Modeling of the Spatial Distribution of Spiny Dogfish in the Gulf of AlaskaPublished online on 26. June 2013
Modeling of the Spatial Distribution of Spiny Dogfish (Squalus suckleyi) in the Gulf of Alaska using Generalized Additive and Generalized Linear Models
Jason R Gasper, Gordon H. Kruse
The spiny dogfish (Squalus suckleyi) is a common bycatch species in the Gulf of Alaska. Their spatial distribution is poorly understood, as most catch is discarded at sea. We analyzed dogfish spatial distribution from fishery-dependent and independent observations of longline gear between 1996 and 2008 using generalized additive and generalized linear models. Poisson, negative binomial, and quasi-Poisson error structures were investigated; the quasi-Poisson GAM fit best. Models showed that dogfish catches were concentrated east of Kodiak Island in waters ≤100 m. Results facilitate design of future dogfish assessment surveys, identification of areas in which to focus at-sea observations for fishing mortality estimation, and provide the basis for first-ever designation of dogfish essential fish habitat (EFH), despite U.S. legal requirements for EFH designations since 1996. Identified areas of high bycatch may expedite spatial management by indicating areas in which directed dogfish fisheries could be focused or, conversely, areas in which heightened conservation and catch accounting efforts would be most effective to prevent overfishing of this long-lived, late-maturing species.
Canadian Journal of Fisheries and Aquatic Sciences, 10.1139/cjfas-2012-0535