[MARMAM] The use of sonar to detect manatees
gonzalez.socoloske at duke.edu
Tue Oct 27 13:24:06 PDT 2009
It is my distinct pleasure to announce the publication of the following
the open access journal Endangered Species Research. Full text pdf can be
downloaded at http://www.intres.com/abstracts/esr/v8/n3/p249-257/
Gonzalez-Socoloske D, Olivera-Gomez LD, Ford RE (2009) Detection of
West Indian manatees Trichechus manatus using side-scan sonar. Endang Species
ABSTRACT: Turbid and tannin-stained waterways are difficult habitats to study
and present problems with respect to the management of aquatic fauna, and
especially of endangered and cryptic animals such as manatees Trichechus spp.
Linnaeus. Throughout much of the range of the extant trichechid species (T.
inunguis, T. manatus, and T. senegalensis), the scientific approaches that are
used successfully to document the status of the Florida subspecies (T. m.
latirostris) are not feasible, due either to constraints associated with
habitat or to the high costs involved. We examined the use of side-scan sonar
as a novel way to acoustically detect free-ranging West Indian manatees (T. m.
latirostris and T. m. manatus), and evaluated the effectiveness of the
technology under various environmental conditions. Blind transects, where one
observer only looked at the sonar, were conducted in Mexico and Florida to
confirm that manatees could be detected and to determine a preliminary manatee
detection rate for the sonar unit. Quality sonar images were produced under
most environmental conditions examined, provided that ambient water movement
was low. Manatees were successfully detected laterally up to 18 m, and
acoustic images were produced when the animals were stationary and oriented
parallel to the boat. Preliminary detection was 81 and 93% in Florida and
Mexico, respectively. We conclude that over limited areas, and under certain
environmental conditions, side-scan sonar is a cost-effective option to
accurately detect manatees and provide important information for conservation
decisions. Like all survey techniques, it has limitations, but its unique
advantages will be a welcomed alternative to aerial surveys and visual boat
surveys of opaque waterways.
University Program in Ecology
Nicholas School of Environment
dg52 at duke.edu
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