Cayman farm turtles reveal hope for biodiversity loss

| 30/03/2022 | 21 Comments
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(CNS): A collaborative research project into the green turtles that were released into the wild by what was at the time the Cayman Turtle Farm has shown that the accelerating biodiversity loss from global warming and other human activity could in some circumstances be assisted by the reintroduction of captive-bred animals.

The results, published in the journal Nature Communications, show the project here was successful in establishing new turtle populations that did not affect the fitness of wild turtles.

The study was led by experts Marta Pascual and Carlos Carreras, members of the Laboratory of Evolutionary Genetics of the Faculty of Biology and the Biodiversity Research Institute of the University of Barcelona (IRBio). The researchers analysed the impact of the original turtle farm programme that began 50 years ago and concluded that “where climate change undermines species survival, assisted colonisations could possibly be used as a conservation measure”.

But the scientists warned that such programmes must include thorough cost-benefit analyses, risk assessments, and long-term scientific monitoring. The study highlighted the things that need to be considered, including the risks of releasing captive-bred animals into the wild, including infectious diseases and the potential dangers of inbreeding.

Experts from the University of Exeter and the Cayman Islands Department of Environment also worked on the study, which could have implications for the future of other endangered species. The research found that the turtle release has helped to increase the number of nesting females over the last twenty years and Cayman now has a population of between 100 and 150 adult breeding females nesting on the beaches.

The captive green turtle population at the farm originated from adult and juvenile samples and from eggs collected from different and genetically diverse populations in the Atlantic. Pascual said the genetic origins for captive breeding in any species is important 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,” she said relating to the turtles now breeding in local waters that came from the farm.

The researchers learned that 79.4% of the turtles in Little Cayman and 90.3% of those in Grand Cayman were related to the adults released in the early decades of the turtle farm programme and that the 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 programme. Also, we did not detect any reintroduction-related adverse effect in the biological efficiency of the individuals in the new populations,” noted the researchers.

The scientists said the relative success of the turtle farm programme has shed light on using captive bred programmes for other long-lived, migratory and philopatric species when the degradation of the habitat endangers their survival, but it should not be a matter of first resort

For sea turtles, important considerations for captive breeding include animal husbandry and welfare concerns, the potential for disease transfer through the release of animals from an intensive rearing facility into the wild, high costs, and apparently low rates of recruitment into wild nesting populations.

The authors suggest that ex situ strategies should not replace but aid in situ conservation, and the latter should be considered as a conservation management priority before resorting to complicated, costly and controversial ex situ conservation strategies.

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Category: Marine Environment, Science & Nature

Comments (21)

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  1. Gaz Trognome says:

    Delicious and their young are just perfect as cheeky appetiser.

  2. Guido Marsupio says:

    Please explain, scientists, if the turtles that were captured for breeding at the farm came from the wild Atlantic population, how do you know that the ones you found recently in Little and Grand are from the farm and not from those same wild Atlantic populations in the first place?

    • Anonymous says:

      Guido Marsupio – Eggs, Guido, eggs. This doesn’t answer your question, perhaps the scientists will, but they must know why they can say that – DNA tests perhaps?

      The “Atlantic” areas referenced in the article as the source of harvested eggs at the beginning of the program is actually the Caribbean Coast of Nicaragua (mostly). I recall that info being published in the late 1960s when Mariculture was starting this program. The majority of original eggs came from Western Caribbean beaches and apparently the turtles originated from the Farm’s releases.

      To many North Americans and European the Caribbean Sea is actually the Atlantic! Let’s not split hairs and try to connect all the seas now.

    • Anonymous says:

      Hi – Genetics. Because within the Atlantic there are many genetic sub-populations because the turtles return to their same ‘home beaches’ to nest (and mate). Meaning that Honduras, Nicaragua, Florida, Barbados, Ascension Island, Senegal (West Africa), etc., all have their own (nesting) population of ‘Atlantic’ turtles. And the scientists can tell these turtles apart based on their genetics.

      Scientists have taken the genetic profile of turtles at various other (nesting) populations around the Caribbean (and the world). So the scientists would have taken the genetics of the turtles still in the turtle farm – so known Farm stock and descendents only of Farm stock – and genetics of the local nesting turtles (from the eggs in the nests and some of the mothers nesting). Then it compared them. That genetic comparison can show how related the animals are. Like a human genetic test saying the person has X% African ancestry. In this case 80%-90% Farm ancestry. Since the Farm did not get any founder stock from the Cayman Islands (I think) any local turtles with genetics that match the Farm had to come from the Farm. And since the turtles return to their native beaches (generally; they are probably only 99.99% restricted, especially over evolutionary time) any local nesting turtles with Farm genetics came from the Farm (or at least their parents did). Further, any locally nesting turtles with genetics that show say partial Ascension Island or Nicaragua are most likely going to be from the Farm since that’s (IIRC) where they got some of their founder stock from. (It would be unlikely in the extreme for those two genetic nesting populations to mix in the wild.) And the Farm descendents (in the Farm) will (probably) not show pure strain of country X since they are interbred in the Farm tank. (Hypothetically an Ascension mother and an Ascension father could produce a baby in the Farm showing pure Ascension on the genetic test.)

      This only works for animals that have high site fidelity in some way. Like turtles returning to their nesting beaches. (Or, in the case of the Farm releases, after 20 years getting back to Little Cayman and saying that’s close enough to call ‘home beach’ from now on.) Its how scientists around the world do it, for those species it works for. For example previous work showed that the juvenile hawksbills in Little Cayman came (a lot) from Cuban nesting beaches.

      And if anyone asks about the males – since the nesting turtles are obviously only females – you probably can’t prove they return to their hatch beach but every year people are posting pictures of mating turtles around Cayman and if the males were not staying true to their ‘home’ nesting population then the genetics would be a lot more mixed up than they are. So since it is possible for scientists to say that a particular turtle genetics represents location X then that means the males return as well as the females.

      Turtles are pretty amazing.

  3. Anonymous says:

    The Turtle farm is just another get rich scheme for certain people.

  4. Anonymous says:

    How are the hawksbills and loggerheads in our waters and laying eggs on our beaches related to the green sea turtles raised in tight pens for meat consumption at the farm? How hard do we need to squint to arrive at that alternative reality?

    • Anonymous says:

      31 @ 2:00pm – Says you! The article specifies green turtles, if you read past the first 5 words! Don’t like reading?

      CTC/CTF/BB/Mariculture released a few kinds (perhaps except Kemps) over the years, obviously including greens.

      The scientific proof (although obvious, in my opinion) is now in hand but seems like you don’t like science.

      So, what about locally-laying hawksbills and loggerheads? I guess that’s nature. You familiar with that?

    • Anonymous says:

      They are not and no one is saying they are. In fact they would make a handy comparison for the researchers precisely because they have not been farmed & released here.
      – Greens: population recovering with mostly Farm input
      – Loggerheads: population recovering with no Farm input
      – Hawksbills: population just beginning recovery, no Farm input
      – Leatherbacks: no local nesting population. (I’ll leave it to those older than me to comment if thy ever heard of nesting leatherbacks here or not.)
      – Conclusion: farming (or similar) can help but may not be necessary so deciding to farm/release or not should be based on other factors.

      Please lets not argue about those other factors today ;-). Lets just focus on the neat science that was done.

  5. Anonymous says:

    The article has a rather negative tone considering the unmitigated success that the actual evidence shows. It seems more like an advertisement for the future employment of turtle scientists without whom nothing can be safely accomplished. Keep on keeping on Cayman. What you have done clearly worked.

    • Anonymous says:

      The Cayman Turtle Farm is not an ecological re-wilding program like it may have partially been at some scale during the 1968-80s Mariculture period. It’s now (at minimum) a heavily-subsidised meat farm that encourages and perpetuates generations of consumption of endangered species as some kind of misplaced “birth right”. I am embarrassed as a Caymanian that this place wasn’t closed after H. Michelle. Even then, it was long past time. The MP from WBW had his own reasons for keeping this going with all his handpicked, and we can only guess what the motivating racket is beyond the thefts that routinely emerge. One day someone will pull back the curtain on what’s really going on there, and where tens of millions goes to disappear, but I think we already know it’s unlikely to be something we will be proud of.

  6. Anonymous says:

    I’ve always supported all turtle preservation and it’s quite encouraging to hear the news that a high percentage of wild turtles on GC and LC now are directly related to the decades-old turtle release programs. But is that any surprise?

    Even primary schools children now know (or should) that turtles return to the beaches on which they were hatched. So it’s no great surprise that locally hatched turtles released from local beaches are the forefathers of the local turtles now.

    Wonder how much public funds our CIG/DoE “granted” the Universities of Exeter and Barcelona to “learn” that??

    I doubt those uni’s paid for the costs of those studies for the sake of science!

    • Anonymous says:

      Yes, for sure lots of descendants of the 1968-1980s Mariculture Ltd releases…back when there were regular releases and published science. Trying to feign redeeming conservation relevance now for work logged 40 years ago, continues to fail the basic sniff test.

  7. Anonymous says:

    Apart from filling local plates what benefit has the super expensive farming of Turtle had on the declining marine environment?

  8. Anonymous says:

    Nothing tastes better than inbred turtle stew.

  9. Anonymous says:

    It only costs us $5mln per turtle!

    • Anonymous says:

      The people that destroy nesting habitat should have to pay a tax to support the farm. And yes Im serious.

      • Anonymous says:

        The turtles are raised for food, not to replenish the ocean populations. The abattoir was created so that our poachers would be encouraged to buy subsidized turtle meat for less than big ag frozen chicken. It has nothing to do with habitat destruction, which has been minimal. Human interference and lighting remains so much of a problem that DoE can’t mark the nests like elsewhere, and often digs up the clutch for relocation to the incubator…at the abattoir!

        • Anonymous says:

          Utter lies. The DOE do not dig up nests and put them in an incubator anywhere let alone at the turtle farm. They only move nests higher up the beach if they are in danger of being flooded by storm surge. Stop spreading lies.

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