The International Pacific Halibut Commission (IPHC) and its Staff have reviewed results of the 2002 halibut stock assessment analysis. The resulting Staff recommendations totaling 74.92 million pounds are the same as the catch limits approved by the Commission for the 2002 fishing year. The table on the following page presents the 2002 catch limits and the Staff recommended 2003 catch limits for each regulatory area.

Commercial fishery catch rates in 2002 improved over those of 2001 in Areas 2C and 3A, and were slightly lower in Area 2B. Those in Areas 3B and 4 continued their decline of recent years. While the commercial CPUE in Area 2A rose substantially, the 10-hour derby fishery nature of the commercial harvest and the mixed gear in this area renders CPUE of very limited value as an index of stock abundance. Changes to the IPHC setline survey CPUE in 2002, over values for 2001, were similar to those for commercial CPUE in all areas except Area 2A. In Area 2A, the survey CPUE declined slightly compared with the large increase in commercial CPUE.

The analytic assessment model results for Areas 2B-3A indicate potentially higher biomass in Areas 2C and 3A and slightly lower biomass in Area 2B. However, the progressive application of different ageing methodology (surface vs. break-burn) over the last five years has created a mixture of two different age estimates in the data series. While the Staff has developed a procedure to combine these two types of age estimates for this year’s assessment, we believe this procedure should be improved and may include additional ages obtained by re-ageing previous parts of the data series. This work will be completed over the next year. The second major factor in the change in estimated biomass in these areas is a decrease in survey selectivity/catchability of the oldest fish, that is associated with decreased growth rate of adults. Both this factor and the ageing changes result in a greater estimate of the number of older fish relative to previous assessments.

The preliminary results of the Staff’s investigations into an improved harvest strategy suggest that a conditional constant catch policy will provide greater stability with minimal sacrifice in long-term yield. This policy utilizes caps on harvest rate and total catch, as well as threshold and limit reference points on the biomass, at which the harvest rate would be reduced to protect the stock from ever reaching the lowest observed historical biomass. The Staff is examining several candidate harvest rates and catch limits to determine appropriate recommendations. In addition, the significant decline in growth rate of fish in Area 3A since the mid-1980s may also have generated a change in the sex ratio of the catch because of the relationship of size and selectivity by the fishery. If this is the case, this understanding will need to be incorporated into both the assessment and the investigation of the harvest policy. This work will also be completed over the next year.

The analytic stock assessment has been conducted using several different assumptions concerning selectivity and age composition. The most conservative assumptions indicate greater estimated biomass in Areas 2C and 3A than last year’s assessment and little change in the Area 2B biomass. However, there is some uncertainty as to the appropriate assumptions and it is to this uncertainty that research will be directed during 2003. It is believed that this research will support the higher estimates. However, the investigation of harvest policy may indicate a more conservative approach to catch limit setting in the future, rather than having catch limits tied directly to present-year biomass estimates. These two contrasting elements have led the Staff to recommend that catch limits in 2003 should be the same as those used in 2002, while we complete this research. The Staff believes that maintaining these catch limits is conservative and presents no danger to the stock.

Proposals concerning changes to catch limits should be submitted to the Commission by December 31, 2002. Catch limit proposal forms are available on the Commission’s web page (http://www.iphc.washington.edu) or via fax (206-632-2983) from the Commission office. Additional details about the Annual Meeting can also be found on the web page.