Alaska’s 2018 Summer Fisheries Surveys: What NOAA Measured, Where and Why

Each summer NOAA Fisheries' Alaska Fisheries Science Center sends ships out to measure the fish, crab and other species taken in Alaska's commercial, recreational and subsistence fisheries, and the ocean around them. The data feed stock assessments and ecological studies, and, as the center's deputy director put it, the surveys sample only a tiny fraction of the ocean, yet with statistics they reveal changes across whole ecosystems over time: ecosystems that provide jobs, a stable seafood supply, and a subsistence culture centuries old.

On each survey, scientists sort, weigh and count what each net, line or sonar records, and collect specimens and data requested by other scientists and agencies. On the eastern Bering Sea survey, for example, a sonar on a towed catamaran shows how fish react before they enter the net.

The 2018 season

Most start and end in Dutch Harbor.

Bottom trawl surveys

The Aleutian Islands survey tracks the distribution and abundance of groundfish, crabs and other bottom life, for the region's annual stock assessments and ecosystem models, with partners including the International Pacific Halibut Commission, the University of Washington, NOAA's Northeast Fisheries Science Center and the University of Alaska Fairbanks. Before it ends, both vessels reach Stalemate Bank, in the eastern hemisphere, on the same longitude as New Zealand.

Proposed stations for the Aleutian Islands bottom trawl survey. NOAA Fisheries.

The eastern Bering Sea shelf survey has run every year for 40 years, working west from the eastern end of Bristol Bay. Its focus species: walleye pollock, Pacific cod, Greenland turbot, yellowfin sole, northern rock sole, red king crab, and snow and Tanner crab. Collaborators include the Alaska Department of Fish and Game, the International Pacific Halibut Commission, the University of Washington and the University of Maryland Eastern Shore.

Planned stations on the eastern Bering Sea shelf. NOAA Fisheries.

Pollock by sound

The summer acoustic-trawl survey estimates where walleye pollock are and how many. The 2018 survey was the 21st in a series begun in 1979, now run every two years, with side projects on broadband acoustic classification and acoustic and stereo-camera measurement of individual fish.

Planned transects for the acoustic-trawl pollock survey. NOAA Fisheries.

Plankton, larvae and moorings

• Moorings. NOAA Research and NOAA Fisheries recover and redeploy long-term moorings from the southeastern Bering Sea shelf to St. Matthew Island and beyond, along a transect from about 57°N to 64°N, recording the physical ocean, phytoplankton, zooplankton and marine mammal calls. The spring observations were among the first to document the Bering Sea after the record-low sea ice of winter 2017–2018.
• Larval fish and plankton. Research on how climate variability affects zooplankton and the larvae of pollock, Pacific cod, rock sole and sablefish, to understand and forecast how many young fish survive to join the fishery.

Salmon and forage fish

• Southeast Alaska coastal monitoring, with the Alaska Department of Fish and Game, in its 21st year, samples the upper water column for juvenile salmon and other species. Its data show the effects of temperature and have produced forecasts of the next year's pink salmon returns valued by the seafood industry; new stations in 2018 tested whether it could forecast Chinook returns too.
• BASIS, with NOAA Research, looks at the distribution, size, diet and energy of juvenile pollock, salmon, Pacific cod and forage fish (capelin, eulachon), along with the ocean, plankton and seabirds, and hosts a K-12 teacher through NOAA's Teacher at Sea program.
• The northern Bering Sea surveys, run since 2003 with the Alaska Department of Fish and Game and the U.S. Fish and Wildlife Service, track how the loss of sea ice is changing that ecosystem, with a port call in Nome.

Planned transects for southeast Alaska coastal monitoring. NOAA Fisheries.

The Arctic and the seafloor

Aboard the Coast Guard cutter Healy, NOAA joins a multi-institution team maintaining the Distributed Biological Observatory and other climate observatories in the Chukchi and Beaufort Seas, measuring water and air temperature, sea ice, species abundance, biodiversity and production, with national and international partners and local Native communities.

In the Gulf of Alaska, around Kodiak Island, the NOAA Ship Fairweather maps the seafloor with hydrographic sonar along lines already classed by trawl surveys as trawlable or untrawlable, to build a reliable way of telling the two apart from sonar alone.

Trawlable and untrawlable stations from earlier Gulf of Alaska surveys. NOAA Fisheries.

The center's Marine Mammal Laboratory also planned sixteen field projects on Alaska's marine mammals that year, on their population dynamics, life history, ecology and behavior.

Sources

• NOAA Fisheries, "2018 NOAA Fisheries Summer Surveys to Collect Data Crucial to Manage Alaska Fisheries and Monitor Alaska Marine Ecosystems"; rewritten in hubnx's own words. Maps: NOAA Fisheries.