I was cruising along the north wall on a recent dive with my children, Jessica and Alexander, near one of my favorite locations called Hammerhead Hill. Up ahead, in sixty feet of water, I saw a flash of living colour; three queen angelfish were working on the bright, fresh scar in a sponge caused by a feeding hawksbill turtle.
A photographer’s treasure trove indeed! I fired off several shots before the turtle turned and moved slowly away. We pulled back as it returned shortly to resume its feast.
After the dive Jessica asked me why the turtle was eating the sponge. Didn’t they eat sea grass? I explained that most people are familiar with the green turtles that are easily kept in captivity and are raised at the Turtle Centre. Being carnivorous, the hawksbill eats mostly sponges which comprise about 90 per cent of its diet in the Caribbean. Hawksbills also consume some gorgonians, with the occasional crab, lobster or juvenile conch thrown in.
The large loggerheads also feed on crustaceans and conchs but not sponges. In contrast, green turtles are mostly herbivorous and so are easily raised in a farming situation. This is why we see more hawksbill turtles on the reefs around the Cayman Islands than green turtles.
The hawksbill turtle, Eretmochelys imbricata, was once the most sought after turtle species for its heart-shaped shell, beautifully mottled brown, yellow and black. The shields of the carapace are imbricated or overlapping like tiles on a roof. The head is small with a hawk-like beak that it uses to cut into the structure of sponges.
The hawksbill has been hunted by man throughout its circum tropical range for its beautiful shell. This overexploitation has reduced the Caribbean population to just 10 per cent of pre-exploitation levels, though trade in tortoiseshell today is now banned by international treaty, greatly reducing the marketplace for tortoiseshell hairclips.
Reproduction is slow, as they nest once every three years. While conducting my PhD work out of the University of the West Indies’ Port Royal Marine Laboratory off Kingston, Jamaica in the early 1980s, one of my most rewarding studies I conducted was initiating a “head starting” programme for hawksbills. We would locate their nests on the offshore cays, and when the three inch long hatchlings were ready to emerge, they were taken to the lab, fed a mixed diet of fish and squid and growth rates were studied.
After six months at an average size of four pounds, they were all tagged and released. At that time hawksbills were aggressively hunted in Jamaica by spear fishermen and with specially designed turtle nets.
Once they have spent up to three years at sea after hatching, the juvenile turtles hide amongst the fronds of Sargasso weed, feeding and growing slowly as they evade predators. Then the juveniles return to the coral reef environment and take advantage of a mixed diet of invertebrates, fish and algae, before eating more sponges as they grow larger.
Their average size around Cayman reefs is 15 – 50 Pounds, but they grow to 150 pounds and live for fifty years. In Cayman, as in most countries, the hawksbill is protected, and the results are there for all to see. On nearly every dive in Cayman, I see up three different hawksbills. Nowadays a living hawksbill is worth far more to small island economies than a preserved shell on a wall or a turtle steak on a plate.
I was recently diving with a group of visiting artists from a group called Artists For Conservation whose main goal after a visit to the Turtle Centre was to see wild turtles on the reef. I said that should not be a problem and we encountered hawksbills in the first few minutes of the first dive.
Hawksbills and green turtles have become far more valuable to the Cayman Islands than just as turtle meat. Visitors and diving residents like me really enjoy the encounters with cooperative hawksbills. To attach a dollar value to these creatures is now essential, just as we attach dollar values to Nassau groupers, stingrays, sharks and marlins. Lawmakers must appreciate the value of living marine resources to this country’s economy.
Each wild turtle here generates tens of thousands of dollars of income for the Cayman Islands per year. Not only is the turtle used as a national symbol, it is one of the icons of the Caribbean coral reef ecosystem.
It is our collective responsibility to conserve the marine environment and maintain the biodiversity of our planet.