Small-scale spatial analysis of subtidal fish guilds and associated habitat characteristics off central California. Jeff M. Field email: JField@mlml.calstate.edu

The scientific party during the 1998 survey of the Big Creek Ecological Reserve. Clockwise from top: Mary Yoklavich, Chris Ijames, Jean deMarignac, Bob Lea, Rick Starr, Jeff Field, Churchill Grimes, Gary Greene, and Dave Slater.

Traditional fishing stocks are decreasing with increasing fishing effort. As a result of these stocks declining, alternative management schemes have been proposed. The Magnuson-Stevens Fishery Conservation and Management Act requires fishery managers to identify and designate Essential Fish Habitat (EFH). EFH for managed species can be designated as no-take marine reserves.

Habitats function as a source of food, refuge from predators, and areas for recruitment and reproduction. To identify and designate EFH, the effects of habitat on fish distribution and abundance must be understood at the appropriate scale. Once specific habitat and fish relationships have been identified, remote-sensing technology can be used to map subtidal areas and designate EFH.

The near-shore environments off California are dominated by rockfishes (Scorpaenidae: Sebastes). Rockfishes are important commercial and recreational fishes. These species are long living fishes, with slow growth rates and late maturity, making them extremely susceptible to over-fishing. Currently, there are strong indications that rockfishes are undergoing high mortality. Rockfishes have a high habitat specificity, which makes these fishes ideal species for protection through designation of EFH.

For this project we surveyed the near-shore (30 to 300 m) waters in the vicinity of the Big Creek Ecological Reserve off central California, to assess the fish guilds associated with distinct habitats. Multivariate techniques are being used to: 1) group fish species and their habitats into guilds; 2) analyze the relationship between selected fish species and distinct habitats at two different scales; and 3) derive an index of habitat electivity for selected fish species