CCAMLR

It has been showed that krill spatial distribution in 48.4 Subarea was characterized by presence of non-aggregated and scattered form, swarms, when surveying (January 17-February 1, 2001).. There have been revealed differences between spatial distribution patterns of krill aggregations of different type in relation to water mass structure and dynamics.
The distributional features and physical characteristics of some 2400 krill swarms detected and sized acoustically in the study area have been described. Comparative results have been given between swarm parameter means in different areas and seasons.
There has been made an analysis of krill biomass horizontal and vertical distributions in the study area in relation to characteristics of the aggregations recorded. The effect of spatial distribution of krill aggregations of different type had an on krill biomass horizontal and vertical distribution has been shown. Major krill biomass (of about 64%) was concentrated in krill swarms within the meander and eddies zones of the Weddell Sea (14% of study area), being observed in upper 80 m depth level.
There has been made an analysis spatial distributional patterns of krill aggregations of different type and vertical distribution of krill biomass density with a view to revealing potential fishing grounds to remove the recommended precautionary catch limit. There have been revealed that potential fishing grounds could be situated within the zones of swarms concentrations where biomass density was than 1.5g/m^3. Biomass in the potential fishing grounds amount about to 1,7 mln.t It has been manifested that biomass removal corresponding to recommended precautionary limit could be possible from such grounds , however, the predicted catch per trawling hour is low
Therefore, the investigations carries out demonstrated a practical interest in studying spatial distributional patterns of krill aggregations of different type to acquire knowledge in natural regularity of krill biomass horizontal and vertical distribution and to reveal potential fishing grounds to remove the recommended precautionary catch limit. The latter is an important link for regulating fishery according to the adopted ecosystem approach.

Substantial improvements in data collection and analytical methodologies of acoustic krill surveys have taken place for the recent twenty years. It has been attempted to determine the influence of such improvements on krill biomass estimation. The letter seems to become useful in comparative analysis of krill biomass data from the results of different acoustic surveys.
There have been presented the results of krill biomass comparative estimation by single-frequency and double-frequency algorithms that were obtained by processing data on Russian R/V ATLANTIDA surveying in 48.4 Subarea according to CCAMLR 2000 Krill Survey .
It has been demonstrated that application of different methods to krill species identification realized by single-frequency and double-frequency algorithms could cause a marked difference in krill biomass estimates. A difference was more than 1.8 times in the case under consideration.
Judging from significant differences in biomass estimates attributed to only introducing a new method of krill species identification, one may suggest that other improvements for recent twenty years could also have a considerable influence on biomass estimates obtained . Therefore. it is expected that the analysis of interannual and interseasonal krill biomass variability by results of acoustic survey is to be done taking into account improvements in data collection and analytical methodologies.
One may not exclude that differences in FIBEX-1981 and CCAMLR-2000 krill biomass estimations are rather attributed to the improvements in acoustic sampling and processing survey data than to the variations in krill stock of Subarea 48.

Krill sampling were carried out Northwest and Northeast South Georgia, first during collaborative venture AtlantNIRO-BAS on 5-8 January and 10-13 January and then during fish bottom trawl survey on 22 February and 3 February correspondingly. The comparative analysis revealed the strong difference in krill inhabiting Northwest and Northeast South Georgian waters. According to the data available the difference do not disappear in time, instead certain increase of krill length was observed in both parts. The data analyzed confirm that krill on the Northern South Georgian shelf has different origin: krill is transferred to east shelf by Weddell Sea waters and to west of the Island by Antarctic Circumpolar Current Waters from the West; Western krill belongs to cluster 2 and Eastern one to cluster 1.

Published information on conversion factors to estimate krill removals from the amounts of different krill products are examined and a range of values produced. These are broadly in line with those currently in use although the differences are such that use of the traditional factors may introduce large errors into the estimation of removals. It is uncertain whether discarding is a common practice in the fishery, if it is then the use of any of the conversion factors will result in a serious under-estimation of total removals.

Japan has deployed one scientific observer on a Japanese krill trawler, Niitaka Maru, from 13 December 2000 to 26 January 2001. The observation was undertaken following the CCAMLR Scientific Observers Manual. Summary of the fishing efforts, processing, fish by-catches, biological measurements of krill, product types are described in the report. The trawler made an anti-clockwise trip around the South Shetland Islands. During this trip, the vessel encountered a swarm rapidly moving southwards. Also, they encountered icebergs twice, and caught some small sized krill around them, which they could not catch in the other locations. The patches seemed to be relatively dispersed compared to the previous season.

This document is to announce our intension to hold ‘Workshop on krill culturing techniques’ at Port of Nagoya Public Aquarium, Japan, in September 2002. Port of Nagoya Public Aquarium recently succeeded in reproducing and raising Antarctic krill up to juvenile stages under an artificial condition. Several research groups in the world are also independently developing their culturing techniques. Developing techniques of culturing krill in large number is thought to be a major break through for further understanding of krill biology. However, these achievements are not effectively gathered to provide a standard methodology. The aim of the workshop is to share the knowledge to date about the methodology of krill culturing and experiments, and contribute to the future experimental studies on Antarctic krill.

Four Japanese krill fishing vessels operated in Area 48 during the 1999/2000 split year. In Subarea 48.1, the operation started in December and lasted until June. In Subarea 48.2, operation took place in December, March, and May to June. In subarea 48.3, operation took place only in June. Trawling positions, CPUEs and body length of Antarctic krill during the period is described. The krill length frequency distribution was further compared with those obtained by the CCAMLR international observer undertaken at the same time, and they resulted in good agreements. The discussion was extended to the possibility of intra-annual variability of two krill stocks (Antarctic Peninsula and Weddell Sea stocks).

Inter- and intra-annual variability of commercial krill trawling positions for the 1980/81 to 1999/2000 seasons in the area to the north of South Shetland Islands were analyzed in relation to biological and environmental factors. Commercial fishing perations concentrated on the outer shelf in the early 1980’s, along the shelf slope in the mid- to late 1980’s, and were highly variable, from the shelf across to the outer shelf in the early to late 1990’s. Intra-annual variation of trawling positions showed a general pattern starting from the outer shelf, and proceeded towards the shelf later in the season. Trawling positions seemed to be primarily governed by the distribution of larger mature krill, especially at the beginning of the operation each season. In summer, biological factors that affect product quality such as salp abundance and the proportion of green krill , also seemed to have an increasing effect on trawling positions.. Ice conditions for the recent fishing period were also demonstrated to have an effect.

There are two general kinds of polynya (an ice-free area within sea ice borders), coastal polynya and open ocean polynya, in the Southern Ocean. Polynya accelerates oceanic and atmospheric processes by exposing the surface of ocean to the atmosphere. Additionally, we think that the coastal polynyas influence biological activity in the winter and spring season. However, there are no minute reports on the place, time and shape of the coastal polynyas. Accordingly, we pursued the transition of the coastal polynyas using satellite image data of sea ice concentrations by the NSIDC (National Snow and Ice Data Center, USA).
Time series of polynyas extent per a day were calculated from 1978 to 1998 and converted into the yearly mean. The time series of the yearly mean in the whole Antarctic Ocean are trending upper after the latter half of the 1980s. The time series around the Antarctic Peninsula are trending like a pulse wave. In the whole Antarctic Ocean, peak years of polynyas extent are in the 1981/82 (from July 1981 to June 1982), 1991/92 and 1995/96. In the Antarctic Peninsula area, peak years are in 1980/81, 1987/88 and 1992/93.

The austral summer 2000/01 marked the fourth full season of land-based predator research at Cape Shirreff, Livingston Island, Antarctica. Results of the monitoring activities undertaken in support of CCAMLR WG-EMM, are summarized in the report