An assessment of the impact of krill fishery on penguins in the South Shetlands
An assessment of the competition between the Japanese krill (Euphausia superba) fishery and penguins during the penguins' breeding season (December to March) in the South Shetland Islands (Subarea 48.1) was made based on available information on the fishery, penguins and krill. The krill catch is very low in December while the catch rate for the following three months is roughly constant (3 000 to 10 000 tonnes/10-day period) due to an increase in fishing intensity in areas closer to the northern shelf of either Livingston or Elephant Island. In contrast, food consumption by penguins is estimated to be high to the north of King George, Nelson and Robert Islands (9 746 tonnes/10-day period), and around Low (6 102 tonnes/10-day period) and Clarence (5 663 tonnes/10-day period) Islands, but small to the north of Livingston (1 921 tonnes/10-day period) and Elephant (1 991 tonnes/10-day period) Islands. Thus, the overlap between the main fishing and foraging areas is insignificant and implies a low level of competition between the fishery and penguins. Krill biomass was estimated to be as large as 200 to 1 500 x 103 tonnes within the preferred fishing areas during the breeding season. Compared with the level of biomass (≥200 x 103 tonnes) and its variability (the order of 100 x 103 tonnes/10-20-day period), the present catch rate (≤10 x 103 tonnes/1O-day period) is smaller by one or more orders of magnitude within the localised areas. Thus, the present fishery is very unlikely to have an adverse impact on the local krill biomass, and hence on penguins, when catch levels are also taken into account.