Current Status of Accomplishment or Milestone: Publication is
available.
NOAA-TM NMFS-SWFSC-245. 52 p.
Background: Characterizations of benthic fish habitat and coastal ocean circulation patterns are critical steps in evaluating the effectiveness of reserves at protecting and enhancing coastal fishery resources. From our previous research, different species exhibit affinities for specific benthic habitats. Diversity, quality, and extent of habitat likely are among the most significant determinants of distribution of many benthic fishes. In addition, small-scale oceanographic processes associated with regional wind and ocean current patterns can affect distribution, transport, and survival of young fishes.
Purpose of Activity/Goal of Project: This study had two objectives: 1) to characterize the seafloor within Big Creek Ecological Reserve (BCER) and unprotected adjacent areas, using side scan sonar and bathymetry to map bottom types and quantify potential fish habitats; 2) to characterize patterns of nearshore ocean circulation from hydrographic and Acoustic Doppler Current Profiler (ADCP) data.
Description of Accomplishment and Significant Results: With the coordinated efforts of geologists, biologists, and physical oceanographers, geophysical and oceanographic data were collected during 4 days onboard the NOAA ship McArthur. From maps of bottom types we quantified eight types of benthic habitats, ranging from ripple fields with low relief to extensive rock outcrops and isolated pinnacles. About eight percent of the survey area was made up of complex rock bottom types of high relief; these are suitable habitats for many benthic fish species.
We also characterized patterns of ocean circulation over the continental shelf and upper slope. Upwelling and substantial offshore transport were evident in temperature, salinity, and current data collected at sea and in satellite sea surface temperature imagery. Counter to the traditional view of a southward flowing current over the shelf, we found a coherent 10-20 km-wide current flowing northward at a rate of 8-15 cm/sec through BCER and extending from the surface to 200 m.
Significance of Accomplishment (e.g., to the Center, to Management, and to NMFS Strategic Plan Goals): Our study directly addresses research priorities identified by NMFS Science Board, such as formation of a research agenda for essential fish habitat, studies on the use of refugia as a fisheries management tool, and improving stock assessments by including habitat-specific estimates of species abundances. Our results on habitats in deep water will be especially useful in fulfilling Essential Fish Habitat requirements to amend fishery management plans. Our study is a first step in evaluating a reserve's effectiveness at maintaining and enhancing coastal fish populations, and should generally improve the conceptual design and models for fishery reserves. We are continuing these efforts with funding from NMFS-SWFSC to conduct surveys of ocean currents in different seasons and from CA Sea Grant and CDFG to describe fish and habitat associations within the BCER area.
Problems: None. The efforts of Roy Allen in publishing the Tech Memo are greatly appreciated.
Key Contact: Mary Yoklavich (831-648-9036)