Work

Anthropogenic activity and Cook Inlet beluga whale presence in two Alaska rivers

Year: 2026

Type: article

Abstract: The endangered Cook Inlet beluga whale (CIB) Delphinapterus leucas inhabits Cook Inlet, Alaska, USA, year-round and shares the waters with numerous sources of anthropogenic activity, including marine traffic, fishing, oil and gas production, military activities, and coastal development. Two Cook Inlet rivers, the Kenai and Kasilof, are historically important summer foraging habitat for CIBs, due to the spawning migration of Pacific salmon Oncorhynchus spp. These rivers are also important for commercial and personal-use fishing, which has led to an increase in anthropogenic activity in recent decades. Previous research suggests that CIB use of this historically important habitat may no longer coincide with peak salmon runs, prey important to the CIB diet. This study aimed to (1) characterize seasonal patterns of CIB presence in the Kenai and Kasilof rivers using passive acoustic monitoring and visual surveys, and (2) assess how CIB presence correlates with anthropogenic activity. From May to November 2021 and 2022, we monitored CIB presence using echolocation loggers (F-PODs), recorded underwater sound with sound recorders (SoundTraps), and conducted visual observations of CIBs and vessel activity. CIB detections in the Kenai River showed a strong seasonal pattern and were lowest during periods of high anthropogenic activity. In contrast, CIBs were not detected in the Kasilof River, though anthropogenic activity was lower than in the Kenai River. Our results indicate that CIB presence in the Kenai River coincided with low anthropogenic activity, despite lower prey availability, suggesting that CIBs may be avoiding the river during periods of high anthropogenic activity.

Source: Endangered Species Research

DOI: 10.3354/esr01509

Authors: Sonia V Kumar, Manuel Castellote, Verena Gill, Curry J Cunningham, Brenda Konar, Lara Horstmann