NMFS Biological Opinion on U.S. Navy training ... - Govsupport.us

FINAL PROGRAMMATIC BIOLOGICAL OPINION ON U.S. NAVY ACTIVITIES IN THE HAWAII RANGE COMPLEX 2008-2013
from a paddle raft when their perches were closer to the river or were closer to the ground (Steidl and Anthony
1996).
One consequence of behavioral avoidance results from changing the energetics of marine mammals because of the
energy required to avoid surface vessels or the sound field associated with active sonar (Frid and Dill 2002). Most
animals can avoid that energetic cost by swimming away at slow speeds or those speeds that are at or near the
minimum cost of transport (Miksis-Olds 2006), as has been demonstrated in Florida manatees (Hartman 1979,
Miksis-Olds 2006).
Those costs increase, however, when animals shift from a resting state, which is designed to conserve an animal’s
energy, to an active state that consumes energy the animal would have conserved it they had not been disturbed. In
the case of humpback whales, lactating females with calves should spend more time in a resting state because of
high energetic costs of lactating and their inability to compensate for those costs by feeding (humpback whales
generally do not feed in their calving areas). Marine mammals that have been disturbed by anthropogenic noise and
vessel approaches are commonly reported to shift from restirng behavioral states to active behavioral states, which
would imply that they incur an energy cost. Morete et al. (2007) reported that undisturbed humpback whale cows
that were accompanied by their calves were frequently observed resting while their calves circled them (milling) and
rolling interspersed with dives. When vessels approached, the amount of time cows and calves spent resting and
milling, respectively declined significantly. These results are similar to those reported by Scheidat et al. (2004) for
the humpback whales they observed off the coast of Ecuador.
Constantine and Brunton (2001) reported that bottlenose dolphins in the Bay of Islands, New Zealand only engaged
in resting behavior 5 percent of the time when vessels were within 300 meters compared with 83 percent of the time
when vessels were not present. Miksis-Olds (2006) and Miksis-Olds et al. (2005) reported that Florida manatees in
Sarasota Bay, Florida, reduced the amount of time they spent milling and increased the amount of time they spent
feeding when background noise levels increased. Although the acute costs of these changes in behavior are not likely
to exceed an animals’ ability to compensate, the chronic costs of these behavioral shifts are uncertain.
Based on the evidence available, most of the endangered whales that are being considered in this <strong>Opinion</strong> are likely
to avoid being exposed to the exercises or, if they are exposed, are likely to avoid continued exposure to the
exercises. Blue, fin, humpback, sei, and sperm whales would probably be alerted to the start of an exercise by lowfrequency
sounds produced by Navy surface vessels entering an area to begin an exercise. Because the main
Hawai’ian Islands do not appear to be an important feeding area or calving area for fin, sei, and sperm whales, they
seem likely to try to avoid an area in which surface vessels are moving at tactical speeds accompanied by active
sonar transmissions, low-frequency sounds produced by aircraft and helicopters, sonobuoys, and submarines.
The main Hawai’ian Islands are an important breeding and calving area for humpback whales, however. If breeding,
adult hunpback whales try to avoid being exposed to mid-frequency active sonar and that avoidance behavior
prevented them from breeding, the avoidance behavior would have reduced the fitness of any humpback whales that
made this trade-off (avoiding the sonar rather than breeding). Adult humpback whales with calves do not seem likely
to try to avoid continued exposure if they are accompanied by very young calves because swimming at speeds that
would allow them to avoid exposures would separate them from calves that could not sustain such swimming speeds.
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