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
For several years, <strong>NMFS</strong>’ biological opinions have established that most loggerhead sea turtles populations face high
probabilities of extinction as a result of both environmental and demographic stochasticity. Demographic
stochasticity, which is chance variation in the birth or death of an individual of the population, is facilitated by the
increases in mortality rates of loggerhead populations resulting from the premature deaths of individual sea turtles
associated with human activities (either removal of eggs or adult females that are killed on nesting beaches or that
die as a result of being captured in fisheries) or incidental capture and mortality of individuals in various fisheries.
The information available suggests that loggerhead sea turtles have high probabilities of becoming extinct in the
Pacific Ocean unless they are protected from the combined threats of entanglements in fishing gear, overharvests,
and loss of their nesting habitat. The limited data available suggests that nesting aggregations of loggerhead sea
turtles in the Pacific Ocean exist at sizes small enough to be classified as “small” populations (that is, populations
that exhibit population dynamics that increase the extinction probabilities of the species or several of its populations)
as evidenced by biases in the male to female ratios in the Pacific. These small sizes would increase the extinction
probability of these nesting aggregations.
The status of loggerhead sea turtles in the Atlantic Ocean remains uncertain and controversial. For years, the south
Florida nesting aggregation, which is the only major nesting aggregation in the western Atlantic Ocean, had been
assumed to be stable or increasing. However, more recent data demonstrate that this nesting population is currently
declining and probably has been declining for several years. Between 1998 and 2007, nest counts of loggerhead sea
turtles in the State of Florida have declined by almost 50 percent to the lowest levels in the 19 years of Florida’s
monitoring program (Fish and Wildlife Research Institute 2007). Given that (1) the nesting aggregations that account
for almost 90 percent of loggerhead nesting in the western Atlantic Ocean are declining, (2) the other nesting
aggregations in the western Atlantic Ocean are substantially much smaller, and (3) large numbers of sea turtles from
these smaller populations are captured or killed in commercial and other fisheries in the United States each year, we
suspect that the extinction probabilities of loggerhead sea turtle populations in the Atlantic Ocean are only slightly
lower than those of populations in the Pacific Ocean. The principle difference between the Atlantic and the Pacific
may be this: loggerhead sea turtle populations in the Atlantic Ocean may currently be large enough to avoid the
small population dynamics we have discussed previously, but the intensity of the anthropogenic pressure on their
populations (in the form of numbers captured and killed in fisheries alone) appear to be large enough to accelerate
the extinction probabilities of these populations.
Diving and Social Behavior
Studies of loggerhead diving behavior indicate varying mean depths and surface intervals, depending on whether
they were located in shallow coastal areas (short surface intervals) or in deeper, offshore areas (longer surface
intervals). The maximum recorded dive depth for a post-nesting female was 211-233 meters, while mean dive depths
for both a post-nesting female and a subadult were 9-22 meters. Routine dive times for a post-nesting female were
between 15 and 30 minutes, and for a subadult, between 19 and 30 minutes (Sakamoto et al. 1990 cited in Lutcavage
and Lutz 1997). Two loggerheads tagged by Hawai’i-based longline observers in the North Pacific and attached with
satellite-linked dive recorders were tracked for about 5 months. Analysis of the dive data indicate that most of the
dives were very shallow - 70% of the dives were no deeper than 5 meters. In addition, the loggerheads spent
approximately 40% of their time in the top meter and nearly all of their time at depths shallower than 100 meters. On
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