Southwest Regional Initiative: Southern California Bight Habitat Assessment

NOAAs Southwest Fisheries Region and Science Center have developed an initiative to assess deepwater seafloor communities in the Southern California Bight (SCB). Offshore habitats in the SCB include rocky banks, seamounts, basins, and submarine canyons that span about 75,000 km² and are influenced by a dynamic mixture of cold nutrient-rich water from the California Current and warm oligotrophic water from the south. Complexity in both oceanographic and topographic aspects of SBC habitats promotes highly diverse assemblages of demersal organisms, some of which are overfished rockfishes, ESA-listed white abalone, and dense stands of corals and sponges.

Waters of the SCB have been intensively fished both commercially and recreationally to depths over 300 m for over 40 years. In an effort to protect these valuable resources, large conservation areas and habitat areas of particular concern have been established, including Cowcod Conservation Areas where bottom-contact fishing has been banned for a decade. Through this initiative, the response of deepwater demersal communities following the elimination of fishing impacts will be evaluated.

The goal of this initiative is to evaluate change in biodiversity, abundance, and size composition of demersal stocks and their habitats following the closure of selected areas of the SCB to bottom-contact fishing. A variety of advanced survey tools and approaches are being used to improve assessments of these organisms and habitats. The Regional Office will use this improved assessment information in consultation and in recovery efforts for white abalone and tailor management measures for other demersal species that meet NMFS conservation mandates more efficiently.

Specific objectives are to (1) integrate existing geo-referenced information on seafloor habitats, associated groundfish species, deepsea corals and sponges, and environmental variables into a comprehensive database; (2) develop habitat-specific models to predict distribution and abundance of demersal species; (3) produce maps of predicted occurrence of important demersal species; and (4) establish survey methodologies to improve habitat and stock assessments and to evaluate the benefits of existing  marine protected areas.

This study will significantly enhance our understanding of the effectiveness of habitat conservation measures on rebuilding commercially valuable fish stocks and on the demersal communities of which they are a part.  This information will help NMFS tailor management measures that meet its conservation mandates more efficiently. Both regionally and nationally, this study will provide information on the response of demersal habitats and fish stocks to the removal of fishing impacts on seafloor communities.