CCAMLR

Summary information on CCAMLR fisheries of relevance to the work of WG-FSA is presented. Additional fishery-related information can be found in WG-FSA-03/7 (survey database), 03/63, 03/64 and 03/65 (summaries of observer data), SC-CAMLR-XXII/BG/1 (catches in the Convention Area) SC-CAMLR-XXII/BG/9 (summary of notification for new and exploratory fisheries), SCIC-03/5 (estimates of IUU catches) and CCAMLR-XXII/BG/8 (implementation of conservation measures).

Published references to work on mackerel icefish are listed in alphabetical order of author. This listing was originally tabled at WAMI associated with WG-FSA 2001 and has been updated since that time.

Information on mackerel icefish that has been presented at WG-FSA is summarised and the information augmented by reference to published papers.

A suite of CEMP and non-CEMP parameters collected at Admiralty Bay and Cape Shirreff, South Shetland Islands, Antarctica were analysed to assess the characteristics of the individual parameters, and their relationships to krill abundance and ice cover indices for the period 1978-2003. Results of the analyses are presented in a series of 6 Tables, following the outline of a Draft paper by K.Reid for similar analyses at South Georgia. The tabular data include:
1. Table 1. A list of the penguin performance indices collected at the two sites
2. Table 2. Data on annual variability in krill biomass density, annual sea ice cover and the relationship between these two measures for the period 1992-2002.
3. Table 3. Characteristics of the predator performance indices.
4. Table 4. A linear regression of the relationships between predator indices and ice cover
5. Table 5. The relationships between predator indices and krill biomass presented as a linear regression for both Admiralty Bay and Cape Shirreff and as an exponential regression for the longer Admiralty Bay time series data.
6. Table 6. A summary of the R2 values for all indices by seasons and species

Age, growth rate and age composition of icefish catches in subareas 48.3, 48.2, 48.1 were studied for different periods. The analysis of age composition of icefish in subarea 48.3 showed that the catches consisted mainly of individuals of 2-4 age groups, where more than 60% were represented by fish of two contiguous age groups. It was shown that in the 1980s during a number of years the catches were based on fish of two contiguous year classes, strong 1984 year class and middle 1983 year class. These year classes appeared against a background of the intensive icefish fishery, and krill biomass, judging from the catches, was rather low. Possibly, the abundance of one or another icefish year class in subarea 48.3 depends on many factors, among which it it difficult to determine the most important factors now. A comparative analysis of icefish growth in subarea 48.3 based on data collected in different periods of fishery revealed a substantial interannual variability. The comparison of the growth rate of fish caught in 1978 in subareas 48.3 and 48.2 and that of fish caught in 1986 in subareas 48.3 and 48.1 did not reveal any significant differences. The relatively high growth rate of icefish in subareas 48.3 and 48.2 in 1978 compared with 1985 may indicate on the common factors affected the icefish growth in different regions of the South Atlantic in that time.

The 2002-03 breeding season in comparison with 2000-01 at Edmondson Point was characterised by unusual sea ice and weather condition. Strong southerly winds and snow were experienced at the colony during December coinciding with hatching and the guard stage. The sea ice in the Ross Sea was held in by the presence of the large icebergs. This resulted in extensive sea ice lasting into February adjacent to the Edmonson Point colony. These environmental effects were accompanied by changes in CEMP parameters A2, A6, A9. Breeding success was reduced to 0.3 chicks creched per nest with eggs. The mean crèche date was extended by 4 days, the first incubation shift was significantly longer with respect to 2000-01 (19 days compared with 13). We suggest a combination of environmental factors operating at different times throughout the breeding season were responsible for the poor breeding success. These findings highlight the need for collecting environmental data as part of monitoring for CEMP.