Volume 4, Number 3, Winter 1996

"Thar she blows!"
GulfCet cruise news

Douglas C. Biggs and Randall W. Davis

In October, R/V Gyre was used for a 19-day research cruise as part of a long-term program to study the distribution and abundance of marine mammals in the northern Gulf of Mexico. The program is nicknamed "GulfCet" because it deals with gulf populations of dolphins and whales, which together form a subgroup of marine mammals called cetaceans. The goal of the GulfCet program is to take a visual and acoustic census of marine mammals in the northeastern gulf. Dr. Randall Davis, Head of the Department of Marine Biology at Texas A&M University-Galveston, is the program manager of GulfCet and was chief scientist for the Gyre cruise. Visual observations of mammals were the task of two three-person teams of cetacean spotters who were on watch from the flying bridge every day, from first light through dusk, using "bigeye" binoculars. A group of acoustic spotters, under the direction of Dr. William Evans and Dr. Jeff Norris of the Center for Marine Bioacoustics at Texas A&M-Galveston, made simultaneous acoustic recordings of cetacean vocalizations using a towed array of hydrophones. The acoustic array was towed at night as well as during the day. Dr. Doug Biggs and Dr. John Wormuth from the Department of Oceanography participated to define the hydrographic and biological habitat of cetaceans. Working with oceano-graphy technician Eddie Webb and graduate student Pat Ressler, Biggs used Gyre's Acoustic Doppler Current Profiler to measure currents and dropped expendable bathythermographs to obtain temperature data while underway. In addition, Gyre stopped once a day to collect hydrographic data with a conductivity-temperature-depth meter and a rosette water sampler. For biological context, John Wormuth, Dr. John Lankin (National Marine Fisheries Service, Miami), Mr. Steve Berkowitz (Carolina Coastal University), and graduate students Liz Harris, José Bersano, and Erika Vidal took trawl samples at night using a large net designed to collect discrete samples at different water depths. The samples were used to survey the amount and kinds of prey available to the whales.

In additon to bottlenose dolphins like the one pictured above, sperm whales (below) and other varieties of dolphin live permanently in the gulf. (Photo by Spencer Lynn) (Photo by Doug Biggs)   Scientist aboard the Gyre used "bigeye" binoculars to spot cetaceans in the Gulf of Mexico. (Photo by Spencer Lynn) To study the plankton that feed marine mammals, scientists use a special net to collect samples at different depths in one location. (Photo by Doug Biggs)

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Last updated January 31, 1997