Coral and juvenile rockfish from Delta submersible.

Juvenile rockfish in sponge from Delta submersible.

Studies on benthic habitat in the MESA program focus on identification of essential fish habitat, determining the effects of fishing on benthic habitat, improving stock assessments, and understanding basic ecological processes and life histories of benthic organisms. Seafloor habitat mapping is increasingly being integrated with these long-term objectives. Large research vessels have collected high resolution bathymetry and backscatter data using multibeam sonar on several areas in the Gulf of Alaska (GOA) and Aleutian Islands. Benthic habitat mapping has important implications for stock assessment. Many stock assessments for groundfish rely on trawl surveys to provide abundance information. In some areas, especially in the Gulf of Alaska and Aleutian Islands, an unknown proportion of the survey area is untrawlable. Since the average density of a particular fish species may differ between trawlable and untrawlable grounds, absolute abundance estimates derived from trawl surveys may be biased. Habitat mapping can help in the computation of the proportion of trawlable ground, which will aid in the calculation of unbiased abundance estimates.

Contact:
Kalei Shotwell
Auke Bay Laboratories
Alaska Fisheries Science Center, NOAA Fisheries

Ted Stevens Marine Research Institute
17109 Pt Lena Loop Rd
Juneau AK 99801
Kalei.Shotwell@noaa.gov