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
exposed to higher received levels of active sonar (received levels greater than 195 dB) at a faster rate than
they would avoid lower received levels; we simulated avoidance by reducing marine mammal densities
exponentially over time;
3. a scenario focused on humpback whales and assumed that humpback whale densities varied over the winter
season in Hawai'i. Specifically, this scenario assumed that humpback whale densities during the winter
months would be described by a standard normal distribution with densities increasing from zero starting in
October, reaching a maximum between late-February through March, then declining to zero again through
the spring.
Every scenario assumed ship speeds of 10 knots (or 18.25 kilometers per hour), which is the same assumption
contained in the Navy’s models. The “sensory field” (2r) for every scenario represented the U.S. Navy’s estimates of
the area that would be ensonified at different received levels presented in the U.S. Navy’s Environmental Impact
Statements for the Hawai’i Range Complex, adjusted to eliminate overlap (U.S. Navy 2007, 2008). Finally, every
scenario was based on the Navy’s estimates of the number of hours of the different kinds of active sonar that would
be employed in the different exercises (future Rim of the Pacific Exercises and other anti-submarine warfare exercises).
2.2.2 Response Analyses
As discussed in the introduction to this section of this <strong>Opinion</strong>, our response analyses are designed to identify the
physical, physiological, and behavioral responses of endangered or threatened species that are likely to be exposed to
stressors produced by an action. Because the responses of animals to a potential stressor are influenced by the
animal’s pre-existing physical, physiological, or behavioral state, our response analyses consider the Status of the
Species and the impacts of the Environmental Baseline.
The potential stressors associated with the training exercises the U.S. Navy proposes to conduct in the Hawai'i
Range Complex are likely to produce two general classes of responses:
1. responses that are influenced by an animal’s assessment of whether a potential stressor poses a threat or risk
(see Figure 3: Animal Does Not Respond, Stress Response, and Behavioral Response). For example, an
animal’s behavioral response to active sonar or an approaching vessel will depend on whether (a) an animal
detects the some physical, visual, or acoustic cue from the sonar or vessel and (b) the animal classifies those
cues as a potential threat (Blumstein and Bouskila 1996). The results of that assessment, which is
influenced by the animal’s physical and physiological state, can trigger physiological stress responses or
lead to the animal to execute a behavioral response from its behavioral repertoire using a decision-making
process that weighs the costs and benefits of alternative behaviors and recognizes the existing of trade-offs
(Beale 2007, Blumstein and Bouskila 1996).
2. responses that are not influenced by the animal’s assessment of whether a potential stressor poses a threat or
risk (see Figure 3: Physical Damage, Mask Signal Reception, and Impair Call/Song Transmission).
Figure 3 illustrates the structure of our response analyses and shows the relationships between exposures, responses,
and potential fitness consequences to individual animals that experience or exhibit particular responses or sets of
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