Distribution and habitat use by endangered Cook Inlet beluga whales: Patterns observed during a photo‐identification study, 2005–2017

Abstract

Abstract Cook Inlet beluga whales (CIBWs; Delphinapterus leucas), are an isolated and declining endangered population in Alaska, USA. Their critical habitat has been broadly defined, with little empirical data on habitat use to direct management actions. This article examines data collected during surveys for a long‐term photo‐ID study to gain insight into the use of critical habitat by CIBW groups and individuals, with a focus on areas where belugas were observed feeding, calving, rearing young, and in transit. It also describes patterns of group distribution, size, and composition, according to sex and age class, in order to better understand how CIBWs are distributed throughout critical habitat during the ice‐free season. The results are presented according to survey month and survey zone, so that patterns of habitat use are accessible in a useful format to aid managers in evaluations of how timing and location of human activities occurring in CIBW critical habitat may overlap with CIBW occurrence and use of these areas. There were 575 beluga groups encountered during 477 photo‐ID surveys conducted in CIBW critical habitat 2005–2017. CIBW locations were mapped, and models were developed to test for temporal and spatial patterns. Approximately 400 individual whales were identified, and their sighting histories were compiled to examine residency and movement patterns. CIBWs were found seasonally in distinct areas, where they aggregate in large groups of both sexes and all age classes while rearing calves and feeding. These areas, and the general corridors connecting them, represent important beluga habitat that warrant focused management attention and protection efforts. Whales travelling among distinct areas of Cook Inlet increase their likelihood of exposure to multiple, localized threats. Habitat protection and the regulation of anthropogenic activities should consider cumulative effects of all activities in the range of CIBWs and their potential to affect the entire population.