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FOOD WEB LINKS BETWEEN SEABIRDS AND PELAGIC SCHOOLING FISHES IN THE ESTUARY, PLUME, AND NEARSHORE MARINE HABITATS OF THE COLUMBIA RIVER

Released: 2015
Citation:
Zamon, JE, EM Phillips, DD Roby, DE Lyons, K Collis, J Adams. 2015. FOOD WEB LINKS BETWEEN SEABIRDS AND PELAGIC SCHOOLING FISHES IN THE ESTUARY, PLUME, AND NEARSHORE MARINE HABITATS OF THE COLUMBIA RIVER. Pacific Seabird Group, 42nd Annual Meeting, 18-21 February 2015, San Jose, CA. [Oral Presentation]

Recent estuary and ocean research demonstrates that hundreds of thousands of fish-eating birds aggregate in the Columbia River estuary, plume, and adjacent coastal regions of Oregon and Washington during April through September. We synthesized information from existing seabird and fish studies to better understand the food sources supporting seabird assemblages near the Columbia River. Piscivorous species are numerically dominated by common murres (Uria aalge), sooty shearwaters (Puffinus griseus), double-crested cormorants (Phalacrocorax auritus), Brown pelicans (Pelecanus occidentalis), gulls (Larus spp.), and Caspian terns (Hydroprogne caspia), but also include loons, Western grebes, and less common cormorants, alcids, and procellarids. Large tidal exchanges of freshwater and saltwater among the Columbia River Estuary, plume, and nearshore ocean are accompanied by large but poorly understood changes in the species composition and biomass of marine schooling fishes. ESA-listed juvenile Columbia River salmon and eulachon (Thaleicthys pacificus) also occupy the same habitat. Data from multiple studies shows that northern anchovy (Engraulis mordax), whitebait smelt (Allosmerus elongates), Pacific herring (Clupea pallasi), and juvenile Pacific salmon (Oncorhynchus spp.) are probably the key pelagic prey species supporting seabirds in this region. Three fish species are common to both the estuary and ocean: northern anchovy, surf smelt, and Pacific herring; juvenile salmon (primarily O. tshawytscha, O. kisutch, and O. mykiss) are also common in both locations. In contrast, juvenile American shad (Alosa sapidissima) are numerically dominant in the estuary only, whereas whitebait smelt, Pacific sardine (Sardinops sagax), and juvenile Pacific hake (Merluccius productus) are numerically common in the ocean. The food web interactions in this area among seabirds, forage fishes, and ESA-listed anadromous fishes have a number of implications for future management and conservation of marine resources.



This product is associated with the following project:
Common Murre associations with the Columbia River Plume and adjacent waters

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