MEPS 457:139-150 (2012)  -  DOI: https://doi.org/10.3354/meps09692

Spatiotemporal associations between Pacific herring spawn and surf scoter spring migration: evaluating a ‘silver wave’ hypothesis

Erika K. Lok1,6,*, Daniel Esler1, John Y. Takekawa2, Susan W. De La Cruz2, W. Sean Boyd3, David R. Nysewander4, Joseph R. Evenson4, David H. Ward5

1Centre for Wildlife Ecology, Simon Fraser University, 5421 Robertson Road, Delta, British Columbia V4K 3N2, Canada
2U.S. Geological Survey, Western Ecological Research Center, San Francisco Bay Estuary Field Station, 505 Azuar Drive, Vallejo, California 94592, USA
3Environment Canada, Pacific and Yukon Region, 5421 Robertson Road, Delta, British Columbia V4K 3N2, Canada
4Washington Department of Fish and Wildlife, 600 Capitol Way North, Olympia, Washington 98501, USA
5U.S. Geological Survey, Alaska Science Center, 4210 University Dr., Anchorage, Alaska 99508, USA
6Present address: Environment Canada, Pacific and Yukon Region, 5421 Robertson Road, Delta, British Columbia V4K 3N2, Canada

ABSTRACT: Surf scoters Melanitta perspicillata are sea ducks that aggregate at spawning events of Pacific herring Clupea pallasi and forage on the eggs, which are deposited in abundance during spring at discrete sites. We evaluated whether migrating scoters followed a ‘silver wave’ of resource availability, analogous to the ‘green wave’ of high-quality foraging conditions that herbivorous waterfowl follow during spring migration. We confirmed that herring spawning activity began later in the year at higher latitudes, creating a northward-progressing wave of short-term localized food availability. Using satellite telemetry and aerial surveys, we documented the chronology of scoter spring migration and the use of stopover locations in relation to herring spawn timing and locations. We found that the migration chronology paralleled the northward progression of herring spawning events. Although there was considerable variability in the timing of both scoter migration and the initiation of herring spawning, the processes were related beyond a coincidental northward progression. During migration, 60% of the tracked scoters visited at least 1 spawn site, and those that used spawn sites were located on spawn sites for approximately one-third of their migration locations. Surf scoters showed close spatiotemporal associations with herring spawning events, confirming that the presence of herring spawn was a factor determining habitat use for many individuals. Surf scoters showed close spatiotemporal associations with herring spawning events, confirming that the presence of herring spawn was a factor determining habitat use for many individuals, a conclusion that is consistent with previous studies which used physiologically based metrics to evaluate the importance of herring spawn.


KEY WORDS: Habitat use · Herring spawn · Melanitta perspicillata · Migration · Satellite telemetry · Surf scoter


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Cite this article as: Lok EK, Esler D, Takekawa JY, De La Cruz SW and others (2012) Spatiotemporal associations between Pacific herring spawn and surf scoter spring migration: evaluating a ‘silver wave’ hypothesis. Mar Ecol Prog Ser 457:139-150. https://doi.org/10.3354/meps09692

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