Resource Ecology & Fisheries Management  (cont.)

(2001 Stock Asessment Summary: part 6)
BSAI Other Red Rockfish

The other red rockfish complex is composed of northern, sharpchin, rougheye, and shortraker rockfish.  For management purposes, these species are managed in two groups: northern/sharpchin and shortraker/rougheye.  For each species, the FABC  was set at the maximum value allowable under Tier 5, which is 75% of M.  Accepted values for M are rougheye rockfish—0.025, shortraker rockfish—0.030, and northern rockfish—0.060.  Note that values are not given for sharpchin rockfish because they are at the edge of their range and are uncommon in the BSAI.  Multiplying these rates by the best estimates of species-specific biomass gives the following 2002 ABCs:

The 2002 OFL levels relative to 2001 recommendations,
assuming identical species complexes as used in 2001, are as follows:

 
Other Rockfish

Assessment authors conducted a detailed examination of the available information for assessment of the status of the other rockfish complex.  Catch distribution maps were created for the light dusky rockfish and shortspine thornyhead complex.  The list of other rockfish was re-examined to reveal that of the 28 species listed in the 2000 SAFE, only 7 species have been confirmed or tentatively identified in catches from the BSAI.  These seven species include: dark dusky rockfish, light dusky rockfish, harlequin rockfish, red banded rockfish, redstripe rockfish, yelloweye rockfish, and shortspine thornyhead.  No new biomass estimates were available for the 2002 assessment.  Therefore, the recommended ABCs and OFLs for 2002 were set equal to the 2001 values.

 
AI Atka Mackerel

New catch data and 2000 fishery age data were incorporated into the AI Atka mackerel model.  The SSC has determined that this stock is qualified for management under Tier 3 of the BSAI Groundfish FMP.  The updated point estimates of B_40%, F_40%, and F_35% from the present assessment are 124,500 t, 0.34, and 0.39, respectively.  Projected spawning biomass for 2002 is 118,000 t, placing Atka mackerel in sub-tier “b” of Tier 3.  The maximum F_ABC value allowable under Tier 3b is F_40% adjusted (0.32).  Projected harvesting at a fishing mortality rate of 0.32 gives a 2002 catch of 71,300 t, which is the maximum permissible value of ABC under Tier 3b.  The assessment authors recommend setting F_ABC at a value of F_52% (0.21) would give a 2002 catch of 49,000 t.   Short-term projections under an average fishing mortality rate equal to F_52% show that female spawning biomass will increase above the estimated B_40% spawning biomass by 2003.

To apportion ABCs among areas, the authors used a weighted average of the four most recent survey estimates of the distribution of the biomass, which gives the greatest weight to the 2000 survey.  When applied to the recommended ABC of 49,000 t, this formula gives the following subarea-specific ABCs:  Eastern Bering Sea and Eastern Aleutians = 5,500 t (11.2%), Central Aleutians = 23,800 t (48.5%), Western Aleutians  = 19,700 t (40.2%).

The OFL was determined from the Tier 3b formula, where an F_35% adjusted value of 0.37 gives a 2002 OFL of 82,300 t.  Model projections indicate that this stock is neither overfished nor approaching an overfished condition.

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AFSC Quarterly
Research Reports
Oct-Dec 2001