CCAMLR

The oceanological, hydroacoustic and trawling surveys were carried out within the polygon of 30 x 30 miles in the fishing area northwestward of Coronation Island in 18-22 April,1992. The krill biomass was estimated in the beginning and at the end of surveys. It amounted to 56.1 and 61.2 thous. t respectively. During the rest of the period the hydroacoustic assessment of krill aggregation density and oceanological stations were carried out along the square perimeter. There were four dublicates of perimeter. The midwater trawl hauls were made periodically. The average estimates of krill aggregation density by 15-mile perimeter sections, average water flow and scheme of geostro-phycal currents were obtained. The balance of krill transport from and into the polygon was calculated. The first two dublicates revealed the krill accumulation in the contour, and the second two showed the loss. The accumulation was 52 thous. t as high as the loss. The researches pointed out that fishing aggregation stability is mainly determined by the water dynamics, such as the availability and duration of heterogenity in the current fields. From 25 to 27 April 1992 three hauls with fishing bottom trawl were made to collect data on size and age composition of icefish, champsocephalus gunnari, green notothenia and yellowfin notothenia over the shelf of South Georgia and Shague rocks. The researches were carried out by H/V "Dmitriy Stefanov" ovmed by PPO "Yugrybpoisk" (Ukraine).

Calculation of drift’s speed (transport with current) of Antarctic krill along the northeastern shore of South Georgia Island (between 54-55S and 34-39W) were carried out. Length of island’s shelf for calculation was assumed about 300 km, but average width of shelf (from shore to 500 m isobate) was assumed about 60 km. Speed of drift in these spatial limits was assumed about 10 cm sec-1. The average density of krill before the beginning of transport along the island’s shore was assumed about 0.1 g m-3.
Total amount of krill immigration on island’s shelf (in above indicated limits) were examined for three main types of water circulation (the typisation according to Maslennikov, 1979).
Duration of krill drift (from the beginning of immigration and to the end of emigration) along the northeastern shore of South Georgia fluctuated from 35-37 days to 75-100 days. For separate cases this duration was valuated as much as 140-150 days (when crustaceans are transported back again on shelf zone at the conditions of the first type of water circulation). The minimal period of krill presence near island is expected for the third type of water circulation, but maximal duration of krill presence here is suggested for the first type of water circulation. Total renewal krill, which is immigrated into shelf waters of island is supposed to take place not less than 2-3 times per year. Peculiarities of accumulation and drift of krill related to the consequence of types of water circulation change are examined.

Data on distribution and biomass of E.superba aggregations at Atlantic sector and near adjacent waters (subregions outside of the Scotia Sea are under pecular attention) are observed° Concentration of E.superba of the same order of biomass volume as in the Scotia Sea were observed at several subregions along the peripherie of Weddell Gyre and also nearshore of Antarctide. Offshore concentrations of E.superba show increased spatial irregularity. Development of fisheries activity in these new for catching areas should include the preliminar getting of knowledges on changeability of E.superba aggregation distribution prior to practical using of observed pattern of that changeability. It requires of additional complex of investigations, which should be directed to the evaluation of drift ways of E.superba as well as related changeability of aggregation location in the open-ocean environment. Exploitation of offshore aggregations of E.superba will be connected with regular search activity prior as well as at the course of every fishery season (year).

Microscale data, described the Soviet krill fishery off the Elephant Island (Subarea 48.1) between 59°-62°S and 53°-57°W during the period from 21.11.1988 to 25.03.1989, are analysed. Though the catch of the USSR in the above-mentioned season reached maximum, the total fishery intensity for the last 9 seasons was low and only 1 standard vessel operated in the area during 40% of the period. The highest catch per-unit-of-effort was observed in January (7.7 t per hour of trawling in average), and the lowest in November (3.5 t per hour of trawling in average). Fisheries tacktics follows the scheme: 1) vessels enter the Elephant Island area and search for krill concentrations; 2) fishing of concentrations, drifted from the Island, and return into the initial area when the concentration has been lost. The velocity of krill concentration northeastward drift, calculated by the fleet displacement amounted to 9.7-11.1 km/day (11-13 cm/sec). The analysis of fishing ground allocation by five-day periods showed that fleet operation areas in general overlap the minor part of foraging zones for animals, preyed on krill. Based on this and taking in account low fishery intensity the conclusion was made that current krill fishery insignificantly affect the seals and birds, preyed on krill.

A nest ANOVA design was used to measure the variance component due to differences between individual penguins in the length of krill eaten by Adélie penguins at Esperanza Bay. The value found was not different from zero: variance component = -0.16; F = 0.93; P = 0.54. This finding supports the use of individual penguins to estimate parameters of the prey population without discriminating by sex, weight or other factors pertaining to the predator.

Since parameters of penguin populations may provide good indices of the abundance of the key prey species (krill) and thus the state of the Antarctic marine ecosystem, aerial reconnaissance and photography are used in the Ross Sea sector of Antarctica to determine where Adelie penguins (Pygoscelis adeliae) breed, and to count the numbers of nests occupied during the early incubation period and surviving chicks in mid-January (when weight and measurements of samples of chicks at Capes Royds and Crozier give a condition index). From 1981 to present, all islands and sea coasts between 158°E and 175°E were searched, and 12 previously unreported breeding rookeries were discovered. Thirty-nine Adelie rookeries are now known from the region, with a total of about 1,082,000 breeding pairs - almost half the world population. Some rookeries are photographed in all, or most, of the seasons to study the pattern of natural population fluctuations. Populations at nearly all rookeries have increased markedly in size over the last 10 years. Possible reasons for this, and for annual fluctuations in numbers breeding, include seasonal variations in sea ice and weather conditions, and longer-term climatic change. This study identifies the need for complementary Ross Sea baseline studies including: studies of primary productivity and effects of ice thickness and UV radiation, climate change, krill distribution and abundance, seasonal distribution of sea ice, air temperature at sites remote from continental influence, and satellite tracking of radio-tagged penguins to study foraging range and winter dispersion.
In 1992/93 we propose repeating the photographic surveys of rookeries on Ross Island using helicopters in December and January to count incubating adults and surviving chicks, respectively. Rookeries north of Ross Island will be photographed from an RNZAF C-130 in December. Details of methods and logistics are discussed.
In New Zealand, developing, printing, collating, filing and counting all photographs of study rookeries is completed each season.