CCAMLR

Basing on the analysis of major water mass boundaries and their thermochaline characteristics, T,S diagrams' typification has been realized for hydrological stations carried out in the area of South Orkney Isls and Shetland Isls in January-February since 1970. Three types of years have been singled out for the area of South Orkney Isls. The first type was characterized by presence of intermediate cold layer. In some years of this type (1 97 1, 1972, 1978, 1982) the layer had positive temperature, while in other years (1980, 1981) the layer temperature was negative. The second year type (1979, 1984, 1987) was characterized by rather narrow range of water temperature from the surface to the bottom, being observed at the same time, higher salinity. The third type (1970, 1976, 1984, 1989) was characterized by higher degree of principal water mass mixing within the area and lack of distinct boundaries between the same. Two year types were revealed in the area of South Orkney Isls. Availability of a warmed up layer of summer modification and a cold intermediate layer was characteristic of first year type. Lack of surface water of summer modification was characteristic of second year type (1 970, 1979, 198 1, 1985, 1989).
As water structure within those areas was considered to be the consequence of hydrodynamics processes and an indirect index of hydrodynamic situation observed, the results of typification could be used when analysing krill aggregations' distribution and density for the period of years under examination.

There were carried out hydroacoustic, biological and oceanographic surveys in subarea 48.4 near South Sandwich Islands. The main water masses were revealed and their boundaries determined: waters of Antarctic Circumpolar Current, Weddell Sea and Secondary Frontal zone of Weddell Gyre. The schematic maps of geostrophic waters circulation are made. The joint analysis of environment parameters and krill distribution is carried out. There are determined three krill groups which differ each other by length frequency, maturity stages and waters inhabited. Distribution of the 1st krill group (juveniles 25-29 mm) well corresponds to meanders of Weddell Current to West of archipelago and distribution of the 2nd group (41 -47 mm) to Frontal Zone of Weddell Gyre. In small eddies on FZWG boundary takes place concentration of krill of the 3rd group (50-56 mm) transported there by ACC waters. Such concentrated schools are transported to South from East of archipelago, and may be mixed with krill of the 1st group. It is very probable that krill concentrated in stable eddies to East of archipelago may be kept there for a rather long time, maturation and spawning may take place. Newborn larvae may drift further providing krill recruitment for the range parts situated down the Current

A precautionary catch limit for krill was established for CCAMLR Division 58.4.1 in 1996 based on the results of an acoustic survey (BROKE) of the southernmost 873,000 km2 of this area (CCAMLR 1996). Detailed subsequent analysis of the results of this survey have indicated that Division 58.4.1 is not meridionally homogeneous in its oceanographic or biological characteristics. Division 58.4.1 can be divided into two approximately equal sized subdivisions: 80-115?E and 115-150?E on the basis of environmental data. Krill is more abundant in the western subdivision and its biomass is more latitudinally extensive in this area. This observed pattern appears to be historically stable. Because of the unequal distribution of krill in this Division, and because of its extremely large size (4.68 million km2) we propose the formal subdivision of Division 58.4.1 into two based on the analysis of the scientific data collected on BROKE. The revised krill biomasss estimates for these areas are: 3.04 million tonnes for the western portion and 1.79 for the eastern one. We suggest the calculation of new precautionary catch limits for the two subdivisions of Division 58.4.1 based on the revised krill biomass estimates.

This paper describes the current status and possible further development of the CCAMLR Website as it is used to support the work of WG-EMM.

The development of CEMP indices derived from visual data (indices F1, F3 and F4), automatic weather stations and satellite imagery is explored with reference to the CEMP sites at Edmonson Point (Terra Nova Bay, Ross Sea, Subarea 88.1) and Béchervaise Island (Mawson, Eastern Antarctica, Division 58.4.2). Possible links between the extent or sea-ice adjacent to CEMP sites, weather conditions at or near CEMP sites, and the dynamics of penguins during the breeding season are discussed.

The CCAMLR Ecosystem Monitoring Program uses indices derived from data on indicator species and the environment collected by standard methods within the three Integrated Study Regions of the Convention Area. Standardised index values are re-calculated each year as new data become available, and trends and anomalies in these data are presented.

Fisheries targeting krill (Euphausia superba) in the CCAMLR Convention Area during 1998/99 caught 103318 t of krill, and preliminary information indicates that the catch in 1999/00 will exceed 82913 t. Krill caught in 1998/99 was taken in Subareas 48.1 (38% of total catch), 48.2 (49%) and 48.3 (13%). As in recent past years, only grounds in Area 48 were fished. Catch and effort data and observer data submitted to the Secretariat are discussed, together with other information on krill obtained at the request of WG-EMM.