There aren't any primarily acoustics-focused articles this issue. Articles
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Marine Mammal Science
January 2007
Vol. 23 Issue 1
http://www.blackwell-synergy.com/toc/mms/23/1
ARTICLES:
HABITAT SELECTION BY MANATEES IN SARASOTA BAY, FLORIDA
Janet G. Gannon, Kerri M. Scolardi, John E. Reynolds III, Jessica
K. Koelsch, Teresa J. Kessenich
Habitat selection by Florida manatees (Trichechus manatus latirostris)
is influenced by, among other things, availability of food, thermal,
and freshwater resources. However, habitat selection by females with
dependent calves may differ from that of other demographic groups with
regard to the relative importance of these factors. Additional factors
that may influence habitat selection for females with dependent calves
include ambient noise, strong currents, or increased foraging
requirements. We examined distributional data for manatees from aerial
surveys of the coastal waters near Sarasota, Florida, between 1994 and
2004 to determine whether habitat selection by groups of manatees that
included calves differed from that of other groups. We characterized
groups according to their location within seven habitat
types. Enclosed bays not traversed by the Intracoastal Waterway had
the highest proportions of groups with calves. Groups with calves used
a No Entry refuge (from which almost all human use is barred) to a
greater extent than did other groups. Overall, groups with calves
exhibited significantly different habitat selection from groups
without calves (P < 0.001, chi2 = 43.0, df = 6), but this was not
consistent across seasons. During the winter and spring, thermal
requirements influenced manatees to such an extent that all
demographic groups selected habitat similarly.
LESSONS FROM MONITORING TRENDS IN ABUNDANCE OF MARINE MAMMALS
Barbara L. Taylor, Melissa Martinez, Tim Gerrodette, Jay Barlow, Yvana
N. Hrovat
We assessed scientists' ability to detect declines of marine mammal
stocks based on recent levels of survey effort, when the actual
decline is precipitous. We defined a precipitous decline as a 50%
decrease in abundance in 15 yr, at which point a stock could be
legally classified as "depleted" under the U.S. Marine Mammal
Protection Act. We assessed stocks for three categories of cetaceans:
large whales (n = 23, most of which are listed as endangered),
beaked whales (n = 11, potentially vulnerable to anthropogenic
noise), and small whales/dolphins/porpoises (n = 69, bycatch in
fisheries and important abundant predators), for two categories of
pinnipeds with substantially different survey precision: counted on
land (n = 13) and surveyed on ice (n = 5), and for a category
containing polar bear and sea otter stocks (n = 6). The percentage
of precipitous declines that would not be detected as declines was 72%
for large whales, 90% for beaked whales, and 78% for
dolphins/porpoises, 5% for pinnipeds on land, 100% for pinnipeds on
ice, and 55% for polar bears/sea otters (based on a one-tailed t-test,
P = 0.05), given the frequency and precision of recent monitoring
effort. We recommend alternatives to improve performance.
NOTES:
CALF INSPECTIONS OF FISH CATCHES IN BOTTLENOSE DOLPHINS (TURSIOPS
SP.): OPPORTUNITIES FOR OBLIQUE SOCIAL LEARNING?
Janet Mann, Brooke L. Sargeant, Matthew Minor
(Notes do not have an abstract.)
_______________________________________
Jason Gedamke, PhD
Australian Centre for Applied Marine Mammal Science
Australian Government Antarctic Division
Channel Highway, Kingston
Tasmania 7050
Australia
ph: 61-3-6232-3153
FAX: 61-3-6232-3449
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