Female turtles that lay eggs at key rookeries in Cyprus prefer to forage in Lake Bardawil in Egypt, according to researchers. Lake Bardawil, located on the Sinai Peninsula’s northern coast, is a large, shallow lagoon with an artificial opening that connects to the sea. It began as a fishery in the 1950s and has since evolved into an ideal seagrass habitat for adult green turtles.
The number of green turtles breeding in Cyprus has increased in recent years, but this rebound is heavily dependent on an Egyptian lagoon where many turtles feed, according to new research. Green turtles, an endangered species, spend the majority of their lives foraging in one area, but they return to the beach where they were born to lay eggs.
The new study, by the University of Exeter and the North Cyprus Society for the Protection of Turtles (SPOT), tagged and tracked females laying eggs at key rookeries (breeding beaches) in Cyprus, and found 74% forage at Lake Bardawil in Egypt.
Since about 2010, our tracking of turtles from Cyprus has shown a large increase in the number foraging at Lake Bardawil. At the same time, the number of adult turtles foraging around Cyprus and Turkey has decreased, possibly due to high bycatch (accidental catch) of turtles in local fisheries.
Dr. Robin Snape
The study found that nest numbers have almost tripled since the early 1990s – but the dependence on a few feeding sites, especially Lake Bardawil, leaves turtle populations vulnerable if conditions there change.
“Since about 2010, our tracking of turtles from Cyprus has shown a large increase in the number foraging at Lake Bardawil,” said Dr. Robin Snape of Exeter’s Penryn Campus in Cornwall.
“At the same time, the number of adult turtles foraging around Cyprus and Turkey has decreased, possibly due to high bycatch (accidental catch) of turtles in local fisheries. The overall increase in nest numbers appears to be driven by the protection of nesting sites in Cyprus and the conditions at Lake Bardawil. It is possible that the lake will reach capacity, at which point the green turtle population will cease to grow.”
Lake Bardawil is a lagoon with a human-made opening that connects to the sea, allowing marine life including turtles to swim in and out. It was created in the 1950s as a fishery, but it has become an ideal seagrass habitat for adult green turtles, which are typically over a metre in length and weigh more than 100kg. The new study used long-term satellite tagging to track 19 female turtles nesting at major rookeries on the Karpaz Peninsula, Cyprus.
While most of the turtles went to Lake Bardawil, one migrated 1,500 miles (2,400km) to Djerba island, Tunisia – the longest distance yet recorded for a Mediterranean green turtle. Comparing the oldest available three-year nest count averages (1993-1995) with nest counts undertaken as part of this study (2017-2019), average annual nest numbers increased from 186 to 554.
“Given Lake Bardawil’s importance for green turtles in the Eastern Mediterranean, it’s critical that the habitat there is managed in a way that protects turtles while also supporting fishers’ livelihoods,” said University of Exeter Professor Annette Broderick. Reducing bycatch and protecting habitats in other areas could boost green turtle populations and reduce reliance on this single location.”
The MAVA Foundation and the Natural Environment Research Council provided funding for the study. The paper is titled “Mediterranean green turtle population recovery increasingly depends on Lake Bardawil, Egypt,” and it was published in the journal Global Ecology and Conservation.
