from Caribbean reefs (bothis relatively clean, has good circu- unexploited and subject2d tolation characteristics, and is well- fishing).oxygenated. In the coral reefenvirorment, parrotfishes appear tofavor areas that have a considerable RECOMMENDATIONS FOR CONSERVATIONamount of open hard substratum; thisand the2 presence of appropriate Experimentally scarids have beenshelter is a prerequisite to their shown to be important to the mainte-success. Some parrotfish species nance of coral reef systems throughshow specific habitat preferences their feeding activities (Brockwith size where juveniles may be 1979a). It has been suggested thatspatially separated from adults. both parrotfishes and certain seaJuveniles ot the Hawaiian species urch-n species may be serving in aoften form mixed schools which may "keystone species" role (sensu Painerange in size from a few to more 1966) fostering the recruitmentthan 1,500 individuals. Under these success and growth of corals andcircumstances, adult Scarus sordidus coralline algae (Brock 1979a; Ogdenand subadult S. persp7cillatus will and Carpenter 1987). These

14

carbonate producers are important to Western ideas. Johannes (1978,the geological structure of reefs, 1981a, 1981b, 1982) presents a num-elevating the need for conservation ber of traditional management andof these keystone species. conservation measures that have been

practiced in Oceania and apparentlyWith population and economic work well. These include strategies

growth in the tropical insular set- for reef and lagoon tenure as welltings, many coral reefs and the as limited entry. Other restric-species inhabiting them are coming tions are or were tied to religiousunder increasing pressure. Parrot- or superstitious beliefs.fishes as part of the reef faunahave likewise received increased All of these methods serve toexploitation. Methods to counter conserve resources; these managementdegradation of habitat and overfish- regimes are based on localized con-ing are limited; effective manage- trol over access, and relative to ament strategies for these systems common property regime, offer theand species are few. The manager of potential for a more rational use ofcoral reef resources is faced with the resources. Because they arenumerous biological, political, decentralized these management meth-cultural, and economic constraints ods may closely match the diffuseof a magnitude and complexity as to nature of many coral reef fisheries.render sound scientific management a Where the resources of a centralnear impossibility (Johannes 1981b). governing body are limited, a dif-These insular settings have no con- fuse management strategy may be antinental shelves and seafood stocks effective alternative (Dahl 1988).are largely confined to nearshorereefs and lagoons; thus, these areas The challenge confronting theare particularly vulnerable to over- modern resource manager is incorpo-harvesting, ration of these proven management

strategies into a format that isBecause of their dependence on politically and culturally accept-

reef resources, the people of able today. In the modern context,Oceania over a millenia of trial and marine parks and reserves may pro-error devised methods of resource vide one solution, particularly ifmanagement that, in many instances, the local general public partici-have fallen into decay due to the pates in the establishment of theseintroduction of a cash economy and areas.

15

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