Preliminary results on by-catch of fishes caught by the fishery vessel Chiyo Maru No. 3 to the north of the South Shetland Islands (February to March, 1996)

Investigations on by-catch of fishes captured during krill fishing by F/V Chiyo Maru No. 3 were made from 3 February to 6 March, 1996 to the north of the South Shetland Islands. Among 147 hauls examined, a total of 99 specimens belonging to 5 families and 14 species were captured as by-catch in 41 hauls. Notothenioid juveniles were found in 30 hauls carried out in waters with a depth of 87-853m (average 186m). On the contrary, bathypelagic fishes (myctophids and paralepidids) were recognized in 11 hauls operated at some distance from the shelf, in the offshore waters with a depth of 275-1780m (average 1006m). Notothenioid juveniles never caught with bathypelagic fish species in all hauls examined. Among by-catch fishes, juvenile Lepidonotothen larseni was the most abundant. This species was found in 15 hauls, and its estimated value of an arithmetic mean was 4±19 ind./t (0 to 140 ind./t) of catch and 51±217 ind./h (0 to 3927 ind./h) trawling respectively. Bathypelagic fish species, Electrona carlsbergi, which was found in samples from 6 hauls, was the next in abundance. Its arithmetic mean was 3±21 ind./t (0 to 220 ind./t) of catch and 32±178 ind./h (0 to 1509 ind./h) trawling. Although the krill CPUE of hauls without by-catch of fish ranged widely, the large incidental catch of fish usually occurred in hauls with lower krill CPUE.