Mediterranean turtles recover at different rates
The number of two Mediterranean turtle species has increased over the past three decades – but in Cyprus recoveries are occurring at different rates, new research shows.
The number of nests on 28 beaches shows that green turtle nests increased 162% from 1993 to 2019, while loggerhead nests increased by 46%.
The research team – from the University of Exeter, the Society for the Protection of Turtles (SPOT) and the University of the Eastern Mediterranean – say the difference is likely due to higher death rates among loggerhead turtles of all ages.
Turtles in this region used to be hunted for meat and shellfish, but this is now banned throughout the Mediterranean. Coupled with the conservation of nesting beaches, this has allowed populations to recover – but scientists say better protection at sea is still needed.
âThe recovery of these populations is very encouraging,â said Dr Lucy Omeyer, of the Center for Ecology and Conservation at the Penryn Campus of Exeter in Cornwall.
âHowever, the different recovery rates suggest that loggerheads face additional threats than those faced by green turtles.
“The seagrass diet of adult green turtles might partly explain this, as it means that green turtles are less likely to be accidentally caught (accidental capture by fishermen), because for most of their lives they are live in very specific habitats which are also protected. .
âGreen turtles are also more likely than loggerheads to return to the same nesting beaches and stay close to the beach, while loggerheads move to fishing grounds during nesting season.
The study found “stable” reproduction rates in loggerheads, suggesting that the death of turtles of all ages (rather than the lack of hatchlings) “hampers the recovery of this species.”
Dr Damla Beton, SPOT, said: âOur other studies have revealed that many mature loggerheads die in fisheries when they visit Cyprus to breed, as well as in the region’s foraging areas.
âIt is therefore not surprising that this mortality is reflected in the nesting trends.
“A better understanding of their movements and the fishing threats they face could help inform conservation measures such as marine protected areas.”
Despite the recovery of green turtles, their total population in the Mediterranean is estimated at only 3,400 adults, while their main breeding and foraging areas are limited to a handful of sites.
The study was supported by the Department of Environmental Protection of Northern Cyprus.
The paper, published in the journal Animal conservation, is titled: “A Study of the Differences in the Population Recovery Rates of Two Sympatry-nesting Sea Turtle Species”.
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