The barge, used to treat injured loggerhead turtles, is the first floating rehabilitation centre for the species in the Mediterranean, its organisers say.

Harbouring netted enclosures underwater, it allows the threatened species to receive care in saltwater, its natural habitat.

"It is important that the sea turtles recover in their natural environment," said Hamed Mallat, a marine biologist who heads the UN-funded project.

"We place them in a space that's large enough for them to move and feed more comfortably," he added.

Mallat, a member of the local Kraten Association for Sustainable Development and the International Sea Turtle Society, founded the project last month and said the rehab barge was refashioned from a sunken aquaculture cage.

It can hold up to five sea turtles at a time, each in its own enclosure, and spans 150 square metres (1,610 square feet) at the surface, with netting below to allow the convalescing animals to reach the sea floor.

The loggerhead sea turtle, also known as Caretta caretta, is considered a vulnerable species by the International Union for Conservation of Nature.

Every year, around 10,000 loggerheads are caught by trawlers and in fishing nets in the waters off Tunisia.

- 'Educational value' -

Life Medturtles, an EU-funded sea life conservation project, estimates that more than 70 percent of sea turtle deaths in the Mediterranean are caused by gillnets -- large nets used for mass fishing.

It is often the fishermen themselves who bring the injured turtles to the barge, said Mallat.

The project is also an opportunity to teach younger generations about preserving sea life, he added.

"This is a direct application of the things we study," said 24-year-old Sarah Gharbi, a fisheries and environment student at the National Agronomic Institute of Tunisia (INAT).

"It's also a first interaction with marine species that we usually don't see as part of our study or in our laboratories. It's something new and enriching."

Her teacher, Rimel Ben Messaoud, 42, said the barge's "educational value" was in giving students a first-hand experience with marine life conservation.

Due to rising sea temperatures, overfishing and pollution, a number of marine species have seen their migratory routes and habitats shift over time.

Mallat said the project could help study those patterns, particularly among loggerhead sea turtles, as Besma now bears a tracking device.

"It gives us a significant advantage for scientific monitoring of sea turtles, which is somewhat lacking in scientific research in Tunisia," he said.

Mallat said he also hoped to attract the islands' summer tourists to raise awareness about the vulnerable species.