The green turtles that live in Bermuda waters arrive here after hatching on distant nesting beaches and living at sea, probably for several years. After growing up on the grass flats here, these same turtles depart for foreign feeding grounds where they mature. Although the Bermuda Turtle Project (BTP) focuses on the study of green turtles in Bermuda waters, a special effort is underway to learn more about their movements away from Bermuda—into the next phase of their life cycle. This year our efforts paid off when we were able to follow a remarkable journey made by a 76 cm (30 in.) green turtle that was given the name Bermudiana.
Even before Bermudiana’s trip, clues about the life history phase that follows the extended juvenile residence in Bermuda were available from the recovery of tags put on turtles here. Every turtle handled as part of the BTP is given two tags that include reward messages.
The BTP has now had 36 turtle tags returned from foreign shores. The greatest number (24) have come from Nicaragua. The Miskito Banks on the Caribbean coast of Nicaragua are the most extensive sea grass beds in the Atlantic, and have long been known to be an important feeding ground for adult green turtles in the Caribbean. Tags have also been returned from Panama (1) in the southern Caribbean, from Cuba (8) and the Dominican Republic (1), which are along the northern perimeter of the Caribbean, and from the eastern Caribbean islands of Carriacou (Grenada) (1) and St. Lucia (1).
It seems clear from these tag returns that the Caribbean is the next destination for green turtles that grow up in Bermuda waters. But another important question is: How much control do the departing urtles have over their trip to the Caribbean? Do they simply ride ocean currents until they arrive in the Caribbean by chance, or do they know where the Caribbean is and head there directly? This is an interesting question since we believe that hatchling sea turtles make use of ocean currents, while adults appear to be in complete control of their migratory travels.
The technology that we chose to answer this question is a radio transmitter that transmits to ARGOS satellites orbiting the earth. Several daily transmissions allow us to monitor the location and diving behavior of turtles far out at sea. The most interesting track was that of Bermudiana, who we captured on August 5, 1998, about 3 miles west of Daniels Head, Bermuda. She was fitted with a transmitter and released at the point of capture. Bermudiana stayed in Bermuda waters for about two weeks and then struck out to the south-southwest. She traveled in a nearly straight line, covering the distance between Bermuda and the Dominican Republic, about 1,500 km, in one month! Bermudiana arrived in the Caribbean at the same time as Hurricane Georges. There is no way to know if the storm affected her travel, but we can see a major turn to the northwest and then again to the southwest. Bermudiana may have been looking for a site to take up residence in the Greater Antilles, but our tag return data suggest that she may have been looking for a passage into the Caribbean Sea. She was close to the Windward Passage, between Cuba and Hispaniola, but never made it there. The transmitted data indicate that she was captured on September 26, 1998, on the eastern tip of Cuba near the town of Baracoa. She most likely was killed for food. Her capture illustrates the dangers that green turtles still face throughout most of their range and points to the need for international cooperation in the protection of sea turtles.
The Bermuda Turtle Project is dedicated to improving the survival status of green turtles in the Caribbean — a goal which will require a long-term, regional conservation effort. BTP is a collaborative research project of the Bermuda Aquarium, Museum and Zoo and Caribbean Conservation Corporation, with the assistance of the Bermuda Division of Fisheries. To provide more information about the Bermuda Turtle Project, CCC and BAMZ are developing a web site for the project that will be added to CCC’s website before the end of 1998.
Peter Meylan, Ph.D. is a Professor at Eckerd College, while Anne Meylan, Ph.D. is on CCC’s Scientific Advisory Committee and is a Researcher with the Florida Marine Research Institute.