A new study published recently in Science Advances shows that sea turtle numbers are increasing worldwide. The authors of this paper examined trends in annual sea turtle nesting numbers across the world and found that of the 299 datasets studied, 95 showed increases in abundances while 35 showed decreases. This is the first time such a comprehensive study was done on the global scale and for all seven species of sea turtles.
This is very encouraging news for sea turtle conservation and is testimony to effective practices put in place as far back as the 1950s. It shows that simple strategies like protecting turtles’ habitats, protecting nesting females and their eggs, and reducing turtle by-catch have positive effects in the long-term.
The study also showed that small populations of sea turtles have the ability to bounce back and grow. In ecology, smaller populations often have a higher risk of disappearing – a phenomenon called the Allee effect – but this does not seem to be the case with sea turtles. “The ability for small populations to bounce back, such as the green turtle population in Frigate Shoals, Hawaii, might be due to the fact that males and females aggregate at specific breeding areas, allowing encounters,” comments Dr Gail Schofield, a lead author of the new paper. “Plus, both males and females mate with multiple individuals, which probably reduces the risk of genetic bottlenecks. Immigration from nearby sites, particularly males frequenting more than one breeding ground, might also enhance genetic flow, allowing population recovery.” From a conservation perspective, this means that protecting even the smaller populations of sea turtles is well worth the efforts and is beneficial to the species as a whole.
Even though this study shows that the overall trend is positive, it is key to continue conservation efforts. Some populations of sea turtles are declining. For example there is a high risk that leatherback sea turtles, the biggest of sea turtles, will disappear in the Pacific. On top of that, sea turtles are faced with relatively new threats including climate change and plastic pollution in the oceans.
“The key message of this paper is cautionary optimism,” underlines Dr Schofield. “Our findings demonstrate the success of ongoing efforts, and that these efforts are effective, but that we need to continue funding and support monitoring to safeguard future sea turtle populations.”
“Global sea turtle conservation successes” was published by Science Advances (2017). Authors: Antonios D. Mazaris, Gail Schofield, Chrysoula Gkazinou, Vasiliki Almpanidou and Graeme C. Hays.