夏、秋季巴塔哥尼亚大陆架公海海域拖网渔获物组成及主要种类生物学特征

Analyses on Species Composition and Diversity of Trawling Catch in Patagonia Continental Shelf High Seas During Summer and Autumn

中文关键词: 巴塔哥尼亚大陆架  渔场环境  底拖网  渔获组成

英文关键词: Patagonia Continental Shelf  Environmental characteristics  Trawl  Catch composition

中文摘要:

      2011年1-3月，在巴塔哥尼亚大陆架公海进行了拖网探捕。本次调查海域位于巴塔哥尼亚大陆架海域渔场边缘，毗邻福克兰-马尔维纳斯大陆架海域渔场，渔获组成兼有这两个渔场的特征。结果表明，该渔场(45°01′-46°53′S，60°07′-60°47′W)底质平坦，水深在110-180 m之间，调查期间天气良好，适宜底拖网作业；在水深20-80 m水层存在温、盐跃层。底拖网渔获中主要有11种经济种类，按渔获量排序以阿根廷滑柔鱼(Illex argentinus)、拉氏南美南极鱼(Patagonotothen ramsayi)、阿根廷无须鳕(Merluccius hubbsi)、阿根廷鳀(Engraulis anchoita)与鳐类列前五位，占总产量的92.26%。探捕期间，相对资源量指数1月平均为(462.8±95.7) kg/h，2月平均为(713.8±194.1) kg/h，3月平均为(778.1±75.0) kg/h，呈逐月递增趋势。经济种类的数量分布有较大差异，多数经济种类的资源密集分布区位于渔场北部，渔场南部高产种类较为单一。阿根廷滑柔鱼优势胴长有逐月增大的趋势；阿根廷无须鳕优势体长变化不明显；拉氏南美南极鱼的优势体长皆小于其初次性成熟体长，其中1月采集的样本仅为110-130 mm，分析认为，本调查捕获的多为索饵洄游的幼鱼。

英文摘要:

      The high sea fishing grounds of Patagonia Continental Shelf is rich in fishery resources. There have been reports on squid fishing in domestic fishery, but study on trawl resources has been lacking. In this study, we analyzed the dynamics of the environmental characters, the fishery resources, the species composition as well as the biology of the dominant species. This study was based on the monthly bottom trawl surveys between January and March in 2011. The fishing grounds (45°01′−46°53′ S, 60°07′−60°47′ W) of Patagonia Continental Shelf high seas had a flat bottom and the depth of water was 110−180 m. The weather condition was good during the survey. This area was suitable for bottom trawl. There was a thermocline and halocline at 20−80 m underwater. This area was located at the edge of Patagonian Continental Shelf Fisheries which was adjacent to the Falklands - Malvinas Continental Shelf Fisheries. Hence the catch composition had the combined characters of both fisheries. The trawling catch was composed of 11 economic species, and Argentine shortfin squid (Illex argentinus), rock cod (Patagonotothen ramsayi), Argentine hake (Merluccius hubbsi), Argentine anchovy (Engraulis anchoita) and the skates accounted for 92.26% of the total. The average relative resource index (RRI) was the lowest in January and the highest in March. The results suggested that these fisheries were suitable for bottom trawling; the northern and southern parts of the fishing grounds were very different in species composition and the resource density, and the northern part had a more diverse and abundant resource. The dominant mantle length of I. argentinus increased from January to March, but that of M. hubbsi did not change over time. The dominant body length of rock cods was shorter than the length when they first became sexually mature, and their length was only 110−130 mm in January. It was most likely that the majority of the catch in this survey were feeding migratory juveniles.