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
have accumulated energy equivalent to between 173 and 195 dB on one occasion; another 4 instances in which
individual sei whales would have accumulated this energy equivalent on two occasions; and one instance in which
an individual sei whale would have accumulated this energy equivalent on three occasions. The Navy’s simulations
also identified 1 instance in which a sei whale might have accumulated energy equivalent to 195 – 215 dB (a total of
28 instances in which sei whales might have accumulated energy equivalent to more than 173 dB).
SPERM WHALES. The simulations the Navy conducted for the 2006 RIMPAC exercise identified 1,417 instances in
which sperm whales might have accumulated energy equivalent to between 173 and 195 dB during the 2006 RIMPAC
exercise. Based on our analyses of those estimates, <strong>NMFS</strong>’ 2006 <strong>Opinion</strong> assumed that 967 of these instances might
have involved individual sperm whales that have accumulated energy equivalent to between 173 and 195 dB on one
occasion; 193 of these instances would have involved individual sperm whales that might have accumulated energy
equivalent to between 173 and 195 dB on two occasions; 20 of these instances would have involved individual
sperm whales that might have accumulated energy equivalent to between 173 and 195 dB on 3 occasions; and 1
instance in which a sperm whale might have accumulated this energy equivalent on one occasion.
The Navy’s simulations also identified 34 instances in which sperm whales might have accumulated energy that is
equivalent to between 195 and 215 dB during the proposed RIMPAC exercise. Based on our analyses of those
estimates, <strong>NMFS</strong>’ 2006 <strong>Opinion</strong> assumed that 23 of these instances might have involved individual sperm whales that
might have accumulated energy equivalent to between 173 and 195 dB on one occasion; 5 of these instances would
have involved individual sperm whales that might have accumulated energy equivalent to between 173 and 195 dB
on two occasions; and 1 instance in which a sperm whale might have accumulated this energy equivalent on one
occasion.
Data on the hearing range of sperm whales were developed using evoked potentials from a stranded neonate (Carder
and Ridgway 1991). These data suggest that neonatal sperm whales respond to sounds with frequencies between 2.5
and 60 kHz. The sperm whales that might be exposed to future RIMPAC exercises, particular mid-frequency sonar
transmissions and ship traffic, would represent individuals from a Hawai’ian population (or “stock”). Sperm whales
are widely distributed throughout the Hawai’ian Islands year-round (Rice 1960, Shallenberger 1981, Lee 1993,
Mobley et al. 2000). Sperm whale clicks recorded from hydrophones off Oahu confirm the presence of sperm whales
near the Hawai’ian Islands throughout the year (Thompson and Friedl 1982). Sperm whales primarily occur seaward
of the shelf break in the Hawai’ian Islands Operating Area and rarely occur from the shore to the shelf break.
5.2.1.2 U.S. Navy Exposure Estimates for Proposed Actions in the Hawai'i Range Complex
Over the past year, the U.S. Navy updated the approach it used to estimate the number of marine mammals that
might be exposed to the activities the U.S. Navy plans to conduct in the Hawai’i Range Complex each year over the
five-year period beginning in December 2008. What follows is a brief summary of the Navy’s current approach, for
more details, refer to Appendix K of the U.S. Navy’s Environmental Impact Statement (draft or final) on the Hawai'i
Range Complex (U.S. Navy 2007 and 2008a).
The U.S. Navy’s updated approach focuses on a suite of representative provinces based on sound velocity profiles,
bathymetries, and bottom types. Within each of these provinces, the U.S. Navy modeled transmission losses in 5
meter increments and used the results to build sound fields (based on maximum sound pressure levels). The U.S.
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