Northwest Fisheries Science Center

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Document Type: Contract Report
Center: NWFSC
Document ID: 8867
Title: Demersal fishes and benthic invertebrates off Tillamook Bay, Oregon in July 1985
Author/Editor: Robert L. Emmett, Travis C. Coley, George T. McCabe, Robert J. McConnell
Publication Year: 1988
Publisher: National Marine Fisheries Service
Contracting Agency: U.S. Army Corps of Engineers. Portland, Oregon

In July 1984, the National Marine Fisheries Service entered into a cooperative agreement with the U.S. Army Corps of Engineers to study fish and benthic invertebrate communities of four offshore interim dredge disposal sites.  This information was needed for an application to obtain final designation of interim disposal sites by the Environmental Protection Agency.  Results of the 1984 study showed that benthic invertebrate populations in the area off Tillamook Bay, Oregon, were significantly higher than in similar offshore areas.

The Tillamook Bay interim disposal site last received dredge spoils in 1977, when the Tillamook Bay bar sediments were deposited there.  The present study was initiated in July 1985 to sample benthic invertebrates and demersal fishes off Tillamook Bay in summer, a season not sampled during previous surveys.

The three surveys we conducted near Tillamook Bay in summer 1987 and in fall and winter 1984 indicated that densities of fishes, crabs, and benthic invertebrates increased from summer to fall and decreased in winter.  Recruitment by O. fusiformis in summer was largely responsible for the large numbers of benthic invertebrates found in fall off Tillamook Bay.  These high densities of benthic invertebrates probably occur annually.