Reintroduction of green turtles has been a success in the Cayman Islands

The rate of biodiversity loss continues to accelerate, and many conservation experts are turning to the reintroduction of captive-bred animals as one potential solution to this growing crisis. In a new study from the University of Barcelona, researchers investigated the outcome of a green turtle reintroduction program that began 50 years ago in the Cayman Islands.

The analysis confirmed that the reintroduction program has been successful in establishing new green turtle populations throughout the Cayman Islands. The experts also determined that reintroduction from a captive population did not affect the health of the first generation of wild turtles. 

According to the study authors, these conclusions “show that where climate change undermines species survival, assisted colonisations could possibly be used as a conservation measure. However, decision-making must include thorough cost-benefit analyses, risk assessments, and long term scientific monitoring.”

The green turtle migratory species that is endangered worldwide. In the Cayman Islands, the green turtle population was nearly extinct by the mid-20th century, primarily due to over-harvesting.

In 1968, the Cayman Turtle Conservation and Education Centre was established in Grand Cayman. The program has helped to increase the number of nesting females over the last twenty years. Today, there is a population of between 100 and 150 adult breeding females.

The captive green turtles that were reintroduced to the Cayman Islands originated from turtles and eggs collected from different populations in the Atlantic. 

“Therefore, the first breeding individuals of the farm have genetically diverse origins, which is seen in the study,” noted study co-author Carlos Carreras. 

Study co-author Marta Pascual added that it is important to consider the genetic origins of the samples used for captive breeding in any species in order to avoid associated negative effects. “Luckily, these negative phenomena were not seen in the first generations, but we cannot rule out the option of them appearing in upcoming generations,” said Pascual.

Genetic analyses revealed that turtle populations on two islands are predominantly the result of the reintroduction project. The experts found that 79.4 percent of the turtles in Little Cayman and 90.3 percent of those in Grand Cayman were related to the adults released through the program. The researchers also determined that populations diverged quickly. 

“The random effects of the genetic drift led to the genetic differentiation of the populations, despite having originated with the same reintroduction program. Also, we did not detect any reintroduction-related adverse effect in the biological efficiency of the individuals in the new populations,” said the study authors. 

The researchers emphasized that these results were obtained with the first generation of wild offspring. With this in mind, genetic analyses should be undertaken again in the future since the harmful effects of inbreeding can appear in future generations, the experts concluded. 

The study is published in the journal Nature Communications.

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By Chrissy Sexton, Earth.com Staff Writer