Some notes on by-catch of fishes caught by the fishery vessel Niitaka Maru in the vicinity of the South Shetland Islands (December 2000 to January 2001)

Scientific observations on fishes incidentally caught during commercial krill fisheries by F/V Niitaka Maru (3910t) were made from 16 December 2000 to 26 January 2001 in the vicinity of the South Shetland Islands. Among 103 net hauls quantitatively examined, by-catch fishes were found in 41 trawl catches. Lepidonotothen larseni was the most abundant in number and weight and occurred in 20.4% of hauls sampled for by-catch and 51.2% of those contained fish. P. antarcticum and C. gunnari were the second in abundance in number and weight respectively. Most hauls were dominated by one species which constitute 63.4% of hauls contained by-catch fish and a high degree of spatotemporal dissociation among juveniles of different species was recognized. The by-catch data of the present survey provided a clear picture of the negative correlation between abundance of by-catch fish and the krill CPUE. The relationship between towing time and estimated individual number of by-catch fish in each haul was obscure.