STUDIES IN GROUNDFISH HABITAT

Petre Adams (UCSC)

Link to NOAA Strategic Plan: NOAA's Mission Goal 1: Protect, Restore, and Manage the Use of Coastal and Ocean Resources through Ecosystem-based Management

RESEARCH OBJECTIVES AND SPECIFIC PLANS TO ACHIEVE THEM

The overall goal of this study is to collect information on demography, distribution and abundance of groundfish species and associated complex, high-relief habitats, and to apply the results to the assessment of the status of groundfish stocks off California. Specific objectives are 1) compare and evaluate in situ and traditional extractive assessment methods; 2) survey groundfish populations in complex habitats; 3) evaluate spatial and temporal variability in demography, abundance and distribution; 4) determine association with, and relationships among, seafloor features and biologic components of habitats; 5) characterize associated fish communities; and 6) advance quantitative understanding of species life histories and benthic community structure/dynamics.

RESEARCH ACCOMPLISHMENTS

From visual surveys conducted from a research submersible, we have made significant progress in characterizing the associations of groundfish assemblages with seafloor habitats off California. Small-sized demersal fishes (pygmy and rosy rockfishes, blackeye gobies) accounted for over half of all fishes surveyed over low-relief rock and mud habitats on the continental shelf north of Santa Cruz, CA. A disproportionately higher number of fishes were observed in boulder and cobble habitats while fewer fishes were observed in mud and brachiopod habitats. Most fishes were immature, with size less than that at first maturity for over 50% of the individuals in 18 species.

We characterized habitat requirements of juvenile cowcod (Sebastes levis) on rocky banks and outcrops in deep water (up to 365 m) in southern and central California. This species demonstrated ontogenetic shifts in their habitat associations, with small fish primarily among cobbles or cobbles and small boulders and larger fish in high-relief rock habitats. Our study resulted in a characterization of seafloor habitats on a small spatial scale that is relevant to juvenile cowcod, and clearly demonstrates the value of direct observations of species living over rocky substrata.

We have hired a temporary GIS/Database Technician (Claudia Makeyev) for three months to assist in assembling our historic datasets on seafloor habitats and fish and invertebrate assemblages in deepwater from southern and central California. Claudia is compiling data on marine debris (especially discarded fishing gear) that is associated with these seafloor communities, and will analyze potential impacts of these data to deepwater benthic habitats and fishes.