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

James R. Lovvorn , University of Wyoming
$49,859

Scoters (Melanitta spp.) are sea ducks that breed in inland wetlands of Canada and Alaska and winter in estuaries and bays on the Pacific and Atlantic Coasts. Like many sea ducks, scoters have declined throughout their Pacific Coast ranges. In Puget Sound, Surf and White-winged Scoters together declined by 57% between 1978-79 and 1992-99; in British Columbia, Surf Scoters have decreased dramatically over the last 50 years. Reasons for these declines remain almost completely unknown due to lack of study.

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.

In the Puget Sound-Georgia Basin, herring spawning grounds are managed as MPAs by regulating habitat loss and harvest of spawn. Local managers recognize that herring spawn is critical to ecosystem function, but data detailing such interactions are lacking. Of particular concern, though studies have shown MPAs are valuable in managing fisheries, the effects of MPAs on marine birds and other animals have received little critical evaluation. Our preliminary telemetry data suggest herring spawning grounds in the Puget Sound-Georgia Basin may be critical links between wintering and breeding areas both for scoters that winter in this region as well as for many thousands of scoters that winter farther south. Thus changes in spawning events in this region are likely to have substantial implications for the effects of these MPAs outside their boundaries. Further, scoters are ideal subjects for such studies because they are widely distributed and depend on food webs similar to those of other marine animals; consequently, Surf Scoters are a targeted indicator of ecosystem health in the Puget Sound-Georgia Basin.

To evaluate the importance of spawning grounds as MPAs for scoters, our objectives are to
1. Estimate fat acquisition by scoters that forage on herring spawn.
2. Evaluate whether herring spawn is a critical supplement to alternative prey.
3. Evaluate how the biomass and extent of spawn affect scoter abundance, and how the duration of spawning events affects their fat acquisition.
4. Estimate the fraction of scoters that winter locally and further south that consume spawn in the Puget Sound-Georgia Basin.
To achieve these objectives, our specific aims are to measure
1. Changes in mass of captured scoters relative to spawning events.
2. The significance of scoter consumption of spawn to fat acquisition, by using stable isotopes and fatty acids to trace the dietary sources of reserves.
3. Depletion of prey alternative to spawn, based on (a) changes of prey density in benthic samples and (b) bioenergetics models that estimate prey consumption by scoters and the ability of alternative prey to meet the scoters’ needs.
4. Shifts in scoter distributions and individual scoter locations relative to spawning events, based on shoreline surveys and VHF and satellite telemetry.

This project will benefit from significant cost share from funded, closely-related investigations by diverse and international collaborators, serving to draw these studies together around issues central to management of marine resources in this region. Concurrent VHF and satellite telemetry will help clarify the seasonal importance of spawn to scoters. Also, we recently began studying the importance to scoters of eelgrass beds, which are managed as MPAs and are vulnerable to anthropogenic change. We will synthesize results of these studies to develop a model of regional scoter habitat requirements. This model will provide an ecological basis for further development of a system of MPAs for herring spawning grounds.

Anderson, E., J. R. Lavvorn, D. Esler, W. S. Boyd, and D. Nysewanser. 2005. The value of herring spawning events to spring conditioning of scoters in the Puget Sound. Georgia Basin. Proceedings of the 2005 Puget Sound Georgia Basin Research Conference, Seattle, Washington. (PDF)

Two manuscripts have been submitted for publication in peer-reviewed journals and more manuscripts are currently in preparation.

Anderson, E. M. , J. R. Lovvorn, D. Esler, W. S. Boyd, D. R. Nysewander, and J. R. Evenson. The value of herring spawning events to spring conditioning of scoters in the Puget Sound Georgia Basin. 2005 Puget Sound Georgia Basin Research Conference, Seattle, WA, March 2005

Anderson, E. M. 2006. Eelgrass, spawn, and scoters: related declines in the Puget Sound-Georgia Basin? 4th Annual ”Wings Over Water” Northwest Birding Festival Semiahmoo, WA, March 2006.

Anderson, E. M. 2006. Seasonal value of eelgrass to scoters: research progress and perspectives. Padilla Bay National Estuarine Research Reserve Mount Vernon, WA. March 2006.

Anderson, E. M. 2005. The value of herring spawning events to spring conditioning of scoters in the PSGB. Second North American Sea Duck Conference Annapolis, MD. November 2005.

Anderson, E. M. 2005. Dietary sources of seasonal scoter reserves: fatty acid analyses. Second North American Sea Duck Conference, Panel Speaker. Annapolis, MD. November 2005

Anderson, E. M. 2005. Declining sea ducks and the role of herring spawning events in the PSGB. Port Townsend Marine Science Center, Guest Lecturer Program Port Townsend, WA. July 2005.

Anderson, E. M. 2005. The value of herring spawning events to spring conditioning of scoters in the PSGB. 3rd Annual ”Wings Over Water” Northwest Birding Festival Semiahmoo, WA. April 2005

Anderson, E. M. 2005. Declining sea ducks and the role of herring spawning events in the PSGB. University of Puget Sound, Science Seminar Series Tacoma, WA. March 2005

Anderson, E. M. 2005. Eelgrass, herring spawn, and scoter declines in the PSGB: a prospectus for study. Padilla Bay National Estuarine Research Reserve Mount Vernon, WA. March 2005.

Anderson, E. M. 2005. Spring conditioning of scoters at herring spawning events: using stable isotopes to evaluate diets of marine birds. Western Washington University, Seabird Ecology Seminar. Bellingham, WA. February 2005.

Anderson, E. M. 2005. Eelgrass, herring spawn, and scoter declines in the PSGB: a prospectus for study. USFWS, Western Washington Fish and Wildlife Office Lacey, WA. January 2005.

Anderson, E. M. 2004. Scoters, eelgrass, and herring spawning events: are the declines related? Western Washington University, Seabird Ecology Seminar Bellingham, WA. February 2004.