Some notes on by-catch of fishes and salps caught by the fishery vessel Niitaka Maru in the vicinity of the South Shetland Islands (January to February 1999)

Scientific observations on fishes and salps incidentally caught during commercial krill fisheries by F/V Niitaka Maru were made from 3 January to 4 February 1999 in the vicinity of the South Shetland Islands. Among 74 net hauls quantitatively examined, only a total of 5 specimens of juvenile fishes belonging to three notothenioid species, Notothenia coriiceps, Chaenocephalus aceratus and Chaenodraco wilsoni were found in 4 trawl catches. On the contrary, salps were captured as by-catch in 69 hauls and those estimated value was 20 to 3560 ind./t of krill. By-catch fishes fed on Thysanoessa macrura and Euphausia superba was not found in their stomachs. Abundance of salps in krill catches could have been depended on the density of krill concentration. At least, the large incidental catch of salps (>2500 ind./t of krill) occurred in hauls with the low krill catch rates (<5 t/h). Relationship between abundance of salps and fishing time could not be recognized.