Maximum age data is from ages generated between 1990 and 2020 except Pacific cod, which is limited to collections read after 2000.

Natural mortality (M) is estimated using the method outlined by Hoenig (1983) which uses maximum age to estimate instantaneous mortality.

The top five maximum ages encountered by the AFSC Age and Growth Program for collections aged between 1990 and 2020 except Pacific cod, which is limited to collections read after 2000.

Aerial surveys of coastal Alaska are the primary method for estimating abundance of harbor seals. A particular challenge associated with aerial surveys of harbor seals is maintaining consistent spatial representation of haulout locations. In some cases, seals aggregate into a single large grouping at a particular area. In other cases, seals aggregate into several smaller groups spread over a particular area. To establish geo-spatial consistency, the Alaska Fisheries Science Center developed coastal survey units (spatial polygons) throughout the distriubtion of harbor seals in Alaska. Each survey unit was designed to be approximately 10-15 kilometers in coastal length, to faciliate efficient aerial surveys, and to aggregate known harbor seal haulout locations. Each survey unit was assigned a unique alphanumeric identifier and the spatial data are provided in the geographic (epsg:4326) coordinate reference system. The survey units form the spatial foundation for estimation of harbor seal abundance and trend.

This dataset contains GIS layers that depict the known spatial distributions (i.e., ranges) of the two subspecies of bearded seals (Erignathus barbatus). It was produced as part of a U.S. Endangered Species Act status review, which included delineating the species in question and assessing its risk of extinction within the foreseeable future throughout all or a significant portion of its range. Its boundaries are based on previously published range maps and/or descriptions of the species' distribution in published or unpublished accounts. All boundaries should be considered approximate. The approximate North American boundary between the two sub-species was changed to 130W (from 112W), based a re-analysis of the genetic data.

This dataset contains GIS layers that depict the known spatial distributions (i.e., ranges) and reported breeding areas of ribbon seals (Histriophoca fasciata). It was produced as part of a U.S. Endangered Species Act status review, which included delineating the species in question and assessing its risk of extinction within the foreseeable future throughout all or a significant portion of its range. Its boundaries are based on previously published range maps and/or descriptions of the species' distribution in published or unpublished accounts. All boundaries should be considered approximate.

This dataset contains GIS layers that depict the known spatial distributions (i.e., ranges) of the five subspecies of ringed seals (Phoca hispida). It was produced as part of a U.S. Endangered Species Act status review, which included delineating the species in question and assessing its risk of extinction within the foreseeable future throughout all or a significant portion of its range. Its boundaries are based on previously published range maps and/or descriptions of the species' distribution in published or unpublished accounts. All boundaries should be considered approximate.

This dataset contains GIS layers that depict the known spatial distributions (i.e., ranges) and reported breeding areas of spotted seals (Phoca largha). It was produced as part of a U.S. Endangered Species Act status review, which included delineating the species in question and assessing its risk of extinction within the foreseeable future throughout all or a significant portion of its range. Its boundaries are based on previously published range maps and/or descriptions of the species' distribution in published or unpublished accounts. All boundaries should be considered approximate.