| Abstract: | 本研究蒐集2012-2015年間實際在台灣西南海域作業(北緯24度以南)之扒網漁業樣本船的漁業活動資料，以及衛星遙測海洋表面水溫(sea surface temperature ; SST)、葉綠素濃度(sea surface chlorophyll-a；SSC)、海洋表面高度(sea surface height ; SSH)、風速(Wind speed)及降雨量(Precipitation；Pr)等環境資料，利用圖層分析及主成分分析法來探究臺灣西南海域扒網漁業作業漁場之時空分布與漁海況特性。 由樣本船漁獲資料顯示，台灣西南海域扒網漁業的漁獲物種中以眼眶魚、花腹鯖、真鰺、黃鰭鮪、正鰹、大甲鰺、藍圓鰺、圓花鰹、脂眼鲱等9種魚類有較高的漁獲量，且在夏季時以正鰹及黃鰭鮪有較高的漁獲量，冬季時則以真鰺及花腹鯖有較高的漁獲量，而在春秋兩季時則以眼眶魚有較高的漁獲量。 由圖層分析的結果顯示，台灣西南海域扒網漁業的作業漁場中，有三處漁獲量較高的分布熱點，分別位於臺灣本島西南沿岸(118°~121°E、21°~23°N)、臺灣淺灘東南方(116°~118°E、21°~23°N)延伸至澎湖海域(118°~120°E、23°~24°N)，且由年間月別漁場重心之推移顯示，在 2012-2014年間月別漁場重心以南北向推移為主，但2015年則轉變為東西向之推移。 主成分分析的結果顯示，重要漁獲物種間漁獲特性相近物種為花腹鯖與真鰺、正鰹與黃鰭鮪、眼眶魚；與環境因子間關係正鰹 、黃鰭鮪與海表面水溫、海表面高度及葉綠素a濃度呈正相關，眼眶魚則與海表面水溫、海表面高度呈負相關，花腹鯖與海表面水溫、海表面高度呈正相關，真鰺與降雨量呈正相關。 綜合上述，本研究證實了西南海域扒網漁業之主要漁獲魚種與漁場有時間及空間上之變異，應與環境變動所造成的不同海況有關。
The present study aimed to explore spatial and temporal characteristics of fishing and oceanic conditions for Taiwanese-seine fisheries in the water off southwestern Taiwan. We collected fishing activity data from logbook as well as environmental data such as sea surface temperature (SST), Chlorophyll-a (Chl-a), sea surface height (SSH), wind speed, and precipitation (Pr) for Taiwanese-seine fishing vessels operating in the water off southwestern between 2012 and 2015. These data were further integrated and analyzed using geographic information system (GIS) and multivariate statistical analysis. The analysis of fishing activity data indicated 9 fish species, including moonfish (Mene maculate), spotted mackerel ( Scomber australasicu), jack mackerel ( Trachurus japonicus), yellowfin tuna ( Thunnus albacares), skipjack (Katsuwonus pelamis), finletted mackerel ( Megalaspis cordyla), round scad ( Decapterus maruadsi), bullet mackerel ( Auxis rochei), and pacific round herring (Etrumeus teres) accounted for the majority of total catch. During the summer season, catch abundance of skipjack and yellowfin tuna were relatively higher. During the winter season, catch abundance of jack mackerel and spotter mackerel were relatively higher. During the spring and autumn season, catch abundance of moonfish was relatively higher. With relatively higher catch abundance, fishing grounds were mainly located in the waters of 118°-121°E and 21°-23°N, 116°-118°E and 21°-23°N, and 118°-120°E and 23°-24°N. Fishing ground remained a north-southward shift from 2012 to 2014 and a east-westward shift in 2015. Principal component analysis (PCA) of catch abundance and environmental data indicated that he catch abundance of skipjack and yellowfin tuna were positively correlated with SST, SSH and Chl-a. The catch abundance of moonfish was positively correlated with SST and SSH. The catch abundance of spotter mackerel was negatively correlated with SST and SSH. The catch abundance of jack mackerel positively. correlated with Pr. Taken together, we have demonstrated that major targeted species and fishing grounds of Taiwanese-seine fisheries in the water off southwestern Taiwan vary spatially and temporally, which is likely associated with different oceanic conditions resulted from environmental changes. |
