Both turtles were fitted with a satellite-transmitter while laying their eggs on the beach.

Satellite-transmitters allow scientists to track the movements of turtles once they have returned to sea. Little is known about the exact routes turtles use for migration and researchers are also interested in the potential interactions with human activities - in particular fishing - and environmental changes.

The harnesses will be removed when the turtles return to the same beach after two years. However, parts of the harness are designed to disintegrate in time, and release the turtle should the opportunity for removal not arise. The equipment does not harm the turtles.

Sky TV will be airing a documentary about the turtle tagging as part of their series 'Final Chance to Save' on 18 September (8pm, Sky One).

Rob McNeil, Senior Press Officer for WWF-UK helped to tag the turtles. Read his diary to find out what happened.

Leatherbacks and WWF

Leatherback turtles are classed as Critically Endangered by the IUCN. Their greatest threat comes from entanglement in fishing nets and lines.

WWF is working to conserve leatherback turtles by:

• protecting nesting beaches and nearshore habitats by establishing and strengthening sanctuaries and wildlife refuges;
• raising awareness so that local communities will protect turtles and their nests;
• promoting regional agreements to conserve marine turtles;
• reducing longline fishing bycatch through promoting and facilitating fishing gear modification, using new migration and genetics information to develop and trial management measures and,ensuring that any traditional take is sustainable.

Why is this species important?
Jellyfish are a favourite prey of leatherbacks. They keep the jellyfish population under control which is vital as an overabundance of jellyfish can lead to decreased fish populations (including commercially important species) as the jellyfish prey on fish larvae.

Leatherback facts
The biggest ever recorded leatherback turtle was a male stranded on a Welsh beach that reached 256cm long and weighed 916kg.

A leatherback was recorded to have descended to a depth of 1,230 metres - the deepest dive ever recorded for a reptile.