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

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FINAL PROGRAMMATIC BIOLOGICAL OPINION ON U.S. NAVY ACTIVITIES IN THE HAWAII RANGE COMPLEX 2008-2013 3 Feeding area vocalizations that are less frequent, but tend to be 20Hz – 2 kHz with estimated sources levels in excess of 175 dB re 1 uPa-m (Thompson et al. 1986, Richardson et al. 1995). Sounds often associated with possible aggressive behavior by males (Silber 1986,Tyack 1983) are quite different from songs, extending from 50 Hz to 10 kHz (or higher), with most energy in components below 3 kHz. These sounds appear to have an effective range of up to 9 km (Tyack and Whitehead 1983). More recently, Au et al. (2006) conducted field investigations of humpback whale songs. They concluded that humpback whales have an upper frequency limit reaching as high as 24 kHz. Based on this information, it is reasonable to assume that the active mid-frequency sonar the U.S. Navy would employ during the proposed Rim of the Pacific Exercises and RDT&E activities are within the hearing and vocalization ranges of humpback whales. There is limited information on how humpback whales are likely to respond upon being exposed to mid-frequency active sonar (most of the information available addresses their probable responses to low-frequency active sonar or impulsive sound sources). Humpback whales responded to sonar in the 3.1–3.6 kHz by swimming away from the sound source or by increasing their velocity (Maybaum 1990, 1993). The frequency or duration of their dives or the rate of underwater vocalizations, however, did not change. Humpback whales have been known to react to low frequency industrial noises at estimated received levels of 115- 124 dB (Malme et al. 1985), and to calls of other humpback whales at received levels as low as 102 dB (Frankel et al. 1995). Malme et al. (1985) found no clear response to playbacks of drill ship and oil production platform noises at received levels up to 116 dB re 1 μPa. Studies of reactions to airgun noises were inconclusive (Malme et al. 1985). Humpback whales on the breeding grounds did not stop singing in response to underwater explosions (Payne and McVay 1971). Humpback whales on feeding grounds did not alter short-term behavior or distribution in response to explosions with received levels of about 150dB re 1 μPa/Hz at 350Hz (Lien et al. 1993, Todd et al. 1996). However, at least two individuals were probably killed by the high-intensity, impulsed blasts and had extensive mechanical injuries in their ears (Ketten et al. 1993, Todd et al. 1996). The explosions may also have increased the number of humpback whales entangled in fishing nets as they avoided the blasts (Todd et al. 1996). Frankel and Clark (1998) showed that breeding humpbacks showed only a slight statistical reaction to playbacks of 60 - 90 Hz sounds with a received level of up to 190 dB. Although these studies have demonstrated that humpback whales will exhibit short-term behavioral reactions to boat traffic and playbacks of industrial noise, the long-term effects of these disturbances on the individuals exposed to them are not known. Because their hearing range appears to overlap with the frequency range of mid-frequency active, we assume that some of the humpback whales that are exposed to mid-frequency active sonar during one or more of the proposed exercises might experience acoustic masking, impairment of acoustic communication, behavioral disturbance, and physiological stress responses as a result of their exposure. PROBABLE RESPONSES OF SEI WHALES. During future Rim of the Pacific Exercises, the first scenario (which assumed that animals would not move) identified 70 instances in which sei whales might be exposed to mid-frequency active sonar at received levels between 140 and 195 dB. During the other anti-submarine exercises (USWEX, TRACKEX, and TORPEX) the U.S. Navy plans to conduct in the Hawai’i Range Complex each year, the first scenario identified another 105 instances in which sei whales might be exposed to mid-frequency active sonar transmissions at received 228
FINAL PROGRAMMATIC BIOLOGICAL OPINION ON U.S. NAVY ACTIVITIES IN THE HAWAII RANGE COMPLEX 2008-2013 levels between 140 and 195 dB. No sei whales would be exposed to received levels greater than 195 dB associated with these other training activities. Of the 165 instances in which <strong>NMFS</strong>’ exposure models identified sei whales that might be exposed to mid-frequency active sonar at received levels between 140 and 195 dB, about 196 of those instances would involve exposures at received levels between 140 and 150 dB. Another 49 of those instances would involve exposures at received levels between 150 and 160 dB. The balance of the exposures would occur at received levels greater than 160 dB. As discussed in the Status of the Species section of this opinion, we have no specific information on the sounds produced by sei whales or their sensitivity to sounds in their environment. Based on their anatomical and physiological similarities to both blue and fin whales, we assume that the hearing thresholds of sei whales will be similar as well and will be centered on low-frequencies in the 10-200 Hz. This information would lead us to conclude that, like blue and fin whales, sei whales exposed to these received levels of active mid-frequency sonar are not likely to respond if they are exposed to mid-frequency (1 kHz–10 kHz) sounds. PROBABLE RESPONSES OF SPERM WHALES. During future Rim of the Pacific Exercises, the first scenario (which assumed that animals would not move) identified 1,952 instances in which sperm whales might be exposed to midfrequency active sonar at received levels between 140 and 195 dB, five instances in which sperm whales might be exposed at received levels between 195 and 215 dB, and one instance in which sperm whales might be exposed at received levels greater than 215 dB. During the other anti-submarine exercises (USWEX, TRACKEX, and TORPEX) the U.S. Navy plans to conduct in the Hawai’i Range Complex each year, the first scenario identified another 587 instances in which sperm whales might be exposed to mid-frequency active sonar transmissions at received levels between 140 and 195 dB, 1 instance in which sperm whales might be exposed at received levels between 195 and 215 dB, and one instance in which sperm whales might be exposed at received levels greater than 215 dB over the five-year period of the proposed regulations. Based on their hearing sensitivities, which overlap the frequency range of mid-frequency active sonar, sonar transmissions might mask environmental cues at the lower range of sperm whale hearing. Although there is no published audiogram for sperm whales, sperm whales would be expected to have good, high frequency hearing because their inner ear resembles that of most dolphins, and appears tailored for ultrasonic (>20 kHz) reception (Ketten 1994). The only data on the hearing range of sperm whales are evoked potentials from a stranded neonate, which suggest that neonatal sperm whales respond to sounds from 2.5 to 60 kHz. Based on the frequencies of their vocalizations, which overlap the frequency range of mid-frequency active sonar, sonar transmissions might temporarily reduce the active space of sperm whale vocalizations. Most of the energy of sperm whales clicks is concentrated at 2 to 4 kHz and 10 to 16 kHz, which overlaps with the mid-frequency sonar. Other studies indicate sperm whales’ wide-band clicks contain energy between 0.1 and 20 kHz (Weilgart and Whitehead 1993, Goold and Jones 1995). Ridgway and Carder (2001) measured low-frequency, high amplitude clicks with peak frequencies at 500 Hz to 3 kHz from a neonate sperm whale. There is some evidence of disruptions of clicking and behavior from sonars (Goold 1999, Watkins and Scheville1975, Watkins et al. 1985), pingers (Watkins and Scheville 1975), the Heard Island Feasability Test 229
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