Recovery plan for the humpback whale (Megaptera novaeangliae)

US National Marine Fisheries Service, Office of Protected Resources, Humpback Whale Recovery Team

General info on humpback whales, incl. population status of whales in US waters, natural history, and impact of acoustic disturbance. Review of other studies. 1. Acoustic disturbance: vessel noise - "Short-term disturbance of hw by vessels has been investigated in Alaska [Baker reports, krieger & Wing) and in Hawaii (Bauer...). Observed responses to vessels included attempts to move away, changes in patterns of breathing and diving, and occasional displays of possibly agonistic behavior. Baker et al (1983 - Impact of vessel traffic on the beh of HW in SE AK) described two responses of whales to vessels: (1)"horizontal avoidance" of vessels 2000 to 4000 m away, characterized by faster swimming with few long dives; and (2) vertical avoidance" of vessels from 0 to 2000 m away, during which whales swam more slowly, but spent more time submerged. Other responses observed, such as trumpeting, or breaching, lobtailing, or flipper slapping may sometimes indicate disturbance, but may also signify general excitability (Baker, Perry & Vequist 1988). The significance of the extra energetic costs incurred by whales responding in these ways is not known. Whales appear to respond less to vessels when actively feeding (BPV 1988) or energetically involve in any other behavior." p. 27 "HW are also known to approach boats. The freqency of with which this behavior is expressed may vary among populations and may change over time as individuals develop learned response to particular vessels or vessel activites. p. 27 "Glockner-Ferrari and Ferrari (1985a) have also reported a change in distribution assoc. w/ increased levels of vessel traffic" in Maui. "Although noise from boats and high-speed thrill craft are a likely causative agent, they point out that pollution and runoff may also be factors" p. 28 2. Acoustic disturb: comm. whale watching & research boats Suggests visual disturbance could be a problem, but usually whales would probably hear a boat before seeing it. Also more of a problem in clear water like Hawaii. p. 29 Since watching and research trips often occur where hw "aggregate for feeding and reproduction, it could be feared that such activities might displace whales from important habitat. This does not appear to have happened during more than a decade of intensive commercial whale watching near Cape Cod Bay, Mass." p. 29 In general, "the harm of possible disturbance or behavioral habitutation" due to watching and research "should be weighed against the potential benefits" from scientific gains, public education and conservation awareness. 3. Acoustic: industry - Malme, Miles, Tyack et al (1985) exposed feeding hw to noises such as air gun, drilling, production platform and aircraft. "Whales showed no overall pattern of avoidance during 13 experiments" (each w/ 10-40 indivs). Whales dived in response to the airgun, but this "startle response" was thought to be more due to the novelty rather than the gun's intensity. 4. General history of HW hunting and decline - "occurs in all oceans of the world, although less commonly in Arctic regions. Throughout its range, it was heavily exploited by commercial whalers until the middle of this century. The species first received protection in the North Atlantic in 1955 when the International Whaling Commission (IWC) placed a prohibition on non-subsistence hunting by member nations. Proection was extended to the North Pacific and Southern Hemisphere populations after the 1965 hunting season. The humpback was classified as an endangered species whe the U. S. Endangered Species Act was passed in 1973, and it remains so today." p. 1 5. Population estimates - "estimates of present and past abundances and historical carrying capacity are uncertain, and in some instances unknown" p. 2 6. Distribution -

Recovery plan for the humpback whale (Megaptera novaeangliae)

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