Surveying Pacific Cod Populations
Scientists conduct bottom trawl surveys in the Gulf of Alaska and Bering Sea/Aleutian Islands and use the resulting information to evaluate the abundance, distribution, and biological condition of cod and other groundfish stocks. We analyze and present these data in scientific reports and stock assessments provided to the Pacific Fishery Management Council, the North Pacific Fishery Management Council, international fishery management organizations, the fishing industry, and the general public. The information we provide is used to set sustainable fishing limits for Pacific cod.
Early Life Studies
We study how young Pacific cod interact with their environment to increase our understanding of and ability to predict how populations may respond to climate. Data are collected through plankton and beach seine surveys and laboratory experiments. Survey data are reported in documents provided to the North Pacific Fishery Management Council.
Age and Growth
We determine the age of individual fish to provide data for age-structured modeling of Pacific cod populations and continue to develop new techniques to accurately age Pacific cod. Other recent research includes a study that looked at Pacific cod life history over the past 200 years based on ear bones (otoliths) found in piles of fish bones and shells discarded by Alaska Natives.
We collect the stomachs of Pacific cod both from both research surveys and from fishing vessels via fisheries observers; identify key prey items including crabs, walleye pollock, and octopus; and measure cod feeding rates over time. This allows us to measure how changes in prey supply affect the health of Pacific cod populations.
An Ecosystem Approach
Our research looks at how environmental changes affect growth, survival, and recruitment (the number of fish that survive to a size available to the fishery) of Pacific cod at all life stages to improve the precision and accuracy of stock assessments and forecasts. Scientific observers working aboard commercial fishing vessels closely monitor catch and bycatch to help gauge possible impacts of humans and the fishery on the ecosystem. Our scientists work closely with industry and managers to evaluate potential adverse fishing impacts through a variety of conservation and management measures.
Each year, a comprehensive ecosystem status report on climate and fishing is compiled in Ecosystem Assessments and Report Cards. These reports are an important step towards achieving the ecosystem-based management goals of the North Pacific Fishery Management Council: to maintain predator-prey relationships, diversity, and habitat, and to monitor effects of climate change.
Assessing Past, Present, and Future Pacific Cod Stocks
We create Stock Assessment and Fishery Evaluation (SAFE) reports to summarize the best available scientific information concerning the past, present, and possible future condition of stocks, marine ecosystems, and fisheries that are managed under Federal regulation, including the Pacific cod fishery. These reports provide information to the North Pacific Fishery Management Council for determining annual harvest levels from each stock; documenting significant trends or changes in the resource, marine ecosystems, and fishery over time; and assessing the relative success of existing state and Federal fishery management programs.
- Grant Thompson, Status of Stocks and Multispecies Assessment Program, Resource Ecology and Fisheries Management