Beneath the Surface: Meet the turtles that call Port Stephens home

The most common species of turtles regularly encountered in the waters of the Port Stephens-Great Lakes Marine Park are the Green turtle and the Loggerhead turtle and occasionally the Hawksbill turtle can be seen.

Two other turtles have been recorded in the offshore waters of the marine park; Flatback and Leatherback turtles however their occurrence is rare.

Turtles are better known from the warm tropical waters of the Great Barrier Reef, however in a scene straight out of Finding Nemo they have travelled down on the East Australian Current and taken up residence in Port Stephens where they appear to live for long periods.

The Green Turtle can be found feeding on seagrasses throughout the Port; snorkelling and diving around Fly Point in Nelson Bay provides a good chance of encountering one.

The Green Turtle is the most typical sea turtle, possessing a teardrop-shaped carapace and a pair of large, paddle-like flippers.

Despite the turtle's common name, it is lightly-coloured all around while its carapace's hues range from olive-brown to black.

The turtle is actually named for the greenish coloration of its fat and flesh.

The Loggerhead is a large turtle which a much bigger head and is so called because of its large head and thick muscular jaws, which it uses to crush food such as crustaceans, molluscs and jellyfish.

Unfortunately plastic bags look like jellyfish and loggerheads often die from ingesting plastic bags washed into our waterways so it's important that any plastic bags are disposed of correctly.

Most loggerheads grow to about 1 m long and can weigh up to 150 kg.

The Green and Hawksbill turtles look very similar to each other however they have some differences in appearance.

The Hawksbill can be distinguished from the Green turtle by its sharp, curving beak with prominent cutting edge, and the saw-like appearance of its shell margins.

Sponges are the principal diet of hawksbills once they enter shallow coastal waters and begin feeding on the bottom.

Hawksbills are also known to feed on other invertebrates, such as comb jellies and jellyfish.

All marine turtles are protected in Australia.

The main threats are pollution and changes to important turtle habitats, such as coral reefs, seagrass beds, mangrove forests and nesting beaches.

The major threats to turtles in Port Stephens are accidental drowning in fishing gear, especially crab traps, and injury caused by boat strike.

NSW DPI rule changes in 2016 to the design of crab traps used in Port Stephens has greatly reduced the risk of turtle entanglement and subsequent drownings.

Care needs to be taken when driving boats around the Port to watch out for the turtles as a boat strike can cause serious injury to a turtle and may result in death.

Don't forget that you visiting a marine park so the taking and harming of marine life is prohibited so please ensure you respect and look after the marine environment.

For further information on the marine park visit dpi.nsw.gov.au/fishing/marine-protected-areas/marine-parks/port-stephens-marine-park.

Dr David Harasti is a senior marine scientist with the NSW Department of Primary Industries Fisheries, based at Taylors Beach.

To showcase the Port's incredible underwater world the Examiner has collaborated with regular Nelson Bay divers and photographers on a series that explores life Beneath the Surface.