Preliminary results of RV Dmitriy Stefanov researches in the Antarctic area of the Atlantic Ocean in April 1992

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).