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
3. underwater detonations associated with an exercise;
4. aircraft operations that occur during an exercise,
5. amphibious landings, and
6. gunfire and missile exercises.
Our section 7 consultation considered the number of endangered or threatened marine animals (that is, those marine
animals that are under the jurisdiction of the National Marine Fisheries Service) that might be exposed to these
different stressors, the nature of those exposures, the animal’s probable responses upon being exposed, and the risks
those responses might pose to individual animals, the populations those individuals represent, and the species those
populations comprise.
2.2.1 Exposure Analyses
As discussed in the introduction to this section of this <strong>Opinion</strong>, exposure analyses are designed to identify the listed
resources that are likely to co-occur with these effects in space and time and the nature of that co-occurrence. Our
exposure analyses are designed to identify the number, age (or life stage), and gender of the individuals that are
likely to be exposed to an Action’s effects and the populations or subpopulations those individuals represent.
Exposure to Navy Vessel Traffic
To estimate the number of endangered or threatened species that are likely to be exposed to vessel traffic associated
with those U.S. Navy training and other activities in the Hawai'i Range Complex, we began with encounter rates
(that is, n/L, or the number of marine mammal groups per unit distance or, in our case, groups per nautical mile)
reported by various investigators in the Hawai'ian Islands (for example, Baird et al. 2003, Baird 2005, Mobley 2001,
2004, 2006, 2008; Norris et al. 2005, Smultea et al. 2008). When data were available, we used encounter rates that
reflected seasonal and geographic differences, then multiplied encounter rates by the number of hours vessels
participating in a training activity might travel multiplied by nominal travel speeds of 10 knots ( = nominal number
of vessels • vessel speed • hours of travel). Finally, we multiplied the resulting number of encounters by the mean
group size for the different species to estimate the number of individuals that might be exposed to vessel traffic. That
is
No. individuals exposed to vessel traffic = (Encounter rate • Hours of transit) • mean group size
where encounter rate might represent the number of groups encountered per unit distance (using nautical miles as the
reference point) or unit time (hours).
Exposure to Active Sonar
Despite the numerous surveys that have been conducted in the Hawai'ian Islands and reports from whale-watch
vessels in the Hawai'ian Islands, there is almost no empirical information on the distribution and abundance of
marine mammals relative to active sonar associated with Navy training exercises. We do not know whether or to
what degree the distribution or abundance of marine animals changes before, during, or after an exercise or whether
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