A finfish survey was completed using bottom trawl fishing gear according to 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). The sampling stations were set in approximately the same geographical coordinates as those on previous R/V 'Polarstern' surveys around Elephant Island (Kock & Jones, 2012) and on shelf areas of the South Orkney Islands according to a subsample of stations sampled by the R/V 'Yuzhmorgeologiya' (Jones & Kock, 2009).
The cruise took place 6-27 January, 2018, primarily using a Hardbottom Snapper trawl (NET Systems, Inc.), previously used by the US AMLR Program, Southwest Fisheries Science Center, National Marine Fisheries Service. A total of 36 hauls were carried out with this bottom trawl, 15 around Elephant Island and 21 around the South Orkney Islands. Additionally, eight hauls were conducted using either a Casanova bottom trawl (3 hauls) or a Gloria 704 midwater trawl (5 hauls).
For stations sampled using the Hardbottom Snapper trawl, 36 fish species were caught with a total volume of 19,112.28 kg. The main species extracted with this gear corresponded to Notothenia rossii and Champsocephalus gunnari, with landings weighing 16,204.38 (84.79%) and 875.69 kg (4.58%), respectively. Other species of fish registered noticeably lower amounts (10.63%), such as Gobionotothen georgianus (329.97 kg), Chaenocephalus aceratus (321.91 kg), and Pseudochaenichthys georgianus (299.39 kg).
As a result of nearing the maximum research catch specified in Subarea 48.1 (95% of authorized research catch), we were unable to complete the planned number of bottom trawl stations (n=37), with 35% of proposed stations completed (n=13). In Subarea 48.2, we were unable to complete the planned number of stations (n=28) because of limited ship time, where 75% of proposed stations were completed (n=21). This resulted in a very low sample size with which to estimate standing stock biomass, and thus results presented here should be taken as indicative. Indicative estimates of standing stock biomass suggest that N. rossii is the most abundant demersal finfish species in the Elephant Island area followed by C. gunnari. On the South Orkney Island shelf, the most abundant species was G. gibberifrons followed by P. georgianus.
The acoustic survey was carried out around both groups of islands and its processing will contribute to knowledge regarding bathymetry and distribution of the concentrations of fish and krill in the studied area (track of 579 nm around Elephant Island and 1,120 nm around South Orkney Islands). During the acoustic survey, five hauls were carried out with a mid-water trawling net in order to identify the shoal marks registered in the echo sounders. One of the mid-water hauls identified a shoal of icefish (33.6 t), while the other four obtained other species of icefish, such as P. georgianus, and krill.
In addition, 1,176 tissue samples representing 21 species of nototenoids, four species of the family Rajidae, and another 12 species that make up six families of teleost fishes were collected for genetic studies. A further 1,182 specimens were evaluated for parasite infestation (Euhirudinea), with 140 specimens of Trulliobdella capitis,Truliobdella bacilliformis, and Nototheniobdella sawyeri collected.