The fiftieth anniversary of the Bermuda Turtle Project is to be celebrated by the Bermuda Post Office with a commemorative stamp issue on Thursday.

Four marine turtle stamps will be issued, featuring green turtles, as well as the hawksbill, loggerhead and leatherback, which the project has been studying and tracking since 1968.

Turtles constituted an important food source for early settlers, but despite legislation from as early as 1620 to protect them, nesting populations were wiped out.

Green turtles are the most common and nesting has returned with a few isolated events in recent decades.

The project’s mark and recapture study has analysed information from about 4,000 green turtles and 138 hawksbill turtles living in Bermuda’s inshore waters between 1968 and 2016.

More than 1,500 recaptures of tagged green turtles has provided one of the largest sources of information in the world on growth rates, habitat use and movements of free-ranging young green turtles.

Five species of marine turtle are found in Bermuda.

Hawksbills are often seen, usually on coral reefs.

Loggerheads and leatherbacks are sometimes spotted in deeper waters, while Kemp’s ridley is only rarely seen.