What they learn helps them determine sustainable fishery harvest levels.
NOAA scientists conduct groundfish and crab surveys annually in the Eastern Bering Sea continental shelf from May through July, and biennially in the eastern Bering Sea upper continental slope from May through August, and the Aleutian Islands, from June through August.
The midwater survey, from June through August, focuses mainly on walleye Pollock. It is conducted biennially on the Eastern Bering Sea shelf and typically extends into Russian waters.
Doug DeMaster, science and research director of the Alaska Fisheries Science Center, noted that understanding how well fish stocks are doing is critical because fishermen and managers rely on such data to set sustainable annual fishing quotas.
During surveys, NOAA scientists sort, weigh and count species collected by each trawl, with an emphasis on biological data for target species. They will also collect specimens and data on a variety of species, as requested by cooperating scientists, agencies and institutions.
NOAA officials also said that information collected as part of these surveys, as well as other available data on oceanographic conditions fisheries and protected species, are integrated to provide a more comprehensive understanding of how marine ecosystems are affected. The Eastern Bering Sea groundfish, and crab shelf survey, for example, is a collaborative effort between NOAA and the Alaska Department of Fish and Game. Should a trawl bring in rare fishes and invertebrates, scientists would collect and preserve them.
For four decades, NOAA Fisheries has conducted annual bottom trawl surveys of the continental shelf and Eastern Bering Sea. Their focus species include walleye Pollock, Pacific cod, Greenland Turbot, yellowfin sole, northern rock sole, red king , snow, and Tanner crab.