Humpback whale (Megaptera novaeangliae) entanglement in fishing gear in northern southeastern Alaska

Abstract

The prevalence of non-lethal entanglements of humpback whales (Megaptera novaeangliae) in fishing gear in northern southeastern Alaska (SEAK) was quantified using a scar-based method. The percentage of whales assessed to have been entangled ranged from 52% (minimal estimate) to 71% (conditional estimate) to 78% (maximal estimate). The conditional estimate is recommended because it is based solely on unambiguous scars. Eight percent of the whales in Glacier Bay/Icy Strait acquired new entanglement scars between years, although the sample size was small. Calves were less likely to have entanglement scars than older whales and males may be at higher risk than females. The temporal and spatial distribution of commercial fisheries is complex and difficult to correlate with these results. The percentage of whales with entanglement scarring is comparable to the Gulf of Maine where entanglement is a substantial management concern. Consequently, SEAK humpback whale-fisheries interactions may warrant a similar level of scrutiny.