Variability in the Depth Distribution of Salmon Sharks

The salmon shark, Lamna ditropis, is an endothermic, apex predator in the productive waters of the North Pacific. To understand their role in these productive habitats and to identify and better understand their interactions with commercially important species and fisheries, detailed information regarding the distribution of the salmon shark is required. Archival data records from pop-up archival transmitting (PAT) tags were analyzed to examine the geographic and vertical distribution of female salmon sharks and elucidate how their distribution changes in relation to the biotic and abiotic environment. Salmon sharks exhibited a diel periodicity in their dive behavior, and their depth distribution varied spatially and seasonally.  These shifts in depth distribution likely reflected changes in their foraging ecology in response to seasonal and spatial changes in the distribution and availability of important prey. The distribution of salmon sharks appears to follow consistent patterns and has a high degree of geographical and vertical overlap with commercially important prey species. This information increases our understanding of interactions between salmon sharks and commercial fisheries and may assist in fostering responsible management for this species.