CCAMLR

The annual Random Stratified Trawl Survey was undertaken in Division 58.5.2 in the vicinity of Heard Island during April-May 2011. This paper provides a preliminary assessment of mackerel icefish population structure, abundance and yield for the area of Division 58.5.2 to the west of 79^o 20’ E using standard CCAMLR methods. A pattern of 5 year classes being present simultaneously in the population, which was first detected in 2011, has persisted, however a large cohort of fish, estimated to be 2+, dominate the population in both abundance and biomass. A new length weight model is estimated which indicates fish in the 2012 survey were heavier on average than predicted by the previous length weight model. Sensitivity testing indicates that the approach of using the lower 95th percentile of the biomass estimate effectively accounts for uncertainty in growth and mortality, relative to scenarios using the mean biomass estimate. A catch limit of 679 t is recommended for the 2012/13 season.

The annual random stratified trawl survey at HIMI was completed in March to May of 2012. A codend liner, usually in place for the entire survey, was used only in the icefish strata, Gunnari Ridge, Plateau Southeast and Plateau West, and in a repeat of the hauls in Ground B. Catches in this RSTS were generally high in comparison with previous years, with the total fish catch being twice as high as the long term average (2006-2011). The catches of Dissostichus eleginoides for 2012 were twice those of 2011 and about one and a half times higher than the long-term average. Champsocephalus gunnari catches were twice the long term average. Catches of all the major fish species were higher in 2012 than the long-term average, except for those of Channichthys rhinoceratus which was 10% lower. The catch of Lepidonotothen squamifrons was four times higher than the average. A slightly higher than average weight of skates was also taken in 2012.

The catch of invertebrates in the 2012 survey, 4 t, was about half that of the long term average. The most abundant taxa in the catches were poriferan sponges, medusa (jellyfish), anemones and corals. Catches of individual taxa were generally much lower than in previous years, except for coral, with a reported catch of 0.6 t, being significantly greater than the long term average (50 kg). A possible explanation for the generally lower catches is that the smaller mesh codend liner was not in place for most of the survey.

Lengths and biological measurements were taken for many thousands of fish, 1095 pairs of otoliths collected and 524 toothfish were tagged.

The unicorn icefish, Channichthys rhinoceratus and the grey rock cod, Lepidonotothen squamifrons are among the most common species bycaught in the toothfish and mackerel icefish trawl fisheries at Heard Island and McDonald Islands (HIMI) (Division 58.5.2). These species are rarely taken in the longline fishery, but form the most abundant bycatch of the trawl fisheries after skates (Bathyraja spp.). In the toothfish fishery both species are taken, whereas C. rhinoceratus is much more common in the bycatch of the mackerel icefish fishery than L. squamifrons. Over the 15 years of the fisheries, approximately 20 t of C. rhinoceratus and 9 t of L. squamifrons were caught annually. The commercial and research data analysed in this study shows that both species are widespread over the plateau in waters of <1000 m. In most areas they occur at densities <100 kg.km^-2, but each species has separate areas of aggregation where densities exceed 1 t.km^-2. The annual take of these species is well below the precautionary bycatch limits set by CCAMLR, move-on rules apply, and a substantial part of their distribution occurs within the HIMI Marine Reserve, and therefore current bycatch levels are likely to be low risk. However, we intend to conduct a study of the population dynamics of these species to further evaluate the performance of current management measures.

Ocean circulation has been identified as a major process controlling the distribution of biological material in marine systems.  Large-scale transport by the Antarctic Circumpolar Current (ACC), the Ross and Weddell Gyres, and the Antarctic Coastal Current can promote spatially complex population structure in the Southern Ocean through advection.  Antarctic silverfish (Pleuragramma antarcticum), a pelagic, neutrally buoyant notothenioid fish species, are distributed around the shelf systems of Antarctica and are considered an important species rivaling krill as prey for many birds, seals, whales, and other fish. We asked whether silverfish are distributed in independent, discrete populations along the shelf systems of the Southern Ocean or whether the large-scale circulation has led to connectivity among populations.  Hypotheses were tested by measuring the chemistry, trace elements and stable isotopes, in silverfish otoliths, and comparing the chemistry with simulated particle transport using a high resolution circulation model.  The results showed strong heterogeneity indicating four separate populations: i) in the Ross Sea, ii) on the southern Antarctic Peninsula in Marguerite Bay and off Charcot Island, iii) off Joinville Island, and iv) around the South Orkney Islands. This suggested that silverfish are not transported by the ACC, shelf processes on the West Antarctic Peninsula (WAP), or along the Weddell Front.  Using the circulation model, we built spatially explicit predictions of advective supply to areas along the WAP, and examined how interactions between silverfish life history and the Antarctic Coastal Current may structure assemblages over the continental shelf.

Information about fish species composition from region near the Ukrainian Antarctic Station «Akademik Vernadsky» (Argentine Islands, Antarctic Peninsula) during wintering 2007-2008 is presented. The quantitative indexes of different species fishes and the analysis of their dominant groups were studied. New fishes subdominant was registry with help our researches. Trematomus bernacchii was subdominant in the previous years, but during our researches Notothenia rosii prevailed already. Biological and morphometrical analyses of two groups Notothenia coriiceps from the Meek-Penola Channel and near the west coast of Grotto Island are conducted. It is exposed, that these two groups of fish species divided, probably, on the different population. Somatic indexes did not show considerable changeability, except for hepato-somatic. Individuals of both groups’ species of fish had the low indexes of adiposeness and fatness.

This work is prepared in accordance with recommendation of 4.18 WG-SAM-12 about submitting of data on fishing gears` construction that was used on Russian longliners Sparta” and “Chio Maru №3”. The trotline of a special design that was used is formed of main floating line and fastened lines with hooks and weight. This design allows avoiding fish injuries outside the mouth cavity and catching of VME-organisms to a large extent, because at the presented design of a longline each line with a weight (“barandija”) has bunch of 5-10 snoods with hooks and length of a snood is 30-40 cm or sometimes less and when fish eats the bait and trying to get away making chaotic movements, it won`t be hooked by the body because of the shortened snood.