Interannual site fidelity of Pacific halibut: potential utility of protected areas for management of a migratory demersal fish

Abstract

Abstract Pacific halibut is a large-bodied demersal fish species known to undertake large-scale winter spawning migrations. We characterized annual movement patterns of Pacific halibut relative to a Marine Protected Area (MPA) in Glacier Bay National Park, Alaska using electronic tags. In the summer of 2013, we deployed 25 Pop-up Satellite Archival Tags (PSATs) on halibut to determine seasonal movement patterns, where residency within the MPA was inferred by comparing PSAT depth and temperature records to stationary archival tag data and oceanographic survey data. To characterize within-summer movement patterns, 15 halibut tagged with PSATs were double-tagged with acoustic transmitters and actively tracked during the summers of 2013 and 2014. Home range behaviour and interannual site fidelity at spatial scales <5 km were observed for the majority of tagged fish. A small proportion (6/21 fish with PSAT data) departed the MPA on winter migrations during December 2013. A majority (4/6) of migratory fish returned to the MPA after an average of 57 d (s.d. 22 d) spent outside of the MPA. Migration timing generally coincided with existing winter commercial fishery closures. The annual movement patterns of tagged halibut relative to MPA boundaries and winter commercial fisheries closures suggest that the Glacier Bay MPA could serve as a year-round refuge from commercial harvest for both residential and migratory halibut. If halibut behaviour is similar in other areas, protected areas may provide some utility for management despite the migratory nature of halibut.