CCAMLR

The random stratified trawl surveys (RSTS) for 2008 and 2009 were successfully completed on the RV Southern Champion, continuing the series that commenced in 1997. Catches in 2008 were generally reduced from the previous year’s survey, with the catch of toothfish being one third of that for the previous year and those of grey rock cod, unicorn icefish and skate species down by half. Catches of mackerel icefish and macrourids were similar to the previous RSTS. One of the most notable features of the survey was the very large catch of jellyfish. In contrast, overall catches for the 2009 survey were much higher than those from the 2008 survey. The total catch of fish was three times higher than that of 2008, with the catches of toothfish and icefish being four and five times higher respectively, and catches of skates being twice that of the 2008 level. The 2009 catches were closer to the average of the previous three years when there has been a stable survey design.

A survey of mackerel icefish, Champsocephalus gunnari, was undertaken in Division 58.5.2 in the vicinity of Heard Island in April 2009 to provide the information for an assessment of short-term annual yield in the 2009/2010 CCAMLR season. This paper provides a preliminary assessment of yield for the area of Division 58.5.2 to the west of 79o 20’ E using standard CCAMLR methods. The strong year class detected in the last two years’ surveys is now fully recruited as the 3+ cohort, and dominates the population.

Scales and whole otoliths were read for age determination of early stages of Notothenia rossii caught in Potter Cove, South Shetland Islands, in summer of years 2003-2006 and 2008. The sample was composed by blue phase fingerlings of 7-7.6 cm (TL) and age group 0 year and demersal young brown phase juveniles of 8.5-20.9 cm and predominant age groups 1-2 years. Counting of sclerites facilitated the interpretation of the rings, particularly in the central area of the scale. To clarify two issues of controversy in the literature: 1) we believe that the duration of the pelagic fingerling stage at sea is less than one year before migration to the demersal nearshore habitat; 2) the first well defined ring in scales corresponds to the first annulus, while a contiguous nearby ring is a secondary ring deposited after the first winter during the second year, attributable to a shift of habitat from pelagic to demersal. Our inferences, based on interpretation of the distinct sclerite structures that constitute the rings, are illustrated/supported by photographs. A von Bertalanffy growth curve was computed by combining age/length data of the juvenile phase of N. rossii from this and a previous study at Potter Cove, with literature data from the offshore adult population, resulting in the equation:

This paper summarized the chilean catch data for 1991. Especial emphasis is given to the analysis of haul-by-haul data and its use in understanding small scale spatial distribution of fishing grounds. The results show that the krill fishery in subarea 48.1 is particularly intense near CEMP sites. Other uses of haul-by-haul data are suggestted.

Length composition of krill in diurnal and night hauls of FV Lepus, off S. Orkneys in January and February 1991, generally show similar pattern. The proportion of bigger individuals of krill in night hauls was slightly higher than within diurnal hauls. CPUE values in February were higher than those in January. No larval fish were recorded in krill catches. Only few specimens of Electrona antarctica (of length range 53 - 103 mm) were found in some night hauls.

Four Polish commercial trawlers participated in the krill fishery in 1990/91 season on the fishing grounds in statistical Sub-areas 48.2 and 48.3. In total 9 333.7 tonnes of krill were harvested. As the fishery data were not fully analysed yet no clear trends in catch-per-unit-effort for different fishing grounds during the season could be detected.

Krill swarms were recorded acoustically along a 2340 Nm of the ice edge between Elephant Island and South Orkney Islands. Depth distributions and migration pattern were different for the three distinguished regions. It has been sugested that physical factors are the most important in both :horizontal and vertical krill distributions.