Report of the Second Workshop on The Biology and Conservation of ...

Needs for additional researchThere is a need to study local coastal populations<strong>of</strong> this species wherever it occurs in SE Asia. Boatsurveys are urgently needed. The populationsmust be assessed, and effective conservation plansmust be implemented, before <strong>the</strong> populationsdecline to critical levels. To date, such assessmentand conservation has taken place only in HongKong, and to a lesser extent in Xiamen. Catchesto stock oceanaria should be accurately monitoredand reported. Estimates <strong>of</strong> incidental mortality andabundance are particularly needed <strong>of</strong>f <strong>the</strong> westcoast <strong>of</strong> Taiwan, in <strong>the</strong> Gulf <strong>of</strong> Tonkin nor<strong>the</strong>rnVietnam, and in <strong>the</strong> Gulf <strong>of</strong> Thailand. The ecologicaloverlap with fisheries should also be investigated,especially in <strong>the</strong> Gulf <strong>of</strong> Thailand.2.2.4 Grampus griseusDistributionWang and Chou reported that Risso’s dolphinis <strong>the</strong> most commonly encountered species <strong>of</strong>fHualien on <strong>the</strong> sou<strong>the</strong>astern coast <strong>of</strong> Taiwan. It isalso fairly common in <strong>the</strong> Bohol and Tañon Straits,Philippines, according to Dolar.Population/stock structureNo new information.Habitat statusNo new information.Directed catchesWang reported that Risso’s dolphins are harpoonedin Japan and Taiwan. There are also directed takes<strong>of</strong>f Palawan, Philippines, and <strong>of</strong>f Lamalera and Solor,Indonesia (Rudolph and Smeenk 2002). Stocks inSE Asia may be affected by catches in Japanesewaters.By-catchesThere are recent records <strong>of</strong> by-catch in gillnets ando<strong>the</strong>r types <strong>of</strong> nets in China (Doc. 9), and in largemeshdrift gillnets in Taiwan (Doc. 6). By-catchesalso occur in purse seines and driftnets in <strong>the</strong>Philippines (Doc. 19, 28).Needs for additional researchPopulation studies, based on photo-identification,should be pursued for this species, which is wellsuitedto this research technique. Some assessment<strong>of</strong> <strong>the</strong> effects <strong>of</strong> by-catch in large-mesh driftnetfisheries is also needed, particularly for deepcoastal areas <strong>of</strong>f Taiwan and o<strong>the</strong>r regions whereRisso’s dolphins and driftnet fisheries co-occur.2.2.5 Tursiops truncatusPopulation statusChou reported that some photo-identification workhad been conducted in Taiwan waters, and thatabout 300 individual Risso’s dolphins had beenidentified, thus providing a minimum estimate <strong>of</strong>population size (Kou 2002a). Dolar (1999a) producedan abundance estimate for <strong>the</strong> Sulu Sea <strong>of</strong> 941(CV=40%). There are also minimum abundanceestimates for southwestern Taiwan <strong>of</strong> 153 dolphins(CV=77%) (Huang 1996), and nor<strong>the</strong>astern Taiwan<strong>of</strong> 218 individuals (CV=29%) (Chen 2001).DistributionThere are no confirmed records <strong>of</strong> commonbottlenose dolphins in <strong>the</strong> SE Asian portion <strong>of</strong>Australian waters—all known bottlenose dolphinsrecords <strong>the</strong>re are <strong>of</strong> T. aduncus. However, Marshcautioned that <strong>the</strong> cetaceans in this area arepoorly studied. The Sulu Sea driftnet catches in<strong>the</strong> Philippines have been confirmed to be T.truncatus, based on genetics. Wang stated thatcommon bottlenose dolphins occur in both coastaland deepwater, <strong>of</strong>fshore areas <strong>of</strong>f Taiwan. The onlyreport <strong>of</strong> common bottlenose dolphins in Malaysiais from <strong>the</strong> Spratley Islands (Doc. 10).<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 71