The relatively small numbers of turtles remaining in the world is shocking, says JOHN CHRISTOPHER FINE, but then, they face so many challenges. How can divers help?
“We ate turtles. They were our food in Cuba. When we came to Florida we caught them and ate them. When laws were passed to protect them, we still caught them and ate them. Rich people had food – we didn’t,” I was told by a Cuban-American.
He had no remorse about killing marine turtles for food. That’s how his family had lived in Cuba and how they lived when political situations changed and they migrated to the Florida Keys. People still eat sea turtles in various forms, as soup or as meat.
Many more turtles are killed by boats, caught in nets, entangled in fishermen’s lines and by ingesting plastic waste. With rampant human population growth, building on beach-fronts and insidious pollution, seagrasses are being killed, eliminated from shallow reaches of the oceans and depriving turtles of their natural food source.
Billionaires with ocean-front mansions, rarely inhabited because they are part-time dwellings, keep security lights on as well as patio and house lights during turtle-nesting season. Female turtles coming ashore to make nests and lay their eggs get disoriented, abort their eggs and swim back to sea.
For the convenience of tourists, beach-front cities engage in multi-million dollar beach “renourishment” projects. Sand from deeper ocean areas is pumped onto beach areas. Not only do these noisy projects take place during turtle-nesting season but they often pile sand in berms that turtles cannot cross to nest beyond the high-tide line. Nests are washed away.
History relates the importance of turtles as food during the first sorties of conquerors in the New World. Turtles are air-breathing reptiles. They would be caught, tied on board ships on their backs and kept alive until consumed.
South Florida is host to five of the seven species of marine turtles. They are not normally territorial in the Gulf Stream waters of the east coast but migrate there to mate – then for the females to struggle ashore and lay their eggs on the beaches.
Loggerhead, green, hawksbill, leatherback and occasionally one of the 9,000 surviving Kemp’s ridley turtles visit. Of the hatchlings that dig their way out of the nests, fewer than 1% survive to adulthood.
Ben Galemmo, captain of Scuba Tyme III, a dive-charter boat out of Boynton Beach, summarises it best by praising Florida Wildlife Commission’s turtle-monitoring programmes: “Enforcing turtle-protection laws is tantamount to helping to ensure their survival,” he says.
Ben is a veteran scuba diver who anticipates sharing the wonders he sees every season off the state’s beaches with other divers, as turtles return to his native waters.
Volunteers have started beach patrols. Tapes and stakes in hand, they mark and cordon off turtle-nests. It’s not an easy pre-dawn job. When one volunteer asked beach-goers to remove their umbrella and lawn-chairs from on top of a marked nest, she was roundly cursed.
It took a reminder that their action was against the law, and that the police would have to be called, to get these belligerent people to move off the nest.
Nests are invaded by feral dogs, raccoons, skunks and other predators. Poachers digging up eggs to sell as delicacies account for many losses.
Temperature sex determinant
Hot chicks, cool dudes: turtles are temperature sex determinant, which means that when temperatures are above 31°C in the nests, the hatchlings will be female. Temperatures below 27.7°C mean that the hatchlings will be male, and temperatures in-between mean mixed sexes.
Ocean-dredged sand is a different colour to coral-beach sand. Dark sand means hotter temperatures, as you know when you walk barefoot. You might be able to tolerate stepping on white cement, but step on black asphalt and it is hotter.
Pump dark sand onto beaches, and the temperatures in nests go up. So stop playing with nature.
There are reckoned to be 50,000 loggerheads, 35,000 leatherbacks, 25,000 hawksbill and 90,000 green turtles left in the world. Olive ridleys are the most numerous species, with estimates of 800,000, while Australia’s flatbacks number 21,000. Florida’s population has topped 22 million people.
Hope? Well perhaps, if we stop eating them, running them over, throwing away plastic bags and catching them in ghost-nets and lines. Scuba divers can play their part by looking but never touching.
It is turtle-mating season right now off Florida’s shores. Vast numbers of turtles will migrate hundreds or even thousands of miles to arrive off the beaches where they hatched out. Why? Because they can’t do otherwise. How? It is only recently that science figured that out.
Long ago I found a dead turtle hatchling on the beach. It didn’t make it to the ocean and died when day broke and the sun scorched it. I put the hatchling in a cup of water, took a magnet and used it to swirl the turtle around in the cup.
I could do that because magnetic crystals in the turtle’s brain are imprinted at birth. What a miracle of life! The turtle hatches out, drifts in vast oceans for at least five years when it can reach sexual maturity, then returns to where it hatched out.
It’s enough to enhance my life just knowing that they exist.
John Christopher Fine is a marine biologist and and specialist in maritime affairs. He is a Master Scuba Instructor, Instructor Trainer and the author of some 25 fiction and non-fiction books on a wide range of themes, most recently Hunt For Gold.
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