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研究報告

更新日期: 2015-02-09
點閱數: 563

大型軟骨魚類之調查研究

年度 2014
計劃名稱 大型軟骨魚類之調查研究
中文摘要 本年度定置網共誤捕鯨鯊38尾,其他目擊的有3尾,標識放流19尾。在41尾鯨鯊裡面,宜蘭有5尾(12.2%),花蓮10尾(24.4%),台東18尾(43.9%),屏東1尾(2.4%),澎湖4尾(9.8%),竹苗3尾(7.3%);整個東部地區有33尾(80.5%),西部則有8尾(19.5%),換算成每組定置網的年平均單位努力漁獲量來看,東部為0.78(尾/組/年),西部為0.76(尾/組/年)。從整體的性別結構分析顯示,雄魚較多於雌魚。今年度鯨鯊的平均體長及體長中位數,不論雌雄都比去年低,從年齡組成顯示來游至台灣附近水域的鯨鯊多是6~9歲的未成熟個體。 本研究2013年所標識衛星籤的2尾個體,至今年仍有接受到訊號。一尾為2013年10月30日於澎湖被捕獲的未成熟雌魚,全長6.7 m,被放流後南游至菲律賓西部沿近海域停留多日,接著西移至南海,最後到達泰國灣海域,從其棲息溫度分佈情形來看,黃昏時有最高的比例會前往高溫水域,也就是接近水面位置,其他時候則除了接近水面的位置外,還會往較低水溫處(7~10 °C)移動;另一尾則是在2013年11月27日,同樣是誤入澎湖定置網的個體,為全長5.1 m的雌魚,同樣西移至南海後,到達泰國灣海域,棲息溫度在23~>30 °C間平均分佈,少數下潛至水溫10~15 °C的區域。 2014年4月29日在新竹香山標識放流的6.1 m TL雄魚,放流後往北進入東海,主要待在東海陸棚區海域,直到10月27日於日本種子島附近海域收到最後的訊號,棲息溫度有較高的比例在27~30 °C的水域,少數潛水到較低溫(10~15 °C)區域。今年10月31日在澎湖鎖港所標識放流的7.5 m TL雌魚,標識之後以很快的速度南下至屏東西南部80~100公里外海,到11月14號都持續待在附近海域,棲息溫度有極高的比例在27~30 °C的水域,有少數移動到較低溫(0~3 °C)水域的行為。大白鯊於2013~2014年間共有4尾捕獲紀錄。巨口鯊全世界至今共記錄到了87尾,其中43尾來自台灣,2013~2014年間就通報了32尾,為世界之最。所有巨口鯊都是被花蓮的流刺網漁業所捕獲,捕獲的地點多集中在花蓮近海處。在花蓮外海捕獲的巨口鯊以雌魚較多,有20尾(62.5%),體長範圍250~710 cm TL,雄魚有11尾(34.4%),體長範圍363~484 cm TL,性比為0.35。 將4尾鯨鯊及5尾巨口鯊的肌肉進行穩定性同位素氮及碳的分析,發現兩種同為濾食性的鯊魚,攝食的餌料生物型態不同,棲息環境迥異,未來還需要更多樣本做進一步分析,此外,由上述結果可以知道,若要進行巨口鯊的資源管理或保育,其策略應與鯨鯊有所不同。
英文摘要 There were 38 whale sharks barged into set nets in 2014, 19 of them were tagged and released, and 3 others were also observed. In 41 individuals, there were 5 (12.2%) from Yilan, 10 (24.4%) from Hualien, 18 (43.9%) from Taitung, 1 (2.4%) from Pingtung, 4 (9.8%) from Penghu, and 3 (7.3%) from Hsinchu and Miaoli; there were 33 (80.5%) from the east, and 8 (19.5%) from the west, converted to catch per unit effort as being calculated to be 0.78 individual per set net per year in the east and 0.76 individual per set net per year, respectively. The amount of male whale sharks was significant bigger than which of female in sex structure analysis. Both the mean total length (TL) and median TL in 2014 were smaller than which in 2013, and most whale sharks which occurred in Taiwan waters were 3-9 years old immature individuals based on age structure analysis. Two SPOTs were tagged on a 6.7 m TL immature female caught in Penghu on Oct. 30 2013 and the other 5.1 m TL female also caught in Penghu on Nov. 27 2013. Their position signals were still received during 2014. The first one swam southward to the western waters off Philippines after release and remained there for many days, then moved west through the South China Sea to the Gulf of Thailand. This individual usually moved to higher temperature as near surface regions in dusk time, and sometimes moved to lower temperature (7~10 °C) regions based on time at temperature data. The second one also swam west to the South China Sea then entered into the Gulf of Thailand at last. This shark stayed in 23->30 °C waters averagely, and dived to 10-15 °C regions in few times. A 6.1 m TL male tagged and released off Hsinchu on 49 April 2014 moved north to the East China Sea, and remained in continental shelf regions until 27 Oct. when we received its last signal in Tanega Shima waters, Japan. This male shark stayed mainly in the waters where the temperatures were 27-30 °C, and sometimes migrated to lower temperature (10-15 °C) waters. Another 7.5 m TL female released in Penghu waters on 31 Oct. swam fast south to southwest waters 80-100 km far from Pingtung and stayed in that region until 14 Nov. This individual occupied mainly in 27-30 °C waters and occurred in lower temperature (0-3 °C) waters in few times. Total of 4 great white sharks were caught between 2013 and 2014. Since the megamouth shark was found and named, there were 87 individual records until now, and 43 of them were from Taiwan as top one region of the world, even 32 were reported in 2013-2014. All megamouth sharks were caught by drift gill nets in Hualien and the locations were gathered in coastal and inshore waters. There were more females as 20 individuals (62.5%) with 250-710 cm TLs, 11 males with 363-484 cm TLs were caught in Hualien waters with sex ratio (male/total) of 0.35. Muscle tissue samples from 4 whale sharks and 5 megamouth sharks were used for nitrogen and carbon stable isotope analysis. We found that although both whale and megamouth sharks were filter-feeding shark species, they fed very different types of prey and also occupied in dissimilar environmental waters. More samples are needed to be analyzed further in the future. According to results above, if the megamouth shark will be manage or protected in the future, the strategy should be different from the whale shark.There were 38 whale sharks barged into set nets in 2014, 19 of them were tagged and released, and 3 others were also observed. In 41 individuals, there were 5 (12.2%) from Yilan, 10 (24.4%) from Hualien, 18 (43.9%) from Taitung, 1 (2.4%) from Pingtung, 4 (9.8%) from Penghu, and 3 (7.3%) from Hsinchu and Miaoli; there were 33 (80.5%) from the east, and 8 (19.5%) from the west, converted to catch per unit effort as being calculated to be 0.59 individual per set net per year in the east and 0.57 individual per set net per year, respectively. The amount of male whale sharks was significant bigger than which of female in sex structure analysis. Both the mean total length (TL) and median TL in 2014 were smaller than which in 2013, and most whale sharks which occurred in Taiwan waters were 3-9 years old immature individuals based on age structure analysis.     Two SPOTs were tagged on a 6.7 m TL immature female caught in Penghu on Oct. 30 2013 and the other 5.1 m TL female also caught in Penghu on Nov. 27 2013. Their position signals were still received during 2014. The first one swam southward to the western waters off Philippines after release and remained there for many days, then moved west through the South China Sea to the Gulf of Thailand. This individual usually moved to higher temperature as near surface regions in dusk time, and sometimes moved to lower temperature (7~10 °C) regions based on time at temperature data. The second one also swam west to the South China Sea then entered into the Gulf of Thailand at last. This shark stayed in 23->30 °C waters averagely, and dived to 10-15 °C regions in few times.     A 6.1 m TL male tagged and released off Hsinchu on 49 April 2014 moved north to the East China Sea, and remained in continental shelf regions until 27 Oct. when we received its last signal in Tanega Shima waters, Japan. This male shark stayed mainly in the waters where the temperatures were 27-30 °C, and sometimes migrated to lower temperature (10-15 °C) waters. Another 7.5 m TL female released in Penghu waters on 31 Oct. swam fast south to southwest waters 80-100 km There were 38 whale sharks barged into set nets in 2014, 19 of them were tagged and released, and 3 others were also observed. In 41 individuals, there were 5 (12.2%) from Yilan, 10 (24.4%) from Hualien, 18 (43.9%) from Taitung, 1 (2.4%) from Pingtung, 4 (9.8%) from Penghu, and 3 (7.3%) from Hsinchu and Miaoli; there were 33 (80.5%) from the east, and 8 (19.5%) from the west, converted to catch per unit effort as being calculated to be 0.78 individual per set net per year in the east and 0.76 individual per set net per year, respectively. The amount of male whale sharks was significant bigger than which of female in sex structure analysis. Both the mean total length (TL) and median TL in 2014 were smaller than which in 2013, and most whale sharks which occurred in Taiwan waters were 3-9 years old immature individuals based on age structure analysis. Two SPOTs were tagged on a 6.7 m TL immature female caught in Penghu on Oct. 30 2013 and the other 5.1 m TL female also caught in Penghu on Nov. 27 2013. Their position signals were still received during 2014. The first one swam southward to the western waters off Philippines after release and remained there for many days, then moved west through the South China Sea to the Gulf of Thailand. This individual usually moved to higher temperature as near surface regions in dusk time, and sometimes moved to lower temperature (7~10 °C) regions based on time at temperature data. The second one also swam west to the South China Sea then entered into the Gulf of Thailand at last. This shark stayed in 23->30 °C waters averagely, and dived to 10-15 °C regions in few times. A 6.1 m TL male tagged and released off Hsinchu on 49 April 2014 moved north to the East China Sea, and remained in continental shelf regions until 27 Oct. when we received its last signal in Tanega Shima waters, Japan. This male shark stayed mainly in the waters where the temperatures were 27-30 °C, and sometimes migrated to lower temperature (10-15 °C) waters. Another 7.5 m TL female released in Penghu waters on 31 Oct. swam fast south to southwest waters 80-100 km far from Pingtung and stayed in that region until 14 Nov. This individual occupied mainly in 27-30 °C waters and occurred in lower temperature (0-3 °C) waters in few times. Total of 4 great white sharks were caught between 2013 and 2014. Since the megamouth shark was found and named, there were 87 individual records until now, and 43 of them were from Taiwan as top one region of the world, even 32 were reported in 2013-2014. All megamouth sharks were caught by drift gill nets in Hualien and the locations were gathered in coastal and inshore waters. There were more females as 20 individuals (62.5%) with 250-710 cm TLs, 11 males with 363-484 cm TLs were caught in Hualien waters with sex ratio (male/total) of 0.35. Muscle tissue samples from 4 whale sharks and 5 megamouth sharks were used for nitrogen and carbon stable isotope analysis. We found that although both whale and megamouth sharks were filter-feeding shark species, they fed very different types of prey and also occupied in dissimilar environmental waters. More samples are needed to be analyzed further in the future. According to results above, if the megamouth shark will be manage or protected in the future, the strategy should be different from the whale shark.far from Pingtung and stayed in that region until 14 Nov. This individual occupied mainly in 27-30 °C waters and occurred in lower temperature (0-3 °C) waters in few times.     Total of 4 great white sharks were caught between 2013 and 2014. Since the megamouth shark was found and named, there were 87 individual records until now, and 43 of them were from Taiwan as top one region of the world, even 32 were reported in 2013-2014. All megamouth sharks were caught by drift gill nets in Hualien and the locations were gathered in coastal and inshore waters. There were more females as 20 individuals (62.5%) with 250-710 cm TLs, 11 males with 363-484 cm TLs were caught in Hualien waters with sex ratio (male/total) of 0.35.     Muscle tissue samples from 4 whale sharks and 5 megamouth sharks were used for nitrogen and carbon stable isotope analysis. We found that although both whale and megamouth sharks were filter-feeding shark species, they fed very different types of prey and also occupied in dissimilar environmental waters. More samples are needed to be analyzed further in the future. According to results above, if the megamouth shark will be manage or protected in the future, the strategy should be different from the whale shark.   
計畫編號 103農科-11.2.1-漁-F3(3)