Summer Distribution and Feeding of Spiny Dogfish off the Washington and Oregon Coasts

摘要

Our understanding of the spiny dogfish Squalus acanthias of the northeastern Pacific is based almost exclusively on nearshore populations from enclosed regions (e.g., Strait of Georgia, Hecate Strait, and Puget Sound), with little attention given to more offshore populations along the open coast. Our purpose here was to characterize the summer distribution and diet of dogfish off the Washington and Oregon coasts by means of two fishery surveys: the National Marine Fisheries Service (NMFS) triennial shelf groundfish survey, 1977-2004, and the NMFS/Oregon State University juvenile salmon survey, 1998-2002. Dogfish catches were patchy throughout the entire period and showed a broad distributional range along the Washington and Oregon coasts. The highest abundances occurred in shallow waters (55-184 m) off the northern Washington and central Oregon coasts. Around the Columbia River plume, dogfish catch per unit of effort was significantly related to salinity and surface temperature patterns, but not tochlorophyll concentrations. Dogfish consumed a variety of prey, including both pelagic and benthic taxa, and with increasing size exhibited a shift in their diet to more fish and larger prey overall.