Aim 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, the number of humpback whales reported to have been entangled in Alaska has increased. In 2003-04 we quantified the prevalence of non-lethal entanglements of humpback whales in northern Southeast Alaska (SEAK) with the ultimate goal of informing management discussions of the entanglement issue for the Central North Pacific stock of humpback whales.Location The near-shore waters of northern Southeast Alaska.Methods We photographed individual humpback whales' caudal peduncles as they dived and then examined the photographs for scars indicative of a previous entanglement. ResultsThe percentage of whales assessed to have been non-lethally entangled at some time in their lives ranged from 52% (minimal estimate) to 71% (conditional estimate) to 78% (maximal estimate). Of these, the conditional estimate is recommended because it is based solely on unambiguous scars. Eight per cent of the whales in one portion of the study area (Glacier Bay/Icy Strait) acquired new entanglement scars between 2003 and 2004, although the sample size was small. Calves were less likely than older whales to have entanglement scars, and males may be at higher risk than females. Whales with more photographs and/or photographic coverage may be more likely to be assessed as having been entangled than whales with fewer photographs and/or coverage.Main conclusions Caudal peduncle scars reveal that the majority of humpback whales in northern SEAK have been entangled. Comparison with statistics on reported entanglements suggests that most whales apparently shed the gear on their own, unless humans are disentangling whales much more often than is reported. While cumulative estimates of the percentage of whales with entanglement scars (e.g. the conditional estimate) provide useful baseline information, future efforts should focus on monitoring the annual rate of entanglement scar acquisition as a more powerful measure of contemporary entanglement rates. Our findings indicate that entanglement of humpback whales in fishing gear in SEAK is a management issue warranting increased attention. A proactive approach is needed to address the problem and to identify and implement preventive measures.

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Humpback whales (Megaptera novaeangliae) are known to interfere with attacking killer whales (Orcinus orca). To investigate why, we reviewed accounts of 115 interactions between them. Humpbacks initiated the majority of interactions (57% vs. 43%; n = 72), although the killer whales were almost exclusively mammal-eating forms (MEKWs, 95%) vs. fish-eaters (5%; n = 108). When MEKWs approached humpbacks (n = 27), they attacked 85% of the time and targeted only calves. When humpbacks approached killer whales (n = 41), 93% were MEKWs, and ≥87% of them were attacking or feeding on prey at the time. When humpbacks interacted with attacking MEKWs, 11% of the prey were humpbacks and 89% comprised 10

, primarily due to longterm site fidelity and local recruitment. We documented sighting histories of >30 yr in southeastern Alaska, for 54 whales, including one 45-yr sighting history. Almost half of the whales first identified as calves returned in subsequent years, at a mean age of 3.2 yr (SE = 0.28, range = 1-17 yr). Over 75% of females had their first calf by age 13. The maximum female reproductive span was 32 yr, and the maximum number of calves was 11. We estimated mean effective calving rate with a simple ratio and used logistic regression to estimate calving probability. Both methods resulted in similar maximal estimates that were somewhat lower than previously published values for this species: 0.324 (95% CL: 0.28-0.36) calvesÁ female has guided Park management actions and documented this once critically endangered population's trajectory toward recovery, often through collaboration with other agencies and organizations, fostering the continued protection and understanding of this distinctive species. Our findings highlight the value of marine protected areas for migratory species with strong seasonal site fidelity and the role of long-term monitoring in interpreting population-level responses to changing marine ecosystems.