- 期刊
- OpenAccess
Examining on the Bycatch and Discard Catch of the Shrimp Beam Trawl Fishery in the Coastal Waters off Chiayi, Southwest Taiwan
台灣西南嘉義海域蝦拖網之混獲之分析
摘要
為解析台灣桁桿式蝦拖網之漁獲物中，上市漁獲(landed catch)和拋棄漁獲(discarded catch)之間的關係，與其魚種組成，以及拋棄回海中之漁獲物之活存率，自1996年12月到2000年12月，於嘉義布袋海域每月出海蒐集一天（兩網次）漁獲物共80網次，其中14網次並針對拋棄物之活存率進行實驗，其結果如下：所有漁獲中共有甲殼類28種，魚類107種及頭足類6種。漁獲物經選別分成上市與拋棄漁獲後，綜合所有漁獲物，不管以重量或尾數計算均以主要目標漁獲上市蝦類佔最多數，分別為43.2%與43.8%，而拋棄漁獲之重量和尾數佔全體漁獲之比例分別為31.9%和52.2%，顯示本海域較世界各國之漁獲物利用率高。月別之捕獲率(kg/(haul×hour))顯示，不管上市與拋棄漁獲，以12~2月有較高之漁獲量。本海域之主要目標漁獲種類為角突彷對蝦(Parapenaeopsis cornuta)，佔上市漁獲蝦類之51.2%，其次為長角彷對蝦(P. hardwickii)佔18.9%，鬚赤對蝦(Metapenaeopsis barbata)佔14.7%，而拋棄漁獲物中，蝦類以P. hardwickii佔全體蝦類之37.5%為最高，蟹類以紅星梭子蟹(Portunus sanguinolentus)最多，魚類以大頭花桿狗母(Trachinocephalus myops)最多，頭足類以真烏賊(Sepia esculenta)最多。由主要漁獲蝦類之選別曲線得知，愈是經濟性蝦種之斜率愈陡，即其選別效果愈明顯，反之亦然。拋棄漁獲物倒回海中之活存率，綜合平均蝦類、蟹類、頭足類、魚類分別為56.3%，62%，34.8%，8.4%。
並列摘要
A total of 80 hauls from December 1996 to December 2000 including 14 hauls for survival experiment of discarded catch were conducted on the monthly basis in the coastal waters off Chiayi, southwest Taiwan to examine the catch composition, estimate the ratio of landed catch and discarded catch, and survival rate of discarded catch from shrimp beam trawlers. A total of 28, 107 and 6 species of crustaceans, finfishes and cephalopods were identified for all the catches. The catch is divided into two categories namely landed catch and discarded catch and the latter consists of 52.2% and 31.9% in number and weight, respectively. Shrimps are the dominant animals both in number (43.8%) and weight (43.2%) of the landed catch. On the other hand, fishes are dominant in weight (42.5%) and shrimps are dominant in number (51.2%) of discarded catch. Monthly catch rate (g/(haul×hour)) indicated that higher landed catch and discarded catch occur in December to next February. The major target species is Parapenaeopsis cornuta (51.2% of landed shrimps), followed by P. hardwickii (18.9%). Among the discarded catch, P. hardwickii is the dominant species of shrimps (37.5%), Portunus sanguinolentus is the dominant species of crabs, Trachinocephalus myops is the dominant species of fishes, and Sepia esculenta is the dominant cephalopods. The landing-selectivity of shrimps increased with their economical values based on the length frequency distribution of dominant species on landed catch and a logistic curve was fitted. No significantly temporal variations on length were found for discarded catch. The survival rates of discarded catch were estimated to be 56.3%, 62%, 34.8%, and 8.4% for shrimps, crabs, cephalopods, and fishes, respectively.