Loggerhead turtles are a common turtle seen around the Whitsundays while cruising with Whitsunday Catamarans. While not the most common of all the turtles you may see here, they are a local resident that are often encountered on the reefs. Of all the 6 types of turtles that frequent Whitsunday waters, they are the most endangered of all the species and are carefully protected.
Gentle cruisers that are a site to see, they feed on molluscs, crustaceans, fish, jellyfish, and other small to medium-size marine animals, which they crush with their large and powerful jaws. Their name comes from their large, oversized head, and they weigh on average between 80 and 200 kg (180 and 440 lb). However, there have been documented cases of some turtles weighing in at 450kg (or 1000lbs)! Their size alone makes them a target for bigger predators such as sharks, but they are more often killed by rogue fishing equipment and nets.
As a seafaring animal, they are not often spotted on land and spend most of their lives in the water. However, as with all sea turtles, females will make their way to land to nest on the same beach where they themselves hatched. They nest every 3-4 years and lay up to four clutches a season of about 110 eggs each. Interestingly, the outcome of the gender of each clutch is completely dependent on temperature, with incubation temperatures of around 32 °C becoming females and those sitting at around 28°C becoming males. If the temperature is around 30 °C, there will be an equal mix of male and female offspring.
These beautiful animals have a yellow-orange to reddish brown head and upper body, with a yellow neck and sides. Their underside, also known as their plastron, is a pale yellow colour. Loggerheads can be found pretty much all over the world, ranging from the Atlantic, Pacific, and Indian Oceans as well as the Mediterranean Sea.
Loggerhead turtles undertake long migrations, often using warm oceanic currents for dispersal. When in open waters, loggerhead sea turtles often float on the surface, presumably sleeping. DNA studies have shown that turtles from different nesting regions differ genetically. This finding suggests that females return to the nesting beaches on which they hatched.
Loggerheads feed mostly on the bottom of the ocean on sponges, worms, conch and other snails, clams, squid, octopus, barnacles, horseshoe and other crabs, shrimp and sea urchin. From the open ocean they will catch and eat fish, jellyfish, algae and other aquatic plants. They have also been known to occasionally hatchling sea turtles, including those of their own species. They have the broadest diet of any sea turtle.
Loggerhead turtles reach maturity between 10 and 30 years of age, living up to 50 years old. Courtship and mating occur most commonly when the turtles are making their way to the nesting grounds during their big migration. This takes place several weeks before nesting begins, where as many species mate much closer to the nesting beaches. The male circles the female, bites her neck and shoulders, and mounts her shell from behind. The pair typically floats at the surface during copulation. Mating can occur day or night. Females are inclined to mate several times causing multiple paternity in the fertilised eggs.
Loggerhead turtles currently have a declining population and are still listed as a vulnerable animal. In Australia, their biggest threat comes from both humans and red foxes, which are known to eat full clutches of eggs they find on beaches. Humans cause damage with fishing nets, boats and pollution, which affect populations dramatically. They were once extensively hunted by humans for their meat, but this practice is now outlawed, however it does still happen in certain countries. Plastic pollution that litters our oceans is ingested by loggerheads, which can cause many health problems that often lead to death. We can help loggerhead populations by always disposing of garbage properly and keeping an eye out when boating in areas they are known to frequent. Being mindful of nesting areas and nesting females is also important to their conservation to ensure future generations have a chance to hatch and make their way to adulthood.