Every summer our seas are just about warm enough for turtles to come in after their favourite food – jellyfish!
We’ve had all, but one of the 7 marine turtle species appear in UK waters. Most turtles visiting the UK are out of their comfort zone temperature-wise, as they’re reptiles, most of which take on the temperature of their surroundings rather than using energy to generate their own body heat. The leatherback turtle (Dermochelys coriacea), however, as well as being the world’s largest turtle (average 2.5m long; 250-700kg) is capable of maintaining a body temperature higher than that of its surroundings.
They use a counter-current exchange system to do this as well as having a large amount of oils in their body. This opens up more areas of sea with plenty more jellies and jelly-type organisms to hunt and means they’re the most widely distributed of the marine turtles. Another major difference they exhibit to other marine turtles can be seen in their name – Leatherbacks. Well named – they are covered in a leathery skin, instead of a hardened shell.
Leatherbacks are also capable of heading down into the depths to hunt deep sea jellies too and can dive well over 1km. For this they have developed adaptations to help the dive, but the dive itself might also be an adaptation to help cope with very warm temperatures in tropical waters. They use the downwards-facing spines, which line their throat to keep hold of their prey once encountered. Like many turtles, they do a good job of keeping down jelly numbers, so they’re a fundamental link in marine ecosystems and turtles and their ancestors have been doing this for over 100 million yrs.
Tragically, leatherback populations have undergone major historic and ongoing declines. Their biology doesn’t help them recover quickly from loss; females only reaching maturity at 25-30yrs of age. Avoiding multiple threats, they can live on average to 45-50 years, but are capable of living a lot longer. A breeding female will return to land (every 2-3 yrs) to lay her own eggs, repeatedly dragging her enormous weight up steep sandy beaches, night after night.
It was during the breeding season on Trinidad in 2007 that one of our team spent one of her most memorable nights ever, surrounded by huge reptiles digging and laying precious eggs. She had been lucky enough to be able to join the local university’s Biological Society efforts to help boost the numbers of volunteers, monitoring and warding off disturbance during the months when most breeding took place. Breeding time is a particular focus for conservation, as, of course, eggs are the next generation, but they’re also packed with nutrition for a growing foetus and so a prize for thieves. The local villagers realised this was a problem, as well as disturbance, scaring off the mothers and even poaching the adults for meat, so they began to go out every night for months at a time to protect these seasonal visitors. This, became part of a more established effort across Trinidad and Tobago turtle beaches, to become the Turtle Village Trust, attracting more help, funding via the partners and through tourism permits and have been host to a BBC film crew with David Attenborough in tow for Blue Planet II!!
Despite this enormous (ongoing) and largely successful undertaking, the babies we also saw hatching that night might never see their 1st birthday. In fact, the percentage survival rate of those babies which reach that yearling point is thought to be as little as 1 in every 1,000.
Many turtle records from around the UK come from strandings. Seeing a living turtle in UK waters is difficult, as often it’s only a head that can be seen when at the surface. This is something we hope those using the waters around the Welsh coast are keeping an eye out on, as well as rafting birds, seals and cetaceans and know to act accordingly via our Marine Code.
Strandings have been reported of various turtle species over the years, but by far the most famous and compelling is that of the male leatherback turtle found at Harlech in September 1988. Famous due to its record-breaking size (900kg/2000lbs and nearly 3metres in length) and age (estimated at >100yrs), compelling due to its human-helped death (entanglement and anecdotal reports of marine litter ingestion).
As part of our Marine Memories Project our Living Seas Team spoke to Mike Alexander, the warden at the time, who was called out to the record-breaking stranding. Mike recalls locals describing the leatherback as “a monster on the beach” and being “bigger than a cow…a bit like a Volkswagen car!”. It was having transported the body down to Cardiff, to the National Museum of Wales, whilst using a crane to move the turtle, that the team began to realise just how big it was! The alarm bells went off – the specimen exceeded the legal weight that the crane could lift! It was at that point that they realised they “probably had the biggest turtle that had ever been recorded”.
The rest in a sense is history – Mike explained how a team from the USA travelled to Cardiff to help with the autopsy, indicating just how important the find was! The record-breaking specimen is now exhibited in the National Museum of Wales.
The Harlech male would have spent his entire life at sea, not needing to return to land to lay eggs, like the females. Turtles are mainly solitary ocean roamers and protection is difficult for mobile species, let alone ones which cross oceans and only aggregate to breed. Hazards are numerous for both the young and adults (by catch, marine litter, light pollution, predation, boat strikes, disturbance, etc). Globally, they are listed on the IUCN Red list as vulnerable (this is a relatively recent increase from being Critically Endangered and that’s due to Conservation efforts), but this doesn’t show the various pockets around the world where their status is much worse and they are struggling (they are critically endangered in the Pacific and Southwest Atlantic). In fact, due to egg collection, they have become locally extinct in Malasia.
Leatherbacks love their jellies and guess what looks like a jelly in our seas, but can, instead cause real damage and death to an animal which has ingested it - a plastic bag and balloons. What can you do? Question whether you need that bag or balloon for a start. Can you take your own containers to fill/bags to use, can you celebrate/mark a day without balloons at all, can you urge companies, councils etc to ban balloon releases.
Why not go a step further (plastics can also be ingested as microparticles or turtles can be entangled by ghost gear or can rings) and join in with the Marine Conservation Society’s plastic-free July, or go for Friends of the Earth’s Plastic-free Friday. Take a bag with you the next and every time you head to the beach or just around and abouts to do a #2MinuteBeachClean pick up #5ThingsClear.
Leatherbacks have lost numbers due to by-catch. Across the world they’re caught in nets, on lines etc. as the fishing industries catch our food. What can you do? - As with dolphin-friendly tuna, choosing sustainably caught seafood (seafood which has been caught in a manner which reduces the chances of turtles being caught) is a must. Always keep an eye out in the supermarkets, ask at restaurants and fishmongers and have a nosy here to keep up-to-date.
Increased storms and rising sea levels means nesting beaches can be ravaged, changing ocean currents can alter availability of food and increased temperatures on nesting beaches can affect the sex ratio of the young (higher nest temperatures produce female hatchlings) or even kill before hatching. What can you do? - As with everything, reducing your carbon footprint in as many ways as possible, will help our seas and planet, altogether. You can check the carbon footprint of your seafood intake by using the WWF Finprint checker.
Boat strikes are a common threat to turtles, causing damage which can seriously affect their survival or even death. What can you do? Get to know your local Marine Code (scroll to map at bottom and click on your local code) and, please, spread the word. The more people who know about it, the more people likely to keep to it and the more people looking out for our wildlife. UK-wide there’s also the Turtle code.
What else can you do? You can use your voice: join campaigns, sign petitions for increased protected areas and also use your voice to spread the word. Choose reef-friendly sunscreen; on holiday NEVER buy turtle products, DO source environmentally-friendly hotels, trips and food; Learn how to help if you ever come across a live stranded turtle or know who to tell if you find a dead one ashore; report any sightings of Turtles in UK waters; contribute your memories of turtles in Welsh waters to our Marine Memories Project.
Ending on some better news, with all the conservation efforts and protections (Protected in the UK by Wildlife and Countryside Act, Habitats Directive in Europe and CITES) now in place, the Atlantic population of leatherbacks, which connects our turtles with those witnessed on Trinidad, is increasing. Let’s all help to keep it that way.