CCAMLR

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.

Calculation of age composition of density-at-length data produced during inventory surveys using the method of W.K. de la Mare (1994) is a conventional procedure in the WG-EMM and WG-FSA practice.
Verification of the method was made on the materials on the Baltic cod collected in the ICES Subarea 26. Age-length keys for 1995-2001 and length frequency data obtained during the surveys carried out by research vessels of Russia and other countries were used.
It has been shown that divergence in the estimates of age composition proportions calculated using the CMIX method from those determined from age-length keys (ALK) computed based on the materials of direct age reading may be significant reaching 100 per cent or more. Individually, recruitment estimates also differ considerably from the estimates based on ALK.

Each year, WG-FSA and WG-EMM undertake assessments of stocks and other parameters. The WG-FSA Subgroup on Assessment Methods (WG-FSA-SAM) is to consider the assessment methods to be used by WG-FSA in 2003. This paper aims to summarise the existing assessment process for each species considered by WG-FSA. It concludes with a suggested format for these summaries in the future.

This project involved the large-scale deployment of electronic monitoring (EM) systems on the 2002 British Columbia halibut longline fishery to evaluate the feasibility of EM as an alternative to observer-based at-sea monitoring. EM systems were deployed on 59 regular halibut fishing trips involving 19 fishing vessels, providing about 700 usable sets, 1,000 hours of imagery, and 350,000 observed hooks. Catch items identified by EM represented over 60 fish, invertebrate or seabird species or species groupings, and the 15 fish most abundant species accounted for 98% of the catch. Data from fishing trips where EM and observers were deployed (about 55% of trips) were compared by total overall catch, total catch by set, and catch by individual hook. Overall EM and observer catch estimates agreed within 2%, and individual identifications by hook agreed in over 90% of the catch records. EM reliably (i.e., accuracy within 10%) distinguished thirteen species that represented 97% of the halibut fishery catch. Some species, particularly non-distinct forms, were not identified well by EM. Sample sizes were too small among half the species for determination of an EM species identification capability. Close agreement between EM and observer was also evident with species utilization determination (i.e., kept or discarded) and time, location and depth at set start and finish.
The results of this study demonstrated that EM is a promising tool for at-sea monitoring applications. EM and observer programs differ in many ways in terms of data collection capabilities and program design issues. While the utility of this new technology will depend upon the specific fishery monitoring objectives, the substantially lower cost and broader fleet suitability of EM over observers makes this an attractive option. The authors suggest that a combined EM-based monitoring for the halibut fishery should be continued using two approaches: an integrated EM-observer program using both methods in a complimentary fashion to achieve fleet sampling objectives; and using EM and an electronic fishing log as an at-sea monitoring audit tool. Fruther testing using combined EM and observers on the same trip should occur in the ZN fishery to improve EM rockfish identification capability. The authors also recommend that DFO more comprehensively define the at-sea monitoring objectives of the halibut fishery and strengthen their support for EM-based monitoring approaches to further the development of this technology.

Studies of Patagonian toothfish size composition in fishing area 48.3 were made to determine size at maturity for male and female individuals.A considerable amount of original data indicated that male Patagonian toothfish attained maturity being of a smaller size than female individuals. Half the males became mature when 73-75 cm long, while females matured when 94-96 cm long. Toothfish maturity ogive was drawn and compared with size composition in catches of recent years to show that currently long-line fishery has been taking large amounts of immature and newly matured fish