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
Vocalizations and Hearing
The information on green turtle hearing is very limited. Ridgway et al. (1969) studied the auditory evoked potentials
of three green sea turtles (in air and through mechanical stimulation of the ear) and concluded that their maximum
sensitivity occurred from 300 to 400 Hz with rapid declines for tones at lower and higher frequencies. They reported
an upper limit for cochlear potentials without injury of 2000 Hz and a practical limit of about 1000 Hz. This is
similar to estimates for loggerhead sea turtles, which had most sensitive hearing between 250 and 1000 Hz, with
rapid decline above 1000 Hz (Bartol et al. 1999).
In a study of the auditory brainstem responses of subadult green sea turtles, Bartol and Ketten (2006) reported
responses to frequencies between 100 and 500 Hz; with highest sensitivity between 200 and 400 Hz. They reported
that two juvenile green turtles had hearing sensitivities that were slightly broader in range: they responded to sounds
at freqnencies from 100 to 800 Hz, with highest hearing sensitivities from 600 to 700 Hz.
These hearing sensitivities are similar to the hearing sensitivities reported for two terrestrial species: pond turtles
(Pseudemys scripta) and wood turtles (Chrysemys inscuplta). Pond turtles are reported to have best hearing
responsiveness between 200 and 700 Hz, with slow declines below 100 Hz and rapid declines above 700 Hz and
almost no sensitivity above 3000 Hz (Wever and Vernon 1956) the latter has sensitivities up to about 500 Hz,
followed by a rapid decline above 1000 Hz and almost no responses beyond 3000 or 4000 Hz (Peterson 1966).
3.3.7 Leatherback Sea Turtle
Distribution
Leatherback turtles are widely distributed throughout the oceans of the world. The species is found in four main
regions of the world: the Pacific, Atlantic, and Indian Oceans, and the Caribbean Sea. Leatherbacks also occur in the
Mediterranean Sea, although they are not known to nest there. The four main regional areas may further be divided
into nesting aggregations. Leatherback turtles are found on the western and eastern coasts of the Pacific Ocean, with
nesting aggregations in Mexico and Costa Rica (eastern Pacific) and Malaysia, Indonesia, Australia, the Solomon
Islands, Papua New Guinea, Thailand, and Fiji (western Pacific). In the Atlantic Ocean, leatherback nesting
aggregations have been documented in Gabon, Sao Tome and Principe, French Guiana, Suriname, and Florida. In
the Caribbean, leatherbacks nest in the U.S. Virgin Islands and Puerto Rico. In the Indian Ocean, leatherback nesting
aggregations are reported in India and Sri Lanka.
Leatherback sea turtles are highly migratory, exploiting convergence zones and upwelling areas in the open ocean,
along continental margins, and in archipelagic waters (Morreale et al. 1994, Eckert 1998, Eckert 1999a). In a single
year, a leatherback may swim more than 10,000 kilometers (Eckert 1998). In the North Atlantic Ocean, leatherback
turtles regularly occur in deep waters (>328 ft), and an aerial survey study in the north Atlantic sighted leatherback
turtles in water depths ranging from 3 to 13,618 ft, with a median sighting depth of 131.6 ft (CeTAP 1982). This
same study found leatherbacks in waters ranging from 7 to 27.2°C. In the Pacific Ocean, leatherback turtles have the
most extensive range of any living reptile and have been reported in all pelagic waters of the Pacific between 71°N
and 47°S latitude and in all other major pelagic ocean habitats (<strong>NMFS</strong> and USFWS 1998). Leatherback turtles lead a
completely pelagic existence, foraging widely in temperate waters except during the nesting season, when gravid
females return to tropical beaches to lay eggs. Males are rarely observed near nesting areas, and it has been
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