Hi folks,

This seminar will be at the Natural Resources Building (corner of 11th & Washington) in Olympia on the 9th.
Be there or be square.

Jon. Anderson
Olympia, Washington
festuca at olywa.net

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Subject: Next Fish and Wildlife Seminar - Fish Eating birds and Implications for Fisheries Mgmt, Tues Dec 9


>>> 11/24/03 11:40AM >>>

The next Fish and Wildlife Seminar will be Tuesday December 9th in Olympia NRB Room 175, Noon-1:30.

Abundance, Distribution and Consumption of fish by Piscivorous Birds along the Yakima River, Washington State: Implications for Fisheries Management.

Walter Major III
Washington Cooperative Fish and Wildlife Research Unit,
School of Aquatic and Fishery Sciences, University of Washington

Abstract - The abundance and spatial and temporal distributions of piscivorous birds can have significant impacts to the survival of valued fish species in rivers. During 1999-2002, we determined the abundance, distribution and estimated the maximum consumption (kg biomass) of fish-eating birds along the length of the Yakima River in Washington State. Sixteen different species were observed during the 4-yr study, but only half of those were observed during all years. Abundance and estimated consumption of fish within the upper and middle sections of the river were dominated by common mergansers (Mergus merganser), which are known to breed in those reaches. Common mergansers accounted for 78 to 94% of the estimated total fish take during the study period for the upper river or approximately 28,383 ? 1,041 kg over the 4 yrs. A greater diversity of avian piscivores occurred in the lower river and potential impacts to fish populations was more evenly distributed among the species. In 1999-2000, great blue herons potentially accounted for 29 and 36% of the fish consumed, whereas in 2001-2002 American white pelicans accounted for 53 and 55%. We estimated that approximately 75,878 ?6,616 kg of fish were consumed by piscivorous birds in the lower sections of the river during the study. Bird assemblages differed spatially along the river with a greater abundance of colonial nesting species within the lower sections of the river, especially during spring and the nesting season. The abundance of avian piscivores and consumption estimates are discussed within the context of salmonid supplementation efforts on the river and juvenile out-migration.
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