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 Navy then calculated an impact volume, which is the volume of water in which an acoustic metric exceeds a specified threshold; in this case, the metric is either energy flux density (in a limited band or across a full band), peak pressure, or positive impulse. By multiplying impact volumes with estimates of animal densities in three dimensions (densities distributed by area and depth), the U.S. Navy estimated the expected number of animals that might be exposed to an acoustic metric (energy flux density, peak pressure, or positive impulse) at levels that exceed specified thresholds. Specifically, the U.S. Navy calculated impact volumes for sonar operations (using energy flux density to estimate the probability of injury), peak pressure, and a Goertner modified positive impulse (for onset of slight lung injury associated with explosions). To calculate impact volumes, the U.S. Navy used a “risk continuum” (a curve that related the probability of a behavioral response given exposure to a received level that is generally represented by sound pressure level, but included sound exposure level to deal with threshold shifts) that the U.S. Navy and ong>NMFSong> developed to the area of the representative provinces then multiplied that area by a vector that represented the densities of the different species of marine animals that are expected to occur in the Hawai'i Range Complex. The risk continuum, which the U.S. Navy adapted from a mathematical model developed by Feller (1968), was estimated using three data sources: data from controlled experiments conducted at the U.S. Navy’s Space and Naval Warfare Systems Center in San Diego, California (Finneran et al. 2001, 2003, 2005; Finneran and Schlundt 2004; Schlundt et al. 2000), data from a reconstruction of an incident in which killer whales were probably exposed to mid-frequency active sonar (Fromm 2004, Department of the Navy 2003), and a suite of studies of the response of baleen whales to low-frequency sound sources (Nowacek et al. 2004). Exposure Estimates Produced by this Approach This approach to estimating the number of endangered and threatened marine mammals that might be “taken” as a result of being exposed to active sonar associated with the activities the U.S. Navy plans to conduct in the Hawai’i Range Complex each over the five-year period beginning in December 2008 produced the following results: BLUE WHALES. The Navy argued that because no density information is available for blue whales in Hawai’ian waters and blue whales have not been seen during surveys that few blue whales occur in the Hawai'i Range Complex. As a result, the Navy did not model the number of blue whales that might be exposed to training events in the Hawai'i Range Complex. FIN WHALES. During future Rim of the Pacific exercises, the Navy’s estimates identified 14 instances in which fin whales might be exposed to received levels that cause them to respond with behaviors that ong>NMFSong> would classify as harassment (as that term is defined for the purposes of the Marine Mammal Protection Act of 1972). During the other anti-submarine exercises the U.S. Navy plans to conduct in the Hawai’i Range Complex each over the fiveyear period beginning in December 2008, the Navy’s estimates identified another 14 instances in which fin whales might exhibit behaviors that ong>NMFSong> would classify as harassment. No fin whales would accumulate energy sufficient to result in temporary or permanent shifts in hearing sensitivity. The 60 instances in which fin whales might be exposed to the mid-frequency active sonar during activities the activities the U.S. Navy plans to conduct in the Hawai’i Range Complex each over the five-year period beginning in 174

FINAL PROGRAMMATIC BIOLOGICAL OPINION ON U.S. NAVY ACTIVITIES IN THE HAWAII RANGE COMPLEX 2008-2013 December 2008 would represent individuals from the Hawai’ian population (or “stock”) of fin whales. We assume that any age or gender might be exposed to those received levels. Table 12. The U.S. Navy’s estimates of the number of individuals of different endangered species that might experience behavioral harassment, temporary threshold shifts (TTS), or permanent threshold shifts (PTS) as a result of being exposed to active sonar associated with future Rim of the Pacific exercises. The column labeled “DEIS/OEIS Dose Function” are comparable estimates based on the model the Navy used in earlier NEPA documents (from U.S. Navy 2008b) Marine Mammals Risk Function DEIS/OEIS Dose Function 195 dB TTS 215 dB PTS Fin whale 1 14 7 0 0 Sei whale 1 14 7 0 0 Humpback whale 1 0 - 0 - Sperm whale 1 245 115 3 0 Monk seal 1 35 49 1 0 Sub-Total 308 178 4 0 Table 13. The U.S. Navy’s estimates of the number of individuals of different endangered species that might experience behavioral harassment, temporary threshold shifts (TTS), or permanent threshold shifts (PTS) as a result of being exposed to active sonar associated with the anti-submarine warfare exercises (other than RIMPAC) the Navy plans to conduct in the Hawai’i Range Complex from December 2008 through December 2013. The column labeled “DEIS/OEIS Dose Function” are comparable estimates based on the model the Navy used in earlier NEPA documents (from U.S. Navy 2008b) Marine Mammals Risk DEIS/OEIS Dose Function Function 195 dB TTS 215 dB PTS Fin whale 1 46 28 0 0 Sei whale 1 46 28 0 0 Humpback whale 9,677 8,938 199 0 Sperm whale 1 758 391 9 0 Monk seal 1 104 177 3 0 Sub-Total 10,631 18,498 211 0 TOTAL (of Tables 13 and 14) 22,591 21174 277 0 Note: 1 These estimates are based on an assumption that densities of fin and sei whales are the same as those of false killer whale (0.0001 animals per square kilometer) because the three species have a similar size population within the Hawai’i Range Complex; Risk Function Curve: 195 dB – TTS 195-215 dB re 1 µPa 2 -s, 215 dB- PTS >215 dB re 1 µPa 2 -s; dB = decibel HUMPBACK WHALES. Because Rim of the Pacific exercises typically occur in the Hawai’i Range Complex in July when humpback whales do not occur in waters off Hawai’i, humpback whales would not be exposed to the potential stressors associated with that exercise. During the other anti-submarine exercises the U.S. Navy plans to conduct in the Hawai’i Range Complex from December 2008 through December 2013, the Navy’s estimates identified another 9,677 instances in which humpback whales might be exposed to received levels that cause them to exhibit behaviors that ong>NMFSong> would classify as harassment (as that term is defined for the purposes of the Marine Mammal Protection Act of 1972). Of that total, the Navy estimated that 199 humpback whales might accumulate energy sufficient to result in temporary shifts in hearing sensitivity, but no humpback whales would accumulate energy sufficient to result in permanent losses in hearing sensitivity. Because of the annual migratory pattern of humpback whales, we would assume that any of these 9,677 instances in which humpback whales would be exposed would occur between October and April or May of the following year. If 175

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