Janet L. Neilson, Christine M. Gabriele, Jan M. Straley, Susan Hills, and Jooke Robbins | 2006 Conference Poster Presentation

Janet L. Neilson^{(1), (2)}, Christine M. Gabriele⁽²⁾, Jan M. Straley⁽³⁾, Susan Hills⁽¹⁾, and Jooke Robbins⁽⁴⁾
1) University of Alaska Fairbanks, School of Fisheries & Ocean Sciences, Fairbanks, AK 99775, USA
2) Glacier Bay National Park & Preserve, P.O. Box 140, Gustavus, AK 99826, USA
3) University of Alaska Southeast, 1332 Seward Avenue, Sitka, AK 99835, USA
4) Provincetown Center for Coastal Studies, 59 Commercial Street, Provincetown, MA 02657, USA

Entanglement in fishing gear is recognized as a potentially significant source of serious injury and mortality for humpback whales (Megaptera novaeangliae) in some parts of their range. In recent years an increasing number of humpback whales have been reported entangled in Alaska. In 2003 and 2004 we conducted the first systematic study of entanglement in northern southeastern Alaska (SEAK), using a scar-based technique developed and ground-truthed in the Gulf of Maine. We photographed the caudal peduncle of unique individuals as they dove and examined them for evidence of wrapping, binding and linear notch scars indicative of a previous entanglement. Whales with more caudal peduncle photographs and/or greater caudal peduncle photographic coverage were more likely to be assessed as having been entangled than whales with fewer photographs and/or coverage. The cumulative percentage of whales assessed to have been entangled ranged from 52% (minimal estimate) to 71% (conditional estimate) to 78% (maximal estimate). We recommend the conditional estimate because it is based solely on whales with unambiguous caudal peduncle scars. Eight percent of the whales in Glacier Bay/Icy Strait that were sampled in both years (n = 26) acquired new entanglement scars between years. Calves were less likely to have entanglement scars than older whales. Males and females did not have significantly different conditional scarring percentages. More females than males had ambiguous scars; however, these results may have been confounded by differences in the number of caudal peduncle photographs available. The percentage of whales with entanglement scarring in northern SEAK is comparable to that reported for one western North Atlantic population (the Gulf of Maine) where entanglement has been identified as a substantial management concern. Consequently, humpback whale-fisheries interactions in SEAK may warrant a similar level of scrutiny.

Humpback Whale Entanglement in Fishing Gear in Northern Southeastern Alaska