The Northern Extent of Pacific White-Sided Dolphin (Lagenorhynchus obliquidens) Distribution in the Eastern North Pacific

Abstract

We present updated distribution information for the Pacific White-sided Dolphin (Lagenorhynchus obliquidens, PWSD) in the southeastern Bering Sea, including Bristol Bay. The northern extent of this dolphin's range currently includes Bristol Bay and a 150-km swath north of the Aleutian Island chain, and presence in the Bering Sea has been described as rare. Our review of National Marine Fisheries Service marine mammal survey data (1991 to 2010) and sighting reports from sources such as the Platforms of Opportunity Program, whaling and fisheries catch records, and naturalist reports (1975 to 2016) found numerous sightings (n = 191) and year-round presence within the current range. We also found 18 sightings, 2 of which were bycatch in commercial fisheries, that occurred north of the existing range and in all seasons. Based on these results, we suggest PWSD presence in the Bering Sea is not rare, occurs year-round, extends farther north than shown on current range maps, and that site-fidelity may occur in areas near and within Bristol Bay.