5. Movement Patterns of Spiny Dogfish from Historical Tagging Experiments in Washington State
Ian G. Taylor, Gregory R. Lippert, Vincent F. Gallucci, and Gregory G. Bargmann
Abstract.—The first tagging program for spiny dogfish Squalus acanthias in Washington State was conducted in the early 1940s, coinciding with the period of the highest landings in the history of the fishery, when annual landings in the Northeast Pacific grew to over 50,000 metric tons (mt). A second tagging program in Puget Sound began in 1969, when landings in the Northeast Pacific were below 500 mt. Patterns of recaptures from the two tagging experiments are reanalyzed and compared using a common set of spatial areas for the first time. The fraction of dogfish remaining in each basin and moving between each pair of basins is reported, along with the fraction of dogfish recaptured in Canadian waters. Seasonal movement north and south in coastal waters is considered. Differences in length compositions between inside and outside waters are described, and possible causes of this difference are discussed. The potential use of these tagging results in a population dynamics model is considered.