High‐frequency aerial surveys inform the seasonal distribution of Cook Inlet beluga whales

Abstract

ABSTRACTManagement options to mitigate potential effects from the overlap of anthropogenic and marine mammal activities require understanding of species’ habitat use and movement patterns. We analyzed high temporal frequency industrial marine mammal monitoring program aerial surveys conducted over a protracted period from April to October of 2013 and 2014 to examine beluga whale (Delphinapterus leucas) ecology in the Cook Inlet, Alaska, USA. Our objectives were to characterize the spatiotemporal whale distributions, determine the utility of these patterns to inform management practices, and assess industrial survey data as a supplement to agency population monitoring programs. Cook Inlet beluga whale densities peaked in late June to early July, with some activity observed in all survey months. Consistent trends in spatial persistence were identified and found to be associated with the seasonal sequence of prey field distributions including eulachon (Thaleichthys pacificus), Pacific salmon (Oncorhynchus spp.), and gadids (Gadidae spp.). Seasonal beluga whale distributions were stable across both study years, indicating hotspots of habitat use with predictable seasonal timing. The regular temporal and spatial distribution of beluga whale activity suggests potential to inform management efforts to mitigate disturbance of whales from anthropogenic activities in the Inlet. We found high‐frequency surveys conducted as part of industrial marine mammal monitoring programs provided a useful additional data source for population monitoring; however, improvements in survey design and efforts to control for observer detection biases may further increase the utility of these surveys to complement ongoing standardized scientific surveys. © 2018 The Wildlife Society.