Diet suspected to cause low hatch rates
The mystery of why there are dwindling numbers of farmed turtles in Cayman might be answered soon.
Scientists looking into the low hatch rates of green sea turtles at the Cayman Turtle Farm believe diet may be the problem.
Turtle numbers at the farm have dropped dramatically. In 2008, there were less than 8,000 turtles at the farm, down from 22,000 to 25,000 in 2001.
Since then, an international team of scientists and researchers has been looking at the turtles’ breeding, nutrition and health issues, including the mystery of why eggs laid at the farm were experiencing low hatch rates.
Comparing the diet and eggs of the Farm’s turtles against data found in wild turtles, the consortium of scientists from St. Matthew’s University, the University of Georgia, the University of Exeter, the University of Florida, the Department of Environment and the Cayman Turtle Farm found biochemical differences in carotenoid and vitamin levels.
Veterinarian Johanna Mejia-Fava specializes in marine animal nutrition, and has been working on formulating experimental diets to test the deficiencies.
‘Turtles are herbivores, and in the wild they eat Thalassia testudinum, the sea grass commonly known as turtle grass, and algae,’ said Mejia-Fava.
At the farm, turtles have been fed a low-protein fish food normally used for catfish.
‘In terms of why so many eggs aren’t hatching, our suspicion is coming from that area,’ she said.
The Turtle Farm’s chief scientific officer Joe Parsons added that hatchlings need an ever fuller diet with more protein.
‘In the wild they are scavenging all kinds of food all day.’
Mr. Parsons explained the fish food has been used as it is in a convenient pelletized form.
‘It’s also very difficult to collect seagrass, and the times we have collected it, the turtles didn’t seem interested in eating it,’ added Mejia-Fava.
The research is breaking new ground, as captive turtle nutrition has not been well studied.
Developing a specifically formulated, nutritionally balanced pelletized turtle food would be welcomed the world over by zoos and aquariums with captive green sea turtles.
‘Nobody in published articles has determined the nutritional requirements of turtles,’ said Mejia-Fava, noting there is plenty of research on wild turtle diet and nutrition that can be used as a cross reference.
Now, thanks to the combined efforts of donors, an important aspect of the research can now take place. Next Friday, Mejia-Fava will transport some genetic samples to Florida for the first leg of a journey that will reveal more about the eggs’ nutritional levels.
‘It was a very complicated process to arrange,’ said Mr. Parsons.
‘So many people were involved.’
Pure Air Limited and Chrissie Tomlinson Hospital donated a carbon dioxide cylinder and dry ice, enabling the study team to safely send the samples off island for testing.
‘They need to all be kept frozen or else they will perish,’ explained Mejia-Fava.
After transfer through the US Fish and Wildlife department, Mejia-Fava will make the five-hour drive to the University of Florida in Gainesville. From there, the samples will be transferred to the Mystic Aquarium & Institute for Exploration in Connecticut for testing, which will take about two to three months.
As owner of the Auto Spa, Joey Ebanks was able to fulfil his interest in supporting environmental causes on the island by paying for the testing.
‘I learned Johanna didn’t have enough funding to send the samples off for testing,’ Mr. Ebanks said. ‘I could not believe that in the government budget there was not enough funding for this particular project. How is that even possible?’
Mr. Ebanks said he thought businesses should support the project.
‘I think more businesses should step up,’ he said. ‘If we all did then we would have more than enough funding to get this research done.’
‘People can really make a difference to the research though these kinds of donations,’ said Mejia-Fava.
She noted that once the results come back, a lot of work remains in order to develop the new food, noting donations for specific aspects of the research are most welcome.
‘Once we get the results we must develop and try out various formulations, to try to balance it as close to the wild diet as possible,’ she said.