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FINAL PROGRAMMATIC BIOLOGICAL OPINION ON U.S. NAVY ACTIVITIES IN THE HAWAII RANGE COMPLEX 2008-2013 of essential behavioral or physiological events, alteration of an animal’s time budget, or some combinations of these responses (Frid and Dill 2002, Romero 2004, Sapolsky et al. 2000, Walker et al. 2005). The behavioral response of animals to human disturbance have been documented to cause animals to abandon nesting and foraging sites (Sutherland and Crockford 1993), cause animals to increase their activity levels and suffer premature deaths or reduced reproductive success when their energy expenditures exceed their energy budgets (Daan et al. 1996, Feare 1976, Giese 1996, Mullner et al. 2004, Waunters et al. 1997), or cause animals to experience higher predation rates when they adopt risk-prone foraging or migratory strategies (Frid and Dill 2002). Based on the evidence available from empirical studies of animal responses to human disturbance, marine animals are likely to exhibit one of several behavioral responses upon being exposed to sonar transmissions: 1. they may exhibit behaviors associated with “allostasis” or physiological stress responses (see the preceding discussion under Allostasis and Boxes B1 or B2 and S of Figure 3, which illustrates the potential consequences of behavioral responses to stress); 2 they may engage in horizontal or vertical avoidance behavior to avoid exposure or continued exposure to a sound that is painful, noxious, or that they perceive as threatening (Box B1 of Figure 3) or may abandon an area; 3 they may respond to an acoustic exposure using evasive or escape behaviors, which a more extreme form of avoidance that is probably accompanied by physiological stress responses (see Box B2 of Figure 3); 4 they may continue their pre-exposure behavior and cope with the behavioral consequences of continued exposure (Box B2 of Figure 3), and 5 they may habituate to a sound or series of sounds or they might not perceive a potential sound as threatening (Box N of Figure 3). In every instance, we are generally concerned about changes in an animals’ pre-disturbance behavior ― for example, a change from resting or foraging to horizontal or vertical avoidance ― because we would generally conclude that animals that do not change their behavioral state or change the rate of particular behavioral acts are either not responding to a stimulus or any responses are physiological (for example, allostasis) rather than behavioral. After being exposed to Navy vessels, sound field associated with active sonar, or both, marine animals might experience one or more of these behavioral responses or they might exhibit a sequence of several of the behaviors presented in the preceding list (for example, an animal might continue its pre-disturbance behavior for a period of time, then abandon an area after it experiences the consequences of physiological stress) or one of these behaviors might accompany responses such as permanent or temporary loss in hearing sensitivity. The narratives that follow summarize the information available on these behavioral responses. BEHAVIORAL AVOIDANCE OF INITIAL OR CONTINUED EXPOSURE. As used in this <strong>Opinion</strong>, behavioral avoidance refers to animals that abandon an area in which active sonar is being used to avoid being exposed to the sonar (regardless of how long it takes them to return), animals that avoid being exposed to the entire sound field produced by active 208
FINAL PROGRAMMATIC BIOLOGICAL OPINION ON U.S. NAVY ACTIVITIES IN THE HAWAII RANGE COMPLEX 2008-2013 sonar; and animals that avoid being exposed to particular received levels within a sound field produced by active sonar. Richardson et al. (1995) noted that avoidance reactions are the most obvious manifestations of disturbance in marine mammals. There are few empirical studies of avoidance responses of free-living cetaceans to mid-frequency sonar. However, Maybaum (1993) conducted sound playback experiments to assess the effects of mid-frequency active sonar on humpback whales in Hawai’ian waters. Specifically, he exposed focal pods to sounds of a 3.3-kHz sonar pulse, a sonar frequency sweep from 3.1 to 3.6 kHz, and a control (blank) tape while monitoring the behavior, movement, and underwater vocalizations. The two types of sonar signals differed in their effects on the humpback whales, the whales exhibited avoidance behavior when exposed to both sounds. The whales responded to the pulse by increasing their distance from the sound source and responded to the frequency sweep by increasing their swimming speeds and track linearity. Bowles et al. (1994) reported that sperm whales appeared to have altered their distribution to avoid being exposed to the low-frequency transmissions associated with the Heard Island Feasibility Test and the whales returned when the transmissions stopped. More recently, Kvadsheim et al. (2007) conducted a controlled exposure experiment in which killer whales (Orcinus orca) that had been fitted with D-tags were exposed to mid-frequency active sonar (Source A: a 1.0 s upsweep 209 dB @ 1 - 2 kHz every 10 seconds for 10 minutes; Source B: with a 1.0 s upsweep 197 dB @ 6 - 7 kHz every 10 s for 10 min). When exposed to Source A, a tagged whale and the group it was traveling with did not appear to avoid the source. When exposed to Source B, the tagged whales along with other whales that had been carousel feeding, ceased feeding during the approach of the sonar and moved rapidly away from the source. When exposed to Source B, Kvadsheim and his co-workers reported that a tagged killer whale seemed to try to avoid further exposure to the sound field by immediately swimming away (horizontally) from the source of the sound; by engaging in a series of erratic and frequently deep dives that seem to take it below the sound field; or by swimming away while engaged in a series of erratic and frequently deep dives. Although the sample sizes in this study are too small to support statistical analysis, the behavioral responses of the orcas were consistent with the results of other studies. In the Caribbean, sperm whales avoided exposure to mid-frequency submarine sonar pulses, in the range 1000 Hz to 10,000 Hz (IWC 2005). Blue and fin whales have occasionally been reported in areas ensonified by airgun pulses; however, there have been no systematic analyses of their behavioral reactions to airguns. Sightings by observers on seismic vessels off the United Kingdom suggest that, at times of good sightability, the number of blue, fin, sei, and humpback whales seen when airguns are shooting are similar to the numbers seen when the airguns are not shooting (Stone 1997, 1998, 2000, 2001). However, fin and sei whale sighting rates were higher when airguns were shooting, which may result from their tendency to remain at or near the surface at times of airgun operation (Stone 2003). The analysis of the combined data from all years indicated that baleen whales stayed farther from airguns during periods of shooting (Stone 2003). Baleen whales also altered course more often during periods of shooting and more were headed away from the vessel at these times, indicating some level of localized avoidance of seismic activity (Stone 2003). Sperm whales responded to military sonar, apparently from a submarine, by dispersing from social aggregations, moving away from the sound source, remaining relatively silent and becoming difficult to approach (Watkins et al. 1985). Brownell (2004) reported the behavioral responses of western gray whales off the northeast coast of Sakhalin 209
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