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4. THE PROBLEM OF BY-CATCH IN FISHERIES4.1 Regional ReviewResearch in SE Asia since <strong>the</strong> 1995 workshophave revealed that <strong>the</strong> by-catch <strong>of</strong> cetaceansand dugongs in fisheries is even greater thanpreviously supposed, and <strong>the</strong>re is no indicationthat this problem has been addressed in ameaningful or satisfactory way anywhere in <strong>the</strong>region. Illegal and unregulated fishing by distantwatercommercial fleets is a major problem forSE Asian countries. In particular, encroachmentby Taiwanese vessels in <strong>of</strong>fshore EEZ waters<strong>of</strong> <strong>the</strong> Philippines was repeatedly noted byworkshop participants. Exclusion <strong>of</strong> such vesselsfrom one country’s territorial waters all too <strong>of</strong>tensimply displaces <strong>the</strong> problem. An example is <strong>the</strong>Taiwanese tuna driftnet fishery in <strong>the</strong> ArafuraSea. Australia banned this fishery within itsEEZ after large by-catches <strong>of</strong> dolphins had beendocumented (Harwood et al. 1984). Ra<strong>the</strong>r thanending its operations, however, this Taiwanesefishery simply relocated to international watersand is now believed to be operating in Indonesianwaters with little or no monitoring or regulation.This example demonstrates <strong>the</strong> need for a regionalapproach to by-catch reduction/mitigation.It was also noted that in some instances, incentiveprograms by government agencies have beenresponsible for over-capitalization <strong>of</strong> fishing fleets,or increasing <strong>the</strong> amount <strong>of</strong> fishing with gillnetsand o<strong>the</strong>r unselective gear. There is a need to enddirected government programs and policies thateffectively, albeit inadvertently, increase marinemammal by-catch.A factor to consider in present and futureassessments is that low by-catch rates in manyareas reflect <strong>the</strong> fact that cetacean and dugongpopulations have already been severely reduced bydirect and incidental removals. Vietnam providesone particularly stark example. There, observeddensities <strong>of</strong> marine mammals in coastal watersare very low, fishing intensity is extremely high,and skulls in whale temples bespeak a formerlydiverse and abundant local marine mammal fauna(Smith et al. 1997; Doc. 3, 14).4.2 Useful Approaches and Prioritiesfor Research4.2.1 Small cetaceansOnly a few existing cetacean by-catch reduction/mitigation efforts in SE Asia were identified:WWF-Philippines, in collaboration with localgovernment, has initiated a project to developmodifications to crab-fishing gear and/or practicesin Malampaya Sound, with <strong>the</strong> goal <strong>of</strong> reducing<strong>the</strong> by-catch <strong>of</strong> Irrawaddy dolphins, especially inmatang quatro nets.Declaration <strong>of</strong> marine reserves and o<strong>the</strong>r types<strong>of</strong> marine protected areas in Brunei and Malaysiais justified, at least in part, as a way <strong>of</strong> reducingdugong and cetacean by-catch, although protection<strong>of</strong> coral reefs and seagrass beds is likely <strong>the</strong>primary impetus for such initiatives.The participants were asked to identify and rank what<strong>the</strong>y considered to be useful generic approachesto small cetacean by-catch mitigation. A total<strong>of</strong> 18 strategies were identified, <strong>of</strong> which sevenwere considered important by more than one ortwo individuals. These seven, in descending rankorder, were:1) Targeted community education and awarenessprograms.2) Improved enforcement initiatives.<strong>Second</strong> <strong>Workshop</strong> on <strong>the</strong> Biology and Conservation <strong>of</strong> Small Cetaceans and Dugongs <strong>of</strong> SE Asia 87
3) Monitoring and assessment <strong>of</strong> by-catch andfisheries.4) Gear research.5) Promotion <strong>of</strong> alternative livelihoods.6) Identification <strong>of</strong> key areas and closure <strong>of</strong>fisheries.7) Development <strong>of</strong> laws and regulations toreduce by-catch.While it was recognized that by-catch data frominterviews are almost always seriously biaseddownward (Lien et al. 1984), <strong>the</strong> participantsacknowledged <strong>the</strong> difficulty <strong>of</strong> placing observerson small artisanal fishing vessels, and <strong>the</strong>refore<strong>of</strong> obtaining by-catch data for such fisheries anyway o<strong>the</strong>r than by interviews. However, it wasnoted that in <strong>the</strong> United States, some small-boatfisheries have been successfully observed fromone or more independent vessels that movearound on <strong>the</strong> fishing ground and monitor <strong>the</strong> netsfrom a distance as <strong>the</strong>y are being hauled. Also,in California it has proven feasible to use shorebasedobservers to obtain unbiased data on bycatchfor some nearshore fisheries (Hanan et al.1986).Data need to be collected in such a way that bycatchrates can be discriminated at least to <strong>the</strong>species level. Moreover, for by-catch rate estimatesto be meaningful in population assessment, itis necessary to have good information on stockstructure and abundance. For small populationswhere sufficient data are available, e.g., <strong>the</strong>Irrawaddy dolphins in Malampaya Sound,Philippines, it may be possible and useful tocalculate a potential biological removal (PBR)level (“mortality limit,” as it is called in Europe)and/or to conduct a population viability analysis(PVA). These kinds <strong>of</strong> calculations can informpolicy makers and resource managers as to <strong>the</strong>probable consequences <strong>of</strong> various alternativemanagement strategies.4.2.2 Dugongs<strong>Workshop</strong> participants with dugong experiencesuggested <strong>the</strong> strategies listed in Table 9 ashaving <strong>the</strong> potential to mitigate dugong bycatch.Participants from each country <strong>the</strong>nidentified <strong>the</strong> three or four measures that <strong>the</strong>yconsidered most likely to succeed in <strong>the</strong>ircountry. The results, summarized in Table 9,indicate that community-based education andmanagement was considered <strong>the</strong> most promisingstrategy for nine countries, spatial closures inkey habitats for seven countries and improvedenforcement for seven countries. Given <strong>the</strong>value <strong>of</strong> dugong products and <strong>the</strong> resultant lowprobability <strong>of</strong> dugongs being released alive inmany countries as outlined above, area closuresto high-risk fisheries (i.e., those likely to catchdugongs) are probably <strong>the</strong> most effective means<strong>of</strong> reducing dugong by-catch. However, suchclosures are especially problematical in developingcountries where <strong>the</strong>y would be regarded asinimical to food security. In addition, <strong>the</strong> effectiveenforcement <strong>of</strong> closure areas will be prohibitivelyexpensive unless <strong>the</strong>re is widespread communitysupport (hence <strong>the</strong> need for community educationprograms).4.3 Development <strong>of</strong> Draft Plan <strong>of</strong>ActionThe group discussed various potential approachesto coordinate regional action. It was agreed that<strong>the</strong> best strategy would be to formulate a planin two stages, <strong>the</strong> first phase to concentrate onraising awareness <strong>of</strong> <strong>the</strong> issue <strong>of</strong> by-catch and <strong>the</strong>second on assessment and mitigation. An initialawareness-raising phase is necessary because inmuch <strong>of</strong> SE Asia awareness <strong>of</strong> <strong>the</strong> conservation88 CMS Technical Series Publication Nº 9 - 2005
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CMS Technical Series Publication N
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Published by the U
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TABLE OF CONTENTSpage1. Preliminari
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AppendicesAppendix 1 - List <strong
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8 CMS Technical Series Publication
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10 CMS Technical Series Publication
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The cetacean species reviewed inclu
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Table 1. Major commercial Commonwea
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(2) State Legislation.In state wate
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(2) Identification of</stro
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Coastal speciesThe most frequently
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Coastal speciesThere are currently
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and Guangxi Provinces (Yang et al.
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Table 3. Records of</strong
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can be viewed as the</stron
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Workshop participa
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ioaccumulation have not yet been ex
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of fishermen who h
Page 37 and 38: are supplied to scholars and organi
Page 39 and 40: threats. Many marine mammal populat
Page 42: waters or recognize important inter
Page 47 and 48: James Cook University (Queensland,
Page 49 and 50: the last ten years
Page 51 and 52: proactive in engaging more staff an
Page 53 and 54: of SE Asia. Two sp
Page 55 and 56: San Francisco (Negros Oriental); Li
Page 57 and 58: Legal status and present management
Page 59 and 60: within 15 kilometers from t
Page 61 and 62: US, has actively participated in ce
Page 63 and 64: the project was su
Page 65 and 66: Recently, the camp
Page 67 and 68: Mekong River downstream of<
Page 69 and 70: porpoises in tropical waters <stron
Page 71 and 72: species in the Ind
Page 73 and 74: Population/stock structureNo new in
Page 75 and 76: Needs for additional researchStock
Page 77 and 78: waters of SE Asia,
Page 79 and 80: caused mortality is certainly large
Page 81 and 82: Needs for additional researchProper
Page 83 and 84: from SE Asia, it is known to occur
Page 85 and 86: 3.1.7 AustraliaDugongs occur all al
Page 87: Table 8. Conservation objectives id
Page 91 and 92: Table 10. Outline of</stron
Page 93 and 94: The group agreed that this set <str
Page 95 and 96: 6. SUMMARY AND CONCLUSIONSThe works
Page 97 and 98: 96 CMS Technical Series Publication
Page 99 and 100: Bank, E. 1931. A popular account <s
Page 101 and 102: Dalebout, M. L., J. G. Mead, C. Sco
Page 103 and 104: Jaaman, S. A., E. Tangon, I. Isnain
Page 105 and 106: Lin, Y.-J. 1997. Mitochondrial DNA
Page 107 and 108: Smith, B.D., T. A. Jefferson, D. Ho
Page 109 and 110: Yang, W.-C. 2000. Morbillivirus inf
Page 111 and 112: CHOU Lien-SiangDepartment o
Page 113 and 114: Brian D. SMITHWildlife Conservation
Page 115 and 116: APPENDIX 3Agenda1. Preliminaries2.
Page 117 and 118: Doc. 22 Dugong conservation activit
Page 119 and 120: AreaDatesSurveyTypeEffortSpeciesNo.
Page 125 and 126: Phase ofActionPlan
Page 127 and 128: [Small cetaceans are defined to inc
Page 129 and 130: f) recognizing that by-catch in fis
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Page 133 and 134: APPENDIX 9Abstracts of</str
Page 135 and 136: The (IUCN Critically Endangered) Du
Page 137 and 138: Status of
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Cetacean Habitats in the</s
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Conservation of <s
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Summary of Current
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Indonesia’s Cetacean Migration Co
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Conservation Effort to Protect <str
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The Status of <str
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Can the Developing
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Status and Conservation of<
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Legal Hunting of C
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Indo-Pacific Bottlenose Dolphins (T
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Feasibility Study of</stron
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Songs of a Humpbac
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