An Assessment of the Responses of Rockfish Populations to Rockfish Conservation Area Closures in the Cordell Bank and Gulf of the Farallones National Marine Sanctuaries

Large swaths of the seafloor off the U.S. West Coast have been closed to fishing for bottom fishes —to rebuild overfished stocks, such as bocaccio, canary rockfish, cowcod and darkblotched rockfish. This project will assess how fish populations within Rockfish Conservation Areas (RCAs) off Central California have responded since the closures went into effect in 2002. Teams of volunteer anglers are key to the project, as they are boarding charted passenger sport fishing vessels to help scientists conduct repeat hook-and-line surveys of four sites—two within the RCAs and two outside them. On these rigorously designed “fishing trips,” fish are being caught, measured, tagged and released (for a recapture study later). To the extent possible, the sampling methods and subsequent data analysis will replicate a similar angler survey program led by the California Department of Fish and Wildlife from 1987 to 1998. The primary goals of the project are to compare catch rates, species composition and fish sizes inside and outside the RCAs before and after the closures, as well as patterns that may be more likely attributable to shifts in ocean climate. These climatic factors could favor one species over another irrespective of fishing pressure. In addition to the angler surveys, scientists will collect female rockfishes (from six species) during the winter spawning season to document relationships between female rockfish fecundity and body size, age, liver weight and lipid stores. This component of the project is a collaboration with NOAA’s Cooperative Research Program. The scientists will be analyzing data in the coming months and plan to have some results in early 2014.

Attachments