Entanglement‐scar acquisition rates and scar frequency for Bering‐Chukchi‐Beaufort Seas bowhead whales using aerial photography

• Published in: Marine Mammal Science
• Main Authors: George, John C. “Craig”, Tudor, Barbara, Givens, Geof H., Mocklin, Julie, Vate Brattström, Linda
• Other Authors: National Marine Fisheries Service, National Oceanic and Atmospheric Administration, U.S. Fish and Wildlife Service
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2019
• Subjects: Balaena mysticetus; Barrow; bowhead whale; Chukchi; Point Barrow; Sea ice; Alaska
• Online Access: http://dx.doi.org/10.1111/mms.12597; https://onlinelibrary.wiley.com/doi/pdf/10.1111/mms.12597; https://onlinelibrary.wiley.com/doi/full-xml/10.1111/mms.12597

Abstract The Bering‐Chukchi‐Beaufort Seas (BCBS) bowhead whale ( Balaena mysticetus ) has been considered at low‐risk for entanglement injuries and ship strikes because their range is mainly north of commercial fisheries; nevertheless, changes to their arctic habitat, including a longer open water period and declining sea ice, have resulted in increasing commercial activity and concern about fisheries interactions. We examined interyear matches (between 1985 and 2011) from a photo identification project and identified whales that had acquired entanglement injuries. We estimated the probability of a bowhead acquiring an entanglement injury using two statistical methods: interval censored survival analysis and a simple binomial model. Both methods give similar results, suggesting a 2.2% (95% CI: 1.1%–3.3%) annual probability of acquiring a scar. We also include an entanglement scar frequency analysis of aerial photographs from the 2011 spring and fall surveys near Point Barrow, Alaska, which suggest 12.4% of live bowheads show evidence of entanglement scarring. Entanglement rates for the BCBS bowhead stock are lower than many other large whale stocks, and abundance has increased over the past 35 yr; however, our findings indicate that fishing gear entanglement is a more serious concern for the BCBS bowhead whale population than previously thought.