The role of herring spawning grounds as Marine Protected Areas for scoters (Melanitta spp.) in the Puget Sound-Georgia Basin

Lovvorn, James R.
University of Wyoming, Department of Zoology
Publication Date: 

Scoters and other waterbirds congregate in dramatic numbers to consume Pacific herring (Clupea pallasi) spawn each spring along most of the Pacific Coast. Spawning occurs later at progressively higher latitudes, and may thus provide critical staging areas for scoters acquiring reserves as they migrate north to breed. However, spawning stocks in this region have changed dramatically over time: in Washington State the once largest spawning stock decreased in biomass by 94% over the past 30 years, and in the Strait of Georgia the spatial and temporal extent of spawning has decreased over the past 10-15 years. If herring spawn is an important supplement to alternative prey, these changes in spawning events might have contributed to scoter declines in the Puget Sound-Georgia Basin. However, available data are inadequate to judge whether reduced biomass, spatial extent, and duration of spawning are affecting scoters.