In making catch limit recommendations for 2011, staff has considered the results of the 2010 stock assessment, changes in the commercial and survey indices used to monitor the stock, and a harvest policy that reflects coastwide policy goals.
Coastwide commercial fishery weight per unit effort (WPUE) decreased by approximately 6% in 2010 from 2009 values, primarily due to declines ranging from 6-24% in the central and western portions of the stock (Areas 3A to 4). In contrast, commercial WPUE increased substantially in Areas 2A and 2B, and modestly in Area 2C. However, the 2010 IPHC stock assessment survey WPUE values increased only in Areas 2A (109%) and 2B (3%) while decreasing from 5-36% in Areas 2C to 4. The coastwide survey index of abundance declined by approximately 15% from 2009 to 2010.
The staff conducted several analyses in 2010 that have been incorporated into the staff's catch limit recommendations. These included the addition of new Bering Sea survey data into estimation of exploitable biomass, and a statistical analysis resulting in an improved averaging procedure for the survey WPUE data used in apportioning the coastwide biomass estimate into regulatory area biomass estimates. At the request of the Commission, the staff also developed a procedure to directly deduct removals of halibut between 26-32 inches from available yield, in the area of occurrence.
The staff and the Commission have also been concerned that the Commission's Slow Up - Fast Down (SUFD) harvest policy adjustments have not achieved target harvest rate goals in the face of continued stock declines, decreases in halibut growth rate, and the history of high exploitation rates for some areas in recent years. The staff therefore recommends that the SUFD policy be modified to a Slow Up - Full Down (SUFullD) policy, to achieve the necessary reductions in harvest rate and promote increases in exploitable biomass. That is, staff recommendations would incorporate the existing policy of a 33% increase from previous year's catch limits when stock yields are projected to increase but use a 100% decrease in recommended catch, when stock yields are projected to decrease.
Catch Limit Recommendations for 2011
The 2010 stock assessment resulted in a coastwide estimate for the 2011 Fishery Constant Exploitation Yield (FCEY) of 41.89 Mlb, a decline of approximately 6% from the 2010 value of 44.40 Mlb. While FCEY values increased in Areas 2A and 2B, these increases were offset by decreased values for Areas 2C and 3. The 2011 FCEY values for the combined subareas of Area 4 remained largely unchanged. For 2011, the staff has evaluated potential adjustments to the apportionment procedure for the coastwide exploitable biomass. Of the adjustments considered, the staff recommends continued use of the hook competition and survey timing factors. In addition, analysis supports the use of reverse-weighted average survey WPUE as the most appropriate averaging method, which places much higher emphasis on the most recent year's survey WPUE than on those of previous years. For all areas, direct deductions for all bycatch and wastage mortality between 26-32 inches are made in the area of occurrence to determine the FCEY. Previously, the deductions for this mortality were included in calculation of the target harvest rate.
The largest changes in recommended 2011 Catch Limits occur in Areas 2C and 3. For Area 2C the difference in the catch limit recommendation between 2010 and 2011 is primarily the result of the application of the SUFullD harvest adjustment. For Area 3, the primary cause of the change in recommendations between 2010 and 2011 is the estimated decline in exploitable biomass.
The staff recommended Catch Limits totaling 41.02 million pounds for 2011, a decrease of approximately 19% from 2010 Adopted Catch Limits, are presented in Table 1. The Area 2A recommendation includes all removals (commercial, treaty Tribes, and sport) allocated by the Pacific Fishery Management Council's Catch Sharing Plan. Area 4CDE is treated as a single regulatory unit by the Commission, although the North Pacific Fishery Management Council's Catch Sharing Plan allocates the Commission catch limit into limits for the individual regulatory areas. The Area 2B catch limit recommendation includes totals for the commercial and sport fisheries. The Canadian Department of Fisheries and Oceans will allocate the adopted catch limit between the sport and commercial fisheries.
For Areas 2C and 3A the catch limit recommendation includes the use of the North Pacific Fishery Management Council (NPFMC) and National Marine Fisheries Service (NMFS) authorized Guideline Harvest Levels (GHL) for the halibut recreational charter fisheries of 0.788 Mlb and 3.650 Mlb, respectively, as the projected removals by that sector for 2011. The catch limit recommendations are made with the assumption that both Canada and the U.S. will manage to their domestic targets for sport fish.
These recommendations, along with public and industry views on them, will be considered by IPHC Commissioners and their advisors at the IPHC Annual Meeting in Victoria BC, Canada, during January 25-28, 2011. These recommendations are preliminary and, as final data are included in the assessment, may be updated for the Annual Meeting but are not expected to change significantly. Proposals concerning changes to catch limits should be submitted to the Commission by December 31, 2010. Catch limit proposals are available on the Commission's webpage (http://www.iphc.int/meetings-and-events/annual-meeting/catch-limit-comments.html) or from the Commission's office. Additional details about the Annual Meeting can also be found on the web page.
Table 1. IPHC staff recommended catch limits for 2011, by IPHC regulatory area (million lbs, net weight). The 2010 fishery catch limits are included for comparison.
|Regulatory Area||2010 Adopted Fishery Catch Limit||2011 IPHC Staff Recommended Fishery Catch Limit|
a Includes sport, tribal, and commercial fisheries.
b Includes sport and commercial fisheries.
c Individual catch limits for Area 4C, 4D, and 4E are determined by the North Pacific Fishery Management Council catch sharing plan.
Figure 1. International Pacific Halibut Commission Regulatory Areas.