Bronzespotted and Greenspotted Rockfish Assessments Reviewed

On September 22-24 an independent review was conducted for the SWFSC Fisheries Ecology Division’s stock assessments for bronzespotted (Sebastes gilli) and greenspotted (S. chlorostictus) rockfish in California waters. The assessments were written by members of the Groundfish Analysis Team (John Field, Donald Pearson, E.J. Dick, Xi He, and Stephen Ralston) and Senior Scientist Alec MacCall. Reviewers were Mike Prager and Todd Gedamke of the NMFS Southeast Fisheries Science Center and Yan Jiao of CIE–Virginia Tech.

The bronzespotted rockfish assessment differs from most west coast groundfish assessments due to the lack of independent, informative indices of abundance. Insights into population status were largely gained by evaluating the relationship between the bronzespotted rockfish and cowcod (S. levis) fisheries, and using a suite of data-poor modeling methods. It appears that the current abundance of bronzespotted rockfish is well below target levels, most likely about 50 tons or 5% of the historical unfished abundance. Management actions that have been implemented by the Pacific Fishery Management Council since 2000 to protect cowcod and other Southern California rebuilding species (including a specific ban on retaining bronzespotted rockfish based on initial conservation concerns), offer a feasible path to the conservation and rebuilding of this long-lived and low productivity stock.

The greenspotted rockfish assessment was a feasibility study in data-poor methodology using Stock Synthesis 3. Although a moderate amount of length information exists, abundance information is inadequate to support a conventional approach. Numerous simulations of similarly constrained data sets were examined in order to determine potential assessment performance under these limitations. The greenspotted rockfish assessment is still a work in progress, but indications are that abundance is currently between 20 and 35% of the unfished level, and that relative abundance in Southern California is somewhat higher than in Central California waters.

(September 28, 2009)