Research and management of Alaska walleye pollock (Gadus chalcogrammus) stocks is considered to be world-class and an example of how science-based management can ensure sustainability. Scientists at the Alaska Fisheries Science Center collect and analyze the data that managers need to set sustainable catch limits.
Surveying Pollock Populations
We gather information about the number, location, and age of pollock in Alaskan waters during annual surveys using acoustic technology, midwater trawls, and bottom trawls. These data are combined with information collected by fishery observers.
Pollock in the Gulf of Alaska, eastern Bering Sea, and Aleutian Islands are managed as separate stocks based on the results of genetic studies, biological characteristics, and analyses of larval drift patterns from spawning locations.
Early Life Studies
We study factors affecting young pollock survival to recruitment (when they reach a size available to the fishery at around 3 years old). These survival rates can vary dramatically from one year to the next and this affects pollock populations, posing challenges for the fishery and fishery managers. Scientists have linked these ups and downs to variability in environmental conditions during the early life of pollock.
Understanding how young pollock respond to environmental changes helps scientists understand and communicate future uncertainty in population size and hence size of eventual fishing quotas to managers, the public, and fishery stakeholders.
Age and Growth
We determine the age of individual fish to provide data for age-structured modeling of populations and continue to develop new techniques to age walleye pollock.
An Ecosystem Approach
Environmental factors affect walleye pollock populations in the Eastern Bering Sea, Aleutian Islands, and Gulf of Alaska. Prey availability and the number of fish, seabird, and marine mammal predators and their spatial overlap with pollock also have a large impact. Comprehensive scientific observer coverage aboard commercial fishing vessels closely monitors 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 mitigate potential adverse impacts through a variety of conservation and management measures, and by developing appropriate gear modifications.
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 Pollock 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 walleye pollock 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.
- Ecosystem Status Reports
- Recruitment Processes Program
- Fisheries Interaction Team
- Status of Stocks and Multispecies Assessments
- Alaska Groundfish Survey Data Map
- Age and Growth Procedures for Otolith Examination
- Age Reading Interactive Demonstration
- Fish Species Maximum Age Data
- North Pacific Groundfish Stock Assessments
- Groundfish Catch Percentage and Value
- Resource Ecology and Ecosystem Modeling, Number of Stomachs Database
- Alaska Ichthyoplankton Information System Database