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(Grand Cayman, 2 Aug 2011) -- Testament to the success of the breeding program at the Cayman Turtle Centre: Island Wildlife Encounter, earlier last month, 11 green sea turtles laid almost 900 eggs on the beach in one night.
“We are very excited with the activity we saw on this one night; and hope that it is indicative of future breeding successes. Our team of experts continue to develop and try new methods and conduct scientific research that will boost hatch rates as well,” explains Mr. Tim Adam, Managing Director.
While this is a very impressive number of eggs, how many of them are likely to hatch? To answer that question, we can obtain clues from each female’s age, origin, and previous year’s hatch success, explained Dr. Walter Mustin, Chief Research Officer of the Turtle Centre and an expert in hatchery management and aquaculture nutrition.
“Records show that one of these turtles has laid 88 nests over the past 19 years with 32% hatch success and we have high expectations for her eggs this year.
In contrast, these are the first eggs that have ever been laid by four of the females. Others in this group have nested before with none of their eggs hatching” he adds.
One of the reasons may be that these breeders are not quite old enough to lay viable eggs. Green sea turtles in the wild reach sexual maturity only when they are 20-30 years old. Some of our females are laying eggs at the early age of eight years, which is a result of the ample food and protein provided them.
After Hurricane Michelle, over 300 relatively young turtles were placed in the breeder pond to replace the 75% of the breeder herd that was lost to the storm. Now, these replacement breeders are 10-15 years old, young by biological standards. Eventually, I expect this younger population sector to come to maturity and produce more and more eggs that actually hatch,” Dr. Mustin explained.
Meanwhile, research aimed at improving sea turtle hatch rates continues at the Cayman Turtle Centre on multiple fronts. A custom breeder diet is being formulated that more accurately reflects and mimics the nutritional composition of the green sea turtle’s wild diet (turtle grass, liver sponge, and marine algae).
“The causes of infertility are being examined. All eggs that do not hatch are staged to determine the state of fertility and/or development. New incubation techniques that reduce early hatching mortality are also being implemented,” Dr. Mustin explained.
The ultimate goal of the Cayman Turtle Centre team is to be able to release more and more green sea turtles.
“As our hatch rates improve, so will our ability to release greater numbers to the wild. We know from tagging studies on turtles released from the Cayman Turtle Centre that our released turtles are not only surviving and travelling throughout the Caribbean, but that turtles that we released in the 1980s are now sexually mature and returning to Cayman beaches to lay their own eggs.
Of the 30-60 green sea turtles that the Department of Environment estimates visited our beaches last season to lay eggs, at least five of them were released as yearlings from the Cayman Turtle Centre some 25 years earlier.”
Turtle Centre Managing Director Tim Adam said he was very pleased by the successful nesting, which showed how well the breeding program was advancing. “The efforts of Dr. Mustin and his staff and their commitment to improving hatch rates will ensure that as our females reach breeding age they will be able to lay greater numbers of viable eggs. Their work is vital to our mission to promote conservation of the green sea turtle.”