Christensen, V. and D. Pauly. 2001. Coral reef and other tropicalfisheries, p. 534-538. In: J.B. Steele, S.A. Thorpe and K.K.Turekian (Eds) Encyclopedia of Ocean Sciences. Academic Press.

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that the transfer of technology, management ap-proaches, and scientific models to tropical countrieswould assist them in a way that would help to raisethe standard of living and the food supply. Many ofthese aims have been achieved, although not neces-sarily through such North/South transfer but ratherthrough local groWth of the preexisting fisheries,and through access rights granted to distant waterfleets of developed countries to operate in the watersof developing countries. These developments haveturned tropical and reef fisheries from the marginalactivities they were in the 1960s and 1970s to keyplayers in international fisheries. Catches in tropical

V. Christensen, University of British Columbia,Vancouver, BC, CanadaD. Pauly, University of British Columbia,Vancouver, BC, Canada

Copyright @ 2001 Academic Press

doi: 1 O. 1 006/rwos.2001.0450

IntroductionUntil recently studying and reporting on tropicalfisheries tended to be done in the context of devel-opment aid projects initiated with the perception

CORAL REEF AND OTHER TROPICAL FISHERIES 535

ily with effort, but stagnated after a decade andsince then they have remained at about the samelevel in spite of increasing effort. At first glance thismay be indicative of a sustainable fishery -after allthe catch level has been maintained for severaldecades. However, a closer look shows a differentand unfortunately very typical picture.

As the fishing pressure increased, the longer-livedspecies rapidly declined, many by a factor of 10 ormore within a decade. Sharks and the larger rayswere among the first to disappear because of theirlow fecundity and long life spans, while the domi-nant group (by weight) in the ecosystem changedfrom ponyfishes to squids within a decade from theonset of the trawl fisheries. The average trophiclevel of the catches, as well as of the ecosystemresources in the Gulf, has decreased steadily as fish-ing pressure mounted. Hence, catch level may bemaintained but what is being extracted is smallerand generally lower-value catches; the average fish isfinger-sized. The groupers, snappers, and most otherhigh-value species are gone, and the catches includesome 40% of 'trashfish', i.e. small species andjuveniles of larger, commercial species. The trashfishare being used to produce fish oil and meal mainlyto supply a growing aquaculture industry.

The degradation of the Gulf of Thailand ecosys-tem' as described is typical of what is happening tothe6sheries of the world because of overexploita-tion;and is indicative of a process now generallybeing c-alled 'fishing down the food web'. This termrecognizes how we change ecosystems by systemati-cally eradicating the upper trophic levels, how wefollow up by removing the more intermediate levelsto end up catching squids, shrimps, and otherorganisms low in the food web. This may be con-sidered an eco~omically interesting alternative tothe unexploited state given the high value of squidsand shrimps, but a closer examination shows that it'is a dangerous"'path, be~t with increased risk" ofunwanted structural <hang~s in the underlying eco-systems."The scientific and ptactica.l challenge lies inbalancing the harvesting so as to maintain healthyecosystems. Also, the path does not recognize thegrowing public concern for marine ecosystems-they may be largely out of sight but they are nolonger out of fuind.

~ and subtropical fisheries presently exceed those in

developed countries, as do exports from developingto developed countries -which dwarf exports in theopposite direction. In the process tropical fisherieshave become globalized to a much further extentthan other food commodities such as rice, forexample, which is overwhelmingly consumedlocally.

The experience gained in developing, managing,and studying developing country fisheries have inthe process become part of the mainstream of fishe-ries research. Some of these findings are presentedbelow to characterize trends in tropical and coralreef fisheries, which have paralleled or in some casepreceded developments in higher latitude fisheries.

Coral Reef and Tropical Fisheries

Fisheries Development

Through the first half of the last century the tropicalseas were only lightly exploited by humans, even ifcoastal areas were harvested on a small scale usingsustainable methods and often with locally basedregulation methods in place. However, during theinter-war period many colonial states tried to intro-duce more industrial fishing methods to increaseproductivity and food supply. In general, the earlyattempts were not particularly successful, an excep-tion being the introduction of trawling in the SouthChina Sea area by the Japanese in the late 1920s.

After the Second World War surplus engineSl'-atrdcrafts allowed for an expansion of effort in manyareas and the following decades saw the introduc-tion of trawling in most of the coastal shelf areas ofthe tropics. Stagnating catches and signs of overfish-ing soon followed the expansion of trawling; anearly example of this came from the Manila Bay inthe Philippines where trawling was introducedshortly after the war, and where overfishing wasapparent by the late 1950s. "

The classical, well-documented case ot how fishe-ries 'development' with the introduction of trawlingquickly leads to stagnating catches in spite of conti-nuing build-up of effort comes fr~~ the Gulf (;fThailand. Here a development project in the earlypart of the 1960s initiated a demersal trawl fisheryin hitherto unexploited parts of the Gulf.. This led toa rapid build-up of commercial fisheries in themid-1960s, and has often been hailed as a leadingexample ofa successful development project. Fortu-nately, a stratified research survey series has beenin place in the Gulf continuously since 1966documenting the ecological changes brought aboutby the fisheries. Initially, the catches increased stead-

The Ecosystem Perspective

Fisheries in temperate areas are often described inthe form of their target, e.g. herring or cod fisheries.In tropical fisheries the taxonomic diversity, untilrecently not fully mastered by fish taxonomists (butsee FishBase at www.fishbase.org), along with the

536 CORAL REEF AND OTHER TROPICAL FISHERIES

had the task of developing an ecosystem model'(Ecopath) for ~ Hawaiian reef system, was inspiredby Laevastu's approach and developed a simple ver-sion of it incorporating all important functionalgroups of the ecosystem studied. The model re-quired comparatively little information for para-meterization and its ecological book-keeping systemensured that gross errors were likely to be recog-nized, hence providing a feedback to the biologicalsampling system. In the nearly two decades since itwas first,described, the Ecopath approach has beendeveloped considerably by a growing team of scien-tists, and it has now reached a level where it is beingused for ecosystem-based fisheries management inmany countries. The approach (and the softwarethat makes it operational, freely available fromwww.ecopath.org) is easy to adapt to new areas, asillustrated by the fact that it is being used in morethan 100 countries in almost equal measures intemperate and tropical countries.

Fisheries Affect the Physical Environment

Many of traditional small-scale fisheries previouslyprevailing in the developing countries of the inter-tropical belt were benign, i.e. they did not modifythe habitat in which the resources they used wereembedded. The introduction of industrialized fishingmethods and the modernization of local techniques

.:

both impacted local ecosystems very severely. Thustrawling in the narrow coastal shelf destroys struc-tured habitats with sponges and soft coral to anextent that was not visible in the fisheries of thehigher latitudes (where benthic habitats are alsodestroyed). Furthermore, coral reefs, which areimportant in the inter-tropical belt, are now ex-ploited by extremely destructive methods such asdynamite and cyanide fishing; the latter usually tocatch live large fish for restaurants or for the orna-mental trade, both of which support valuable exportsectors. Here again it is the visibility of the impactsthat have subsequently led in the North to reassess-ment of the physical impact of fisheries on habitat.An example of this is the growing concern abouthow trawling impacts ecosystems; for instance, howheavy beam trawls have eradicated cold-water coralreef structures.

Globalization and Poverty Jointly DestroyFisheries Resources

The bulk of the countries of the inter-tropical beltdo not have the administrative structure thai wouldmake it possible to limit entry into fisheries. Theresult is that millions of landless farmers and otherrural poor have become small-scale fishers in recent

unselective nature of the fishing gear used (e.g. lift-nets or trawls in shallow waters), result in a widelydiverse catch, often comprising hundreds of speciesin a single haul. This precludes the notion of usingsingle-species management procedures, which so farhave dominated the management of temperate fishe-ries. From the onset, management in the tropics hadto be based on the yields of aggregate of species oftarget groups (e.g. groupers), implicitly or explicitlytaking account of their biological interactions. Incontrast, in temperate waters managers have onlyrecently fully realized the consequences of the non-selective nature of the gear used, and thus theecological consequences of their impact through thefood webs.

The trend in fisheries research in recent years hasbeen toward incorporating an ecosystem perspectiveinto the assessment and management of living aqua-tic resources. This is done in recognition both of thefact that there is biological interaction among theresources ('fish eat fish') and acceptance that exploi-tation has consequences not just for the exploitedresource but for their predators, competitors, andprey as well. Of especial significance here is whatmay be termed 'charismatic' organisms, notablymarine mammals, sea birds, and turtles. As the en-vironmental movement has gained strength o~er thepast decades it is becoming increasingly clear thatthere are more players to be recognized than thehunters and gatherers. Examples are the 'dolphin-free' tuna stamp now required to export tuna tothe USA, and the turtle-excluding devices requiredfor shrimp fisheries in order to maintain exportmarkets.

Incorporating the ecosystem perspective into man-agement has been an arduous task that has kept thefisheries research community challenged for decades.The pioneers in the field were E. Ursin working inthe North Sea and T. Laevastu in the north-eastPacific back in the 1970s:Since then the major stepsin the northern temperate areas have been focusedon 'multispecies virtual population analysis'(MSVPA), based on single species assessmentmethodologies but incorporating biological inter-action. Building directly on traditional assessmentmethodologies, MSVP A has had a wide supportbase in the fisheries assessment circles of the North,but it has not been widely used, partly becauseof a heavy price tag caused by its extensive datarequirements, partly because it was designed toinclude only the commercial fish species, and partlybecause its ability to address ecosystem-levelquestions is limited.

In the tropics the development has taken a differ-ent route. A US fisheries scientist, J. Polovina, who

CORAL REEF AND OTHER TROPICAL FISHERIES 537

~decades -the fisheries being the last resort for liveli-hood. These fishers have no tradition of restrainedand community control of effort as they start tocompete with more established fishers. Their lack ofaccess to capital forces them to use che~p and often,unfortunately, destructive methods -most notablyexplosives and poisons (cyanide or insecticides).

Growing populations with a need for cheap fishprovide an outlet for the low quality productsthat emerge from these activities, while a largelyinsatiable world market (notably Western Europe,USA, Japan, and China) absorbs the high qualityproducts, especially expensive invertebrates such asshrimps and sea urchins. This massive uncontrolledinflow of effort leads to what has been called'Malthusian overfishing', wherein extreme povertyreduces the cost of labor (usually a limiting factor infisheries) to virtually nothing; thus making fishing'profitable' even when productivity is very low.Adult fishers are often seen operating over an entireday to land only one pound of small fish per person.In such cases poverty and other nonfishers in thefamily subsidize the fishery.

Other subsidies impacting small-scale fisheriesand leading to gross overexploitation are providedby development banks that continue to encourageincreasing fishing effort, and the access rights thatare negotiated by powerful developed countries foroperating distant water fleets in the tropics, e.g. fortrawling off west Africa by EU vessels or tuna fish-ing in the Indian and Pacific Oceans. Such develop-ments, which have contributed to an enormousexcess capacity in the developed world, have alsocontributed to making the subsidy issue more visiblein developing countries, where attempts to addressthese problems have so far been stymied by ship-building and other powerful lobbies. There is, now-ever, a growing realization of the need to reduce theovercapitalization, as perhaps best exemplified bythe growing reluctance of development agencies tofund 'fisheries development' projects due to the rec-ognized high failure rate of such projects.

increase the yield for fishers. Such marine protectionimplies permanent closure of a significant part of anarea traditionally exploited by fisheries, 40% in thecase of the island first studied by the pioneeringteam of Dr Angel Alcala in the Central Philippines.These closures allow the growth of animals, in thiscase especially groupers and snappers, which wouldotherwise be caught as juveniles. Their increasedbiomass and the high percentage of adults withinthe MPA lead to migration from the MPAs to thesurrounding waters, and hence to increased catchesin the surrounding areas, and as has been demon-strated, to larger overall catch.

As widely noted, MPAs are not a panacea;notably they require that fishing outside the MP Asmust be regulated. Even more importantly the com-munities whose fishing grounds have been impactedby an MP A must accept the gamble that the MP Arepresents, and must indeed be the advocates andprotectors of the MP A. This implies that they haveaccepted, through fruitful interaction with scientistsor other communities that are patrons of an MP A,that th~ir fishing impacts the resource, somethingstill hotly denied by the less enlightened part of thefishing community in many countries. Further, thecommunities must be self-organized so that they canprevent defection, i.e. fishing within the MP As forthe resources that rapidly build up as the fishingpressure is released. Third, for the MP A to be set inplace, the central government for the country inquestion must have relinquished enough power tothe communities for them to be in a positioq\to takepertinent decisions and see them implemented.Finally, for the MPA approach to work fishingcommunities must have accepted the notion thatthe immediate gains from exploiting a resourcemust be put in a longer-term context. Essentiallythe community must take a conservation-orientedstandpoint, i.e. it must overcome the hugechasm which until now has separated fisheries fromconservation.

Demanding as these requirements may seem, theyhave been met in many parts of the Philippines, theCaribbean, and other parts of the world -includingNew Zealand, a developed country. Given the diffi-culties in implementing other forms of effort reduc-tion measures and the very destructive trends in theareas where MP As are not implemented it is likelythat the trend toward using MP As as an integralpart of sustainable fisheries management will con-tinue. Indicative of this trend is the fact that in hislast year of office US President Clinton signed anexecutive order calling for 'protection of existingMP As and the establishment of new MP As, asappropriate. '

Marine Protected Areas Are Partof the Solution

While the foregoing presented a number of prob-lems, which appeared or became visible first in theinter-tropical belt and only later were seen as globalproblems, this section presents elements of solutionsto the global ills, which also have appeared firstin the developing world. One of these is marineprotected areas (MPAs), first demonstrated in thePhilippines to have the potential both to allowresources to regenerate/rebuild themselves and to

CORAL REEF FISHES538

.

See also

Ecosystem Effects of Fishing. Fisheries: Multi-species Dynamics. Fishery Management. FishingMethods and Fishing Fleets. Marine FisheryResources, Global State of. Network Analysis ofFood Webs.

Further Reading

Alcala AC (1988) Effects of marine reserves on coral fishabundance and yields of Philippine coral reefs. AmbioXVII: 194-199.

Christensen V (1996) Managing fisheries involving toppredator and prey species components. Reviews in FishBiology and Fisheries 6:417-442.

Christensen V and Pauly D (eds) (1993) Trophic Modelsof Aquatic Ecosystems. ICLARM Conference Proceed-ings 26. Manila: ICLARM.

Hilborn R and Walters CJ (\992) Quantitative Fisheries'Stock Assessment, ChoiceS, Dynamics and Uncertainty.New York: Chapman and Hall.

Longhurst A and Pauly DC(1987) Ecology of TroPicalOceans. San Diego: Academic Press.

Munro JL (ed.) (1983) Caribbean Coral Reef FisheryResources, ICLARM Study Review 7. Manila: ICLARM.

Munro JL and Munro PE (eds) (1994) The Managementof Coral Reef Resource Systems. ICLARM ConferenceProceedings 44. Manila: ICLARM Studies and Reviews.

Pauly D (1979) Theory and Management of TropicalMultispecies Stocks. ICLARM Study Review 1. Ma-nila: ICLARM Studies and Reviews.

Pauly D, Christensen V, Dalsgaard A, Froese RandTorres J (1998) Fishing down marine food webs.Science 279: 860-863.

Polunin NVC and Roberts CM (eds) (1996) Reef Fishe-ries. London: Chapman and Hall

Salina C (1998) Song for the Blue Ocean. New York:H Holt & Co.

M. A. Hixon, Oregon State University, Corvallis,OR, USA

Copyright @ 2001 Academic Press

doi:10.1006/rwos.2001.0015

those of corals, which provide shelter and harborprey. There is a high degree of endemism in reeffishes, especially on more isolated reefs, and manyspecies (about 9%) have highly restricted geographi-cal ranges.

The major human activities that threaten reeffishes include overfishing, especially by destructivefishing practices, and habitat destruction, includingboth local effects near human population centersand the ongoing global decline of reefs due to coralbleaching. Worldwide, about 31% of coral-reeffishes are now considered critically endangered and24% threatened. The major solution for local con-servation is 'no-take' marine protected areas, whichhave proven effective in replenishing depleted popu-lations.

Fisheries

Where unexploited by humans, coral-reef fishestypically exhibit high standing stocks, the maximumbeing about 240tkm-2 (about 24tCkm-1. Highstanding crops reflect the high primary productivityof coral reefs, often exceeding 103 gC m -2y-I, muchof which is consumed directly or indirectly by fishes.Correspondingly, reported fishery yields have reach-ed 44tkm-2y-I, with an estimated global potentialof 6M ty-I. These fisheries provide food, bait, andlive fish for the aquarium and restaurant trades.However, the estimated maximum sustainable yieldfrom shallow areas of actively growing coral reefs is

Diversity, Distribution, andConservation

Coral-reef fishes comprise the most speciose assem-blages of vertebrates on the Earth. The variety ofshapes, sizes, colors, behavior, and ecology exhib-ited by reef fishes is amazing. Adult body sizes rangefrom gobies (Gobiidae) less than 1 cm in length totiger sharks (Carcharhinidae) reportedly over 9mlong. It has been estimated that about 30% of thesome 15000 described species of marine fishes in-habit coral reefs worldwide, and hundreds of speciescan coexist on the same reef. Taxonomically, reeffishes are dominated by about 30 families, mostlythe perciform chaetodontoids (butterflyfish andangelfish families), labroids (damselfish, wrasse,and parrotfish families), gobioids (gobies), andacanthuroids (surgeonfishes).

The latitudinal distribution of reef fishes followsthat of reef-building corals, which are usually lim-ited to shallow tropical waters bounded by the 20°Cisotherms (roughly between the latitudes of 300Nand S). The longitudinal center of diversity is theIndo-Australasian archipelago of the Indo-Pacific re-gion. Local patterns of diversity are correlated with