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

about 300 days per year, Wang estimated thatroughly 275 animals are killed incidentally andlanded at Nanfang Ao each year (note: becausemost fishermen discard by-caught cetaceans toavoid prosecution for possession, <strong>the</strong> number <strong>of</strong>carcasses landed at Nanfang Ao is necessarily lessthan <strong>the</strong> number <strong>of</strong> cetaceans actually killed). Themain species were common bottlenose (~40%),pantropical spotted (~35%) and rough-too<strong>the</strong>d(~15%) dolphins. At Shihti harbour, based on twomonths <strong>of</strong> data, Wang found at least 19 cetaceanslanded: 10 pantropical, six Risso’s and one Fraser’sdolphin, one short-finned pilot whale and onepygmy sperm whale. Based on this information,he estimated <strong>the</strong> annual cetacean by-catch bydrifnets at this port to be 475 to 570 (9.5 cetaceansper month*10 months*5 vessels). During aninterview with one Chengkung driftnetter in 2000,Wang was told that 16 or 17 cetaceans had beenkilled incidentally by this man’s drift-net vessel in 20days <strong>of</strong> fishing over a 1.5 month period. Assumingthat this fisherman was representative <strong>of</strong> o<strong>the</strong>rs atChenkung, Wang estimated, <strong>the</strong> incidental catchrate to be 10.7 cetaceans per month per boat(fairly similar to <strong>the</strong> catch rate estimated for Shihtiharbour). Using <strong>the</strong> rates determined for Shih-tiharbour (9.5 cetaceans per vessel per month) andCheng-kung (10.7 per month), Wang estimated<strong>the</strong> annual catch at Hualien harbour to be 950 to2,130 cetaceans, assuming a 10-12 month driftnetfishing period and 10-20 driftnet vessels operatingfrom this harbour. In Chengkung harbour,<strong>the</strong>re is a fleet <strong>of</strong> about 200-300 large mesh,drifting gillnet vessels. The extrapolated annualcetacean by-catch would <strong>the</strong>n be 25,680 to 38,520(10.7*12month*200-300 vessels). Wang reportedhis own earlier “guesstimate” <strong>of</strong> 5,000 to 10,000cetaceans per year for <strong>the</strong> entire east coast totwo Chengkung fishermen. These two fishermeninsisted <strong>the</strong> actual number was higher. Speciesthat have been recorded as by-catch at Chengkungharbour include Risso’s, pantropical and Fraser’sdolphins and short-finned, pygmy sperm, Cuvier’sbeaked and Blaineville’s beaked whales.By combining <strong>the</strong> estimated incidental catches from<strong>the</strong>se four harbors <strong>of</strong> <strong>the</strong> east coast (Nanfang Ao,Hualien, Shihti and Chengkung), Wang estimated<strong>the</strong> total number <strong>of</strong> cetaceans incidentally killedannually by fisheries to be between 27,000 and41,000 in <strong>the</strong> eastern waters <strong>of</strong> Taiwan (details<strong>of</strong> <strong>the</strong> driftnet fisheries and calculations werepresented in Doc. 6).Wang emphasized and <strong>the</strong> group agreed that while<strong>the</strong>se various estimates must be regarded as highlyprovisional because <strong>of</strong> <strong>the</strong> many assumptionsinvolved and <strong>the</strong> relatively small sample sizesfor <strong>the</strong> observations, <strong>the</strong>y are indicative <strong>of</strong> largescalemortality and suggest that <strong>the</strong>re should besome urgency in collecting and analyzing fur<strong>the</strong>rdata on catch and by-catch in eastern Taiwanesecoastal waters.In <strong>the</strong> Taiwan Strait (western Taiwan), fishermenwho use drifting gillnets, sink gillnets and trammelnets are plentiful. The number <strong>of</strong> cetaceans killedeach year seems to be less than in easternwaters. However, <strong>the</strong> impact <strong>of</strong> fisheries on <strong>the</strong>cetaceans <strong>of</strong> <strong>the</strong> west coast may be greater due toalready severely reduced numbers <strong>of</strong> <strong>the</strong>se coastalspecies. The species that have been recordedkilled incidentally by fisheries in <strong>the</strong> Taiwan Straitinclude bottlenose dolphins (both species) andfinless porpoises. Wang also reported that a fewfisheries may also catch cetaceans incidentallyin sou<strong>the</strong>rn waters. Nothing is known aboutcetaceans and <strong>the</strong>ir interactions with fisheries innor<strong>the</strong>rn Taiwan, where large numbers <strong>of</strong> vesselsoperate.Chou reported <strong>the</strong> results <strong>of</strong> a questionnaire survey<strong>of</strong> fishermen from <strong>the</strong> (Penghu Islands (n=146) anda portion <strong>of</strong> <strong>the</strong> east coast (Hualien and Taitungcounties; n=95) during 1999-2001. The proportion<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 33