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Individual study: Returns of green turtles Chelonia mydas in a restocking experiment on Bermuda

Published source details

Burnett-Herkes J. (1974) Returns of green sea turtles (Chelonia mydas Linnaeus) tagged at Bermuda. Biological Conservation, 6, 307-308


As part of a green turtle Chelonia mydas restocking experiment in Bermuda, 89, 2-year-old turtles (captive-reared from eggs) were transported from the Turtle Research Station of the Caribbean Conservation Corporation, Tortuguera, Costa Rica, between 1967 and 1971. These turtles were tagged in an attempt to assess the success of the releases through any subsequent recoveries of these individuals.

Tagging commenced in 1969, all 89 captive-reared individuals were tagged (monel poultry wing tag fastened to the rear of the fore flipper close to the body) prior to release. An additional 19 immature wild turtles (handed in by local fishermen as they were below the minimum legal size limit of 18 kg) were likewise tagged. Between 1967 and 1971, 79 tagged turtles were released from the north shore and 29 from the south shore of Bermuda.

Recoveries of tagged turtles in Bermuda comprised only north shore releases: 16 returned, two of these twice. Of the nine measured, three had grown well: two were wild caught (released 12 and 17 months earlier), the other captive-reared released 27 months earlier, (average increase in carapace length 3.7 mm/month). The remaining six averaged less than 0.3 mm/month growth but had been at sea for less than 10 months. The distance travelled by these turtles from point of release to point of recapture averaged 3.5 km (range a few hundred metres to 13.9 km); distance travelled was not correlated with number of days since release.
The only recovery from a south shore release was from the coast of Venezuela (Peninsula de Paraguana, Falcon State), a distance of 2,315 km. This was a captive-reared individual recovered 10 months (293 days) after release from Bermuda. At the time of release it weighed 3.86 kg and had a straight-line carapace length of 304 mm; unfortunately no measurements were made on recapture in Venezuela. The two captive-reared recoveries add to evidence of the ability of captive-reared turtles to survive over long periods in the wild and travel over long distances.
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