Several years ago while diving a small channel in the outer Great Barrier Reef in Australia, I hovered a foot away from a turtle munching on "turtle grass." This opportunity and several others on my three month diving trip through SE Asia, Australia and the South Pacific left me determined to learn underwater videography when I returned to Catalina. I'd always been fascinated by the early Cousteau documentaries and although I worked with them on one, my only filming then was topside.
My chance to film turtles came on my seven week trip to Belize and Honduras with Lindblad Expeditions. As the small eco-cruise ship's marine biologist and underwater videographer, I was able to dive world-class sites like Lighthouse Reef as well as numerous small tropical islands known as Cayes (Keys) on the Meso-American Barrier Reef. This reef is the largest in the western hemisphere and second only to to Australia's in size.
It wasn't long before I had my first encounter with a hawksbill turtle on the spectacular Half Moon Caye wall on Lighthouse Reef. While diving the wall at about 70 feet, I noticed something out of the corner of my eye and turned to see a hawksbill slowly swimming over the 4,-7,000 foot drop-off (hold on to your camera!). I turned and followed it with camera rolling as it leisurely and gracefully swam along, quite a contrast to its awkwardness on land.
Hawksbills are found in warm tropical and occasionally temperate waters world-wide from Africa to Asia to North and Central America. In the States they are known to nest only in Hawaii and Florida. While researching this species, I was surprised at the wide range of reported sizes. Lengths ranged from 16" to over three feet and weights from 30 to 270 pounds. The wide ranges point to the need to use and assess the accuracy of several sources when researching a report. A reliable source from the Caribbean reported they are up to three feet and average specimens weigh up to 36 pounds with the record being nearly 60 pounds. The range in sizes may be due to differences observed in different regions of the world.
This turtle nests on a wide range of beach types unlike some of its relatives which are more picky. It usually returns to the same beach each time. Nesting season may run from late May through October or even December. A single female may only nest every 2-3 years, but can lay up to six clutches each season, spaced out every 2-3 weeks. After courtship and mating, the females crawl out onto the beach, clear an area above the high tide line, dig a pit to lay her eggs in, and then cover it up. The number of eggs depends on the female's size with 140 eggs per clutch reported in Florida with a maximum of 230 reported. The process may take one to three hours and occurs usually at night.
The eggs hatch in about 60 days and usually at night when terrestrial predators are less of a threat. Like some other reptiles, the sex of the hatchlings may be determined in part by the temperature! The young immediately head towards water, attracted by moonlight reflecting off its surface. They may become disoriented by strong lights, so many beach cities have ordinances forbidding such lighting at seashore developments during nesting season.
It is believed that newly hatched hawksbills are pelagic (open water), hiding among drift algae like Sargassum and floating debris. Later they re-enter coral reefs near the coast where they feed largely on sponges, and are apparently fussy eaters selecting only a few preferred species. However they are also known to eat grasses and algae, sea anemones, soft corals and other invertebrates as well as scavenge on dead organisms. Natural predators on the adults include sharks and humans.
One interesting fact I was unaware of during my dives with them is that they are one of only two poisonous sea turtles. The skin is highly toxic due to chelonitoxin and the flesh itself if eaten can cause death according to one source. However other sources report the use of the meat as food. Of course as with most marine life we encounter on the cruises, touching was forbidden and it definitely was not on the ship galley's menu either (although lobster, grouper and yellowtail snapper were not so "lucky").
Like many turtles, the hawksbill is endangered, and is protected in the States under the Endangered Species Act (ESA), and internationally by the International Union for the Conservation of Nature and Natural Resources and the CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora) Treaty. Threats are many including the loss of nesting beaches due to coastal development, tropical reef degradation, pollution, incidental capture in nets by commercial fishermen, entanglement in debris, ingestion of plastics, and egg harvesting.
Hawksbill shells are the sole source of "tortoiseshell" jewelry and ornaments, also known as bekko, which results in poaching and illegal trade. This species was driven close to extinction by these activities. Fortunately modern "tortoiseshell" glasses are usually made of plastic. Thankfully there are still some hawksbills left to enjoy in Belize, which I hope to dive every year with Lindblad so I can escape the cold southern California winters!
© 2004 Dr. Bill Bushing. Watch the "Dive Dry with Dr. Bill" underwater videos on Catalina Cable TV channel 49, 10:00 AM and 5:00 PM weekdays.
Hawksbill turtle approaching and passing me on
Half Moon Caye Wall, Lighthouse Reef, Belize
This document maintained by
Dr. Bill Bushing.
Material © 2004 Star Thrower Educational Multimedia