Gulf of Mexico Cetacean Project II

Project Description
While GulfCet I provided important information, it was not designed to
address fully the question: "What habitats do these animals prefer?"
GulfCet II (1996-1997) - the extension study - was sponsored and
administered by the Biological Resources Division of the
U.S. Geological Survey to meet information needs of the MMS. One need
was to determine the distribution and abundance of whales and dolphins
in the eastern Gulf, an area of potential future oil and gas
exploration and production. GulfCet II also continued surveys in the
western and central Gulf to monitor the abundance and distribution of
cetaceans. Another component of GulfCet II was to conduct focal
studies specifically designed to address whale and dolphin
associations with habitats (physical environment and available prey).
These studies used satellite altimeter data to plan transect lines to
survey through cyclonic and anticyclonic gyres and determine cetacean
and seabird abundance within various hydrographic features. GulfCet
II was the only marine mammal study that used an ecosystem approach,
integrating visual and acoustic surveys with satellite imaging,
hydrographic collections, and trawl samples.

The GulfCet II Study has shown us that sperm whales, and other
cetaceans, are found in conjunction with area of upwelling and
nutrient enrichment that enhance productivity and prey abundance.
Cetaceans in the northern Gulf of Mexico concentrate along the
continental slope in or near cyclones (upwelled waters) and the
confluence of cyclone-anticyclone eddy pairs. Cyclones also had the
greatest diversity of seabird species, although habitat use varied
among species. High numbers of zooplankton, lanternfish, and squid
were found inside cyclone and confluence areas. While whales and
dolphins do not occur randomly in the gulf, it is important to
remember the dynamic nature of the hydrographic features with which
they associate. As the features move and change, prey distribution
changes and moves, and so will the presence and movements of whales
and dolphins.

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