Harbor Seals

Justification and Issues:

Harbor seals (Phoca vitulina) are one of the more common, conspicuous, and valued marine mammals that occupy nearshore habitats in the Gulf of Alaska. They are most frequently observed hauled-out on beaches or intertidal platforms during periods of low tide. Because they rely almost exclusively on marine and anadromous fishes as prey, they are generally recognized as occupying an upper trophic position in the nearshore forage fish based food web. They are also one of the preferred prey items of the transient, or mammal eating killer whale (Orcinus orca) type. Because they are thought to respond to changes in forage fish populations, they may serve as indicators of status and change within the marine nearshore forage fish based food web in the Gulf of Alaska. Harbor seals also are an important resource for Alaska Natives and for the tourism industry. Because this species has suffered serious declines in abundance across the Aleutian Archipelago, the Alaska Peninsula to Prince William Sound over the past several decades; populations in the Gulf of Alaska are of particular concern to management agencies.

Status of Monitoring

Although observations of harbor seals in the water and on haul outs are included during the shoreline surveys of marine birds and mammals under the SWAN Nearshore Monitoring Project, this species is most amenable to survey methods that count seals systematically on traditional hauls outs during periods of low tide. The Polar Ecosystems Program (PEP) at the National Marine Fisheries Service-National Marine Mammal Laboratory (NMFS-NMML)conducts such aerial counts of harbor seal haulouts in each of five survey regions along Alaska’s marine coastlines once every 5 years to monitor trends in seal distribution and abundance. The Gulf of Alaska Survey Region, which contains marine coastlines of SWAN parks, was last surveyed during 2006. PEP is currently developing a database containing its aerial survey data. SWAN will rely primarily on these data for monitoring trends in harbor seals along KATM, KEFJ, and LACL coastlines, supplemented by seasonal surveys of harbor seals conducted by the Alaska Sealife Center within KEFJ.