CCAMLR

The United States Antarctic Marine Living Resources (U.S. AMLR) program conducted bottom trawl surveys in March, 1998 of the two major regions of the South Shetland Islands: Elephant Island and the lower South Shetland Islands from King George Island to Livingston Island. Estimates of total stock biomass and spawning stock biomass were computed for six species: Champsocephalus gunnari, Gobionotothen gibberifrons, Notothenia coriiceps, Chaenocephalus aceratus, Chionodraco rastrospinosus, and Lepidonotothen squamifrons. Estimates of total stock biomass only were computed for two additional species: Lepidonotothen larseni and Notothenia rossii. Biomass was estimated for both regions separately, and combined as one system using previous and updated estimates of seabed areas for Elephant Island and the lower South Shetland Islands.

Maturity data information obtained by the scientific observers on board the ships Argos Helena and Cisne Verde during August of 1997 -and utilized by the WG-FSA-97 to build the maturity ogives- were age transformed applying the age-size relationship obtained from the specific equations for each sex in samples coming from South Georgia Islands. The results show that the differences are due to maturity at age and not due to the growth rate. Based on this sample of 434 females and 398 males, it is concluded that the males mature for the first time at 4 years age and females at 10 years age, reaching 100% maturity at 12 years age the males and 21 years age the females.

Bottom trawl surveys were conducted by the United States Antarctic Marine Living Resources program in two major regions of the South Shetland Islands: Elephant Island and the lower South Shetland Islands from King George Island to Livingston Island. Information on species composition, catch levels, size composition, and condition are described and compared between the two regions. Maturity ogives were constructed for five species of finfish: Champsocephalus gunnari, Gobionotothen gibberifrons, Chaenocephalus aceratus, Chionodraco rastrospinosus, and Lepidonotothen squamifrons. Estimates of length at sexual maturity and length at first spawning are computed and compared with previous estimates and other populations.

Bathymetric maps of two major areas within the South Shetland Islands were generated using several integrated bathymetric databases. These areas comprise the lower South Shetland Island chain from King George Island to Smith Island, and the region around Elephant Island. From the integrated data sets, areas of seabed within the 500 m isobath for six levels of depth strata (0-50 m, 51 - 100 m, 101-200 m, 201 -300 m, 301-400m, 401-500 m) were computed. Areas were calculated based on true surface area of seabed incorporating seafloor slope

The absolute and relative fecundity of Patagonian toothfish inhabiting areas of South Georgia Island and Shag Rocks were studied. The absolute individual fecundity of toothfish in relation to the size of specimens ranged from 56,3 to 567.5 thousands of eggs, averaging 152,9 thousands of eggs. Values of relative individual fecundity of toothfish varied from 4,1 to 13,0 thousands of eggs (averaging 8.19 ± 1,73 thousands of eggs ) per 1 kg of fish body weight. Our studies and the analysis of data published previously indicate, that Patagonian toothfish similar to the most of Notothenioids characterized by large eggs can be included in the fish group having a level of absolute fecundity and a low value of relative fecundity.