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 The Navy has conducted Rim of the Pacific exercises every second year since 1968 and anti-submarine warfare activities have occurred in each of the 19 exercises that have occurred thus far. This observation supports several different inferences. One line of reasoning is: if the mid-frequency sonar employed during those exercises killed or injured whales whenever the whales encountered the sonar, mass stranding events are likely to have occurred at least once or twice over the 38-year period since 1968. With one exception, there is little evidence of a pattern in the record of stranding events reported for the main Hawai’ian Islands. A second line of reasoning leads to a very different conclusion: the absence of reports of stranding events may result from the small number of people searching for stranded animals relative to the coastline of Hawai’i —although stranding events have been reported in the Hawai’ian Islands since 1937, no toothed whales were reported until 1950 — or it may be because only a fraction of the whales that are killed or injured in Hawai’ian waters strand (as opposed to sinking, being transported to the open ocean by the strong currents that flow across the northern shore of the islands, or being eaten by predators like sharks). Faerber and Baird (2007) presented evidence that supports this inference. They compared patterns of beaked whale stranding events in the Canary Islands and the main Hawai’ian Islands (they compared water depths immediately adjacent to shore, accessibility of shorelines, and population densities relative to land area and amount of shoreline) and concluded that beaked whales were less likely to strand in the main Hawai’ian Islands and were not likely to be detected if they did strand. Finally, the apparent absence of stranding events coincident with the 38 years of antisubmarine warfare training exercises in waters off the main Hawai’ian islands could also suggest that mid-frequency sonar transmissions pose a hazard to cetaceans in some circumstances, but not others (for example, see the discussion under Behavioral Avoidance). 5.3.4 The Probable Responses of Listed Species to Mid-Frequency Active Sonar Based on the evidence available, the mid-frequency active sonars associated with the training exercises and other activities the U.S. Navy plans to conduct in the Hawai'i Range Complex each year from December 2008 through December 2013 are not likely to kill or injure threatened or endangered marine mammals. However, little is known about the effect of short-term disruptions of a marine mammal’s normal behavior (Richardson et al. 1995). Most of the evidence available suggests that active sonar associated with the Navy’s activites are not likely to kill or fatally injure endangered or threatened marine animals in the Hawai’ian Islands as a result of direct exposure or as an indirect result of an exposure event: if marine animals were likely to be killed as a direct or indirect result of being exposed to this sonar, we would have received more reports of such deaths or fatal injuries at some point in the relatively long history of Navy training in the Hawai’ian Islands. Similarly, the evidence available also does not lead us to expect threatened or endangered cetaceans to strand or suffer resonance effects from the mid-frequency sonars associated with the training exercises and other activities the U.S. Navy plans to conduct in the Hawai'i Range Complex over the next five years. In this case, the absence of such reports given the number of exercises the Navy has conducted in the Hawai’i Range Complex suggests that exposing endangered or threatened marine animals to active sonar associated with Navy activities in the action area are not likely to kill or fatally injure those animals. Any direct or indirect effects of the Navy’s training and other activities in the Hawai'i Range Complex are more likely to affect the communication, 224
FINAL PROGRAMMATIC BIOLOGICAL OPINION ON U.S. NAVY ACTIVITIES IN THE HAWAII RANGE COMPLEX 2008-2013 behavior, and stress loading of endangered and threatened marine animals in the range complex. The effects of those responses are much more difficult to detect, although those responses all are known to reduce the fitness of individual animals and, as a result, their consequences are not trivial. BLUE WHALES. During future Rim of the Pacific Exercises, the first scenario (which assumed that animals would not move) identified 140 instances in which blue whales might be exposed to mid-frequency active sonar at received levels between 140 and 195 dB and no instances in which blue whales might be exposed at received levels between 195 and 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 351 instances in which blue whales might be exposed to mid-frequency active sonar transmissions at received levels between 140 and 195 dB. No blue whales would be exposed to received levels greater than 195 dB associated with these other training activities. Of the 489 instances in which <strong>NMFS</strong>’ exposure models identified blue whales that might be exposed to midfrequency active sonar at received levels between 140 and 195 dB, about 286 of those instances would involve exposures at received levels between 140 and 150 dB. Another 136 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. In the event blue whales are exposed to mid-frequency sonar, the information available on blue whales exposed to received levels of active mid-frequency sonar suggests that they are not likely to hear mid-frequency (1 kHz–10 kHz) sounds. Blue whales vocalizations include a variety of sounds described as low frequency moans or long pulses in the 10-100 Hz band (Cummings and Thompson 1971; Edds 1982; Thompson and Friedl 1982; McDonald et al. 1995; Clark and Fristrup 1997; Rivers 1997). The most typical signals are very long, patterned sequences of tonal infrasonic sounds in the 15-40 Hz range. Ketten (1997) reports the frequencies of maximum energy between 12 and 18 Hz. Short sequences of rapid calls in the 30-90 Hz band are associated with animals in social groups (Clark personal observation and McDonald personal communication cited in Ketten 1997). The context for the 30-90 Hz calls suggests that they are used to communicate but do not appear to be related to reproduction. Blue whale moans within the frequency range of 12.5-200 Hz, with pulse duration up to 36 seconds, have been recorded off Chile (Cummings and Thompson 1971). The whale produced a short, 390 Hz pulse during the moan. Based on this information blue whales exposed to received levels of active mid-frequency sonar are not likely to hear midfrequency sounds; if they do not hear the sounds, they are not likely to respond physiologically or behaviorally to those received levels. PROBABLE RESPONSE OF FIN WHALES. During future Rim of the Pacific Exercises, the first scenario (which assumed that animals would not move) identified 634 instances in which fin whales might be exposed to mid-frequency active sonar at received levels between 140 and 195 dB and one instance in which fin whales might be exposed at received levels between 195 and 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 146 instances in which fin whales might be exposed to mid-frequency active sonar transmissions at received levels between 140 and 225
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