Results of 1994 and 1995 Migration-Tracking
of Florida Green Turtles
During the 1994 sea turtle nesting season, researchers
Barbara Schroeder with the Florida Department of Environmental Protection's
Marine Research Institute, Dr. Llewellyn Ehrhart with the University of
Central Florida and George Balazs with the National Marine Fisheries Service
attached satellite transmitters to three green turtles that nested in the
Archie Carr National Wildlife Refuge. The three turtles — named Honu, Fairly
and Keya — became part of a unique research project designed to help discover
the unknown migratory patterns of green turtles nesting in Florida.
After attaching the transmitters, researchers studied
locational data sent back through the Argos satellite system. At the 1995
Sea Turtle Symposium in Hilton Head, South Carolina, the preliminary findings
were presented by Schroeder in a paper coauthored by Ehrhart and Balazs.
The following short summaries of each turtles' movements are based on data
presented at the symposium:
Fairly - Tag #22127
Tagged on July 23, 1994, Fairly's transmitter sent signals until October
15. On August 13, she was seen nesting again in the Archie Carr Refuge
(green turtles are known to nest 3 or 4 times aseason). After having nested
again, signals located her off the coast of Ft. Lauderdale. After another
13 days, she had made it to an area off the lower Florida Keys known as
Coffins Patch Reef, where she stayed approximately 50 days until signals
were no longer received. The habitat in this area is characterized as patch
reef with fragmented seagrass meadow.
Keya - Tag #22128
Tagged on July 22, signals were received from Keya until late October.
From July 22 through Sept. 5, all of Keya's signals were sent from the
vicinity of the Archie Carr Refuge. On Sept. 8, her signal began to illustrate
a southward migration, and by Sept. 16 she had reached the coastline near
Key Largo, Florida. Her final signal, received Oct. 21, showed her stationary
off the Marquesas Keys located at the southern tip of the Florida Keys.
The habitat here is also characterized as patch reef and seagrass meadow.
NOTE: Keya was seen nesting again on 13 August, 2000!
Honu - Tag #22129
Tagged on July 21, Honu's transmitter did not function long enough
to document any movement away from her nesting beach. Signals ceased after
30 days, during which time she stayed in the immediate vicinity. The last
signal was received Sept. 9, 1994.
After the study, the research team made a preliminary
hypothesis that Florida green turtles utilize reefs and seagrass meadows
around the Florida Keys as their primary feeding grounds. However, because
of the short duration in which signals were received, more study was needed.
A similar experiment was conducted during the 1995 nesting
season. This time, the turtles' movements were tracked for longer periods
of time, and the results provided new insight into the migration of Florida
green turtles. Some of the turtles tracked during 1995 followed a similar
course toward the Florida Keys. However, at least one green turtle migrated
to the Bahamas and travelled throughout the islands until her transmitter
stopped working.
CCC was very interested in seeing this research continue and tracked four green sea turtles in 1996 with the assistance of Snapper, Inc., the Educational Foundation of America, the Geraldine R. Dodge Foundation, the Blue Planet Foundation, University of Central Florida, and the Florida Department of Environmental Protection. CCC would like to thank Barbara Schroeder at the National Marine Fisheries Service, Andrea Mosier at the Florida Marine Research Institute and Dr. Llewellyn Ehrhart and his students at the University of Central Florida for funding, tagging the sea turtles and providing the location maps. See the results of the 1996 tracking.
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Results of 1995 Migration-Tracking Research in the Caribbean
The new technology of satellite telemetry has made it
possible for researchers to study effectively for the first time the migratory
habits of male green turtles in the Caribbean.
Because males do not leave the water (except occasionally
-- to chase a fleeing female through the surfline!), they don't readily
lend themselves to observation, and they are rarely tagged. Consequently,
next to nothing is known about their movements and biology.
Tagging studies at Tortuguero conducted by CCC have produced
a large and valuable body of data about the reproductive biology and migrations
of the female green turtle. However,rough and turbid sea conditions throughout
most of the nesting season have discouraged investigations in the waters
off the nesting beach. Until recently, most of the information on Tortuguero
males has been gleaned by Costa Rican scientists during visits to the turtle
slaughterhouse in Limon.
Since 1990, CCC associates Peter and Anne Meylan have
been studying the green turtles that pass seasonally through the waters
of Bocas del Toro Province, Panama, approximately 150 miles southeast of
Tortuguero. Locals in Bocas have traditionally fished for green turtles
for centuries. The timing of the appearance of turtles in Bocas, the recovery
of Tortuguero tags in Bocas and of Bocas tags in Tortuguero, and genetic
data, all suggest that the green turtles the Meylans catch each year are
members of the Tortuguero population.
The migrants are caught in large-mesh tangle nets, measured,
tagged and released. Although there have been more than a dozen long-distance
recoveries of turtles tagged in Bocas, the actual routes and schedules
of migrations of the turtles tagged there have remained unknown.
In July 1995, two breeding males captured in Bocas were
outfitted with satellite transmitters. The ST6 units, made by Telonics, were fiberglassed directly onto the back of the carapace, behind the head, where the unit's small flexible antenna can break the surface and transmit when the turtle comes up to breathe. The transmitters send information to passing satellites about the position of the turtle,
the number of dives during the last 12 hours, the length of the last dive,
and the temperature. The satellite re-transmits the data to France, where
it is relayed to the United States and can be accessed by computer. The
coordinates can then be plotted on maps, and the position and travel route
of the turtle can be determined.
Analysis of the satellite data suggests that these two
males did not behave as researchers expected. Current life history models
predicted that they would proceed to Tortuguero with the females, and remain
there for mating purposes in the near shore waters. They would eventually
head back to their resident feeding grounds, which in the case of migrants
captured in Panama, would be in the direction of South America. Neither
turtle followed the model. The Meylans are now evaluating other hypotheses
to explain the movements. The plotted movements of both turtles can be
seen on the this map.
One of the turtle's (the blue track on the map) transmitter continued to send signals
until around the end of September, when data began showing no more dives
below the water's surface. Eventually, it was determined that the signals
were coming from a remote section of the Panama coast, where extensive
net fishing for turtles is known to occur. After a very interesting search,
the transmitter was recovered from the fisherman who had caught the turtle,
and it was confirmed that the turtle had been butchered.
The other turtle (the red track on the map) was tracked until the end of November.
After moving a short distance offshore, the turtle moved north and seemed
to circle off the Costa Rican coast near Tortuguero --probably searching
for females. Eventually, the turtle traveled still further north to the
well-known green turtle feeding grounds at the Miskito Cays off Nicaragua.
The project was funded last year by the Wildlife Conservation
Society; technical support was provided by the U.S. Fish and Wildlife Service.
With the help of CCC, the Meylans are working to plan and fund additional
research to be conducted later this year on turtles around Bermuda. As the
project proceeds, the migration data will be posted and regularly updated
on a map at this web site. We invite you to check back regularly to watch
the movements of these and other turtles being tracked by satellite.
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