This study was based on the data from the ichthyoplankton survey made in March-April 1989 by R/V "Vozrozhdenie" in the subtropical frontal zone over the South Atlantic ridge crest between 38°30’ - 45°S. and 15° - 20°W. Larvae were collected with BONGO and JUDAY nets in oblique arid vertical hauls at 500 - 0m. The method of delta-distribution of random values (Aitchison, Brown, 1957; Pennington, 1983) was used to count the larvae. The data obtained was taken to estimate the recruitment biomass (fish aged up to 1 year) in this species for the area of 87750 square miles studied. The abundance of larvae in this area was 4.3 x 10 ind., while the biomass of one year old fish obtained was 10750 tons. A whole chain of similar reproductive grounds is assumed to exist in the notal zone of the Atlantic and other sectors of the South Ocean to be able to sustain a large biomass of E. carlsbergi in waters of the south po1ar frontal zone.

Positions of commercial krill operation for 1980/81 season to 1998/99 season in the area to the north of South Shetland Islands were analyzed by using GLM (generalized linear model). Fishing season, the timing, and the longitude were significant factors to explain the variability of latitudes where operations were undertaken. Operations tended take place in the north in early 1980s, but from mid-1980 onwards, they tended to happen in the south, with exceptions of 1994/95 and 1995/96 seasons. Predicted latitudes of operation significantly correlated with Salp densities in the Elephant Island area (Spearman's rank correlation , p<0.05), but not with krill densities. This may be due to the intention of fishing vessels to reduce the salp in the products.

The paper covers the-results of an acoustic estimation of distribution for krill and non-krill zooplankton within the area of South Sandwich Islands that has been obtained with multy-frequencies algorithms according to the data on survey by Russian vessel ATLANTIDA under CCAMLR Survey-2000. Distribution of acoustic characteristics for krill and non-krill fractions of antarctic zooplankton has been compared. It has been showed that within the field locations occupied by waters of the Weddell Sea and Frontal Zone of Weddell Gyral the bulk of zooplankton had been made of krill, while non-krill fraction dominated in water masses of the Antarctic Circumpolar Current.

Spawning by Antarctic fish is generally considered to be seasonal and restricted to a brief period during the autumn and winter. Arising from this it has been assumed that the gonadal maturation cycle is also closely tracked to the time of year. The gonad maturation cycle of the mackerel icefish, Champsocephalus gunnari, was investigated using data collected during research surveys and from sampling the commercial fishery. Spawning appears to occur at the same time each year, but the timing of gonadal development is subject to a considerable inter-annual variation. The implications of this variation are discussed with respect to feeding conditions.

Mackerel icefish are widespread on the South Georgia shelf, Antarctica and have been subject to commercial fishing since the early 1970s. They are known to feed predominantly on krill. An index of condition which uses the ratio of the measured total mass to the estimated mass is show to provide a good indicator of local krill density. The index is likely to be little affected by the reproductive cycle unless there is high krill availability during the months around the spawning time and even then the effect is much less than the highest observed values The condition index responds rapidly to changes in hill density and therefore can provide indications of short term variations in krill availability. Condition index provides a useful proxy for krill density that is likely to be of considerable value in interpreting the results from ecosystem assessments such as that in progress under the auspices of the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR).

Net samples data from the 15th Italian Antarctic Oceanographic Cruise (Jan-Feb 2000) were analysed to obtain a general picture of the summer distribution pattern, abundance and demography of krill in the western Ross Sea (Antarctica). A midwater sampler-trawl (Hamburg Plankton Net) was used to collect zooplankton and fish larvae at 63 stations. The net was deployed normally as a standard double oblique tow. Mean relative biomass of Antarctic krill Euphausia superba, in the area north of Continental Shelf, was 9.4 (±18%) g/l000m3 of filtered water with a mean density of 11.0 (±16%) indviduals per 1000m3. The high abundance of Euphausia superba (1510 g/1000m3) found in a single haul on the Mawson Bank Area (73°S 173°E) was remarkable. Ice krill Euphausia crystallorophias replaced the Antarctic krill in dominance in the High Antarctic Zone (south of 74°), with a mean relative biomass of 3.0 (±26%) g/l000m3 and mean density of 16.8 (±10%) individuals per 1000m3. The present data have demonstrated that in the Ross Sea during the summer period, the two species of euphausiid inhabit different areas. Lengths of Ice krill and length, sex and reproductive stage of Antarctic krill occurring in discrete aggregations were analysed. This indicated that the composition of the aggregations in terms of the mean length, sex ratio and maturity stage were very variable. The catch data of Euphausia superba was characterized by the complete absence of larval stages, scarce occurrence of juveniles and composed primarily of large adult stages. From the analysis of the krill population structure it emerged that in mid summer, Euphausia superba of age 3+ and 4+ were clearly predominant. While the overall length frequency distribution of Euphausia crystallorophias is characterized by a first mode of juvenile individuals (Age class 1 +) and a second mode consisting of sub-adults and adults (Age groups 2+ and 3+).