Abstract: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.
