Antarctic demersal finfish around the Elephant and the South Orkney islands: distribution, abundance and biological characteristics

Abstract

. A research survey for demersal finfish was completed using bottom trawl fishing gear, following a random stratified sampling design, between 50 and 500 m on shelf areas of Subarea 48.1 (Elephant Island) and Subarea 48.2 (South Orkney Island). An acoustic survey was simultaneously carried out to enhance knowledge of bathymetry and the distribution of fish and krill in the studied area. The cruise took place between the 6 and 27 January 2018. A total of 36 hauls were carried out, 15 around Elephant Island and 21 around the South Orkney Islands. A total of 37 fish species were caught with a total biomass of 19,112 kg. The main species encountered included Notothenia rossii and Champsocephalus gunnari, with nominal catches weighing 16,204 (85%) and 876 kg (5%), respectively. Other species of fish accounted noticeably for lower amounts (11%), such as Gobionotothen gibberifrons (330 kg), Chaenocephalus aceratus (322 kg), and Pseudochaenichthys georgianus (299 kg). Indicative estimates of standing stock biomass suggested that in this cruise, N. rossii was the most abundant demersal finfish species in the Elephant Island area, followed by C. gunnari. Differently, on the South Orkney Islands shelf, the most abundant species was G. gibberifrons, followed by P. georgianus. The study provides biological data (length frequency distribution, median size, sex ratio, gonad maturity stages, length-weight relationship) on the main species captured during the survey, and the oceanographic characteristics (depth profiles of temperature, salinity, density) obtained with CTD around the South Orkney Islands.