Researchers from Arizona State University (ASU) had been expecting to find that exploitation of sea turtles around the world had increased over the past decade – so they were pleasantly surprised when their new global assessment identified a 28% decline, with those turtles still being killed or trafficked now more likely to come from less-threatened populations.
“The decline over the past decade could be due to increased protective legislation and enhanced conservation efforts, coupled with an increase in awareness of the problem or changing local norms and traditions,” said the study's co-lead author Kayla Burgher, a doctoral student in ASU’s School of Life Sciences.
Patterns and trends revealed in the study, published recently in Global Change Biology, were based on a review of data from peer-reviewed journal articles, archived media and NGO reports and online questionnaires.
While the reduction was welcomed, it was from a high baseline. More than 1.1 million turtles, 95% of them green and hawksbills, had fallen victim to poachers between 1990 and 2020, the survey revealed.
Despite the legislation designed to protect turtles, up to 44,000 were still being exploited annually over the past decade in 65 countries or territories, and in 44 of the world’s 58 major sea turtle populations.
South-east Asia and Madagascar emerged as the major hotspots for illegal takes and trading, particularly of hawksbills (Eretmochelys imbricata), with their prized shells. Vietnam was the most common country of origin for illegal trafficking, with almost all trafficked products bound for China and Japan. Across all three decades Vietnam-China remained the most common turtle trade route.
Turtles are highly valued sightings for scuba divers and snorkellers, but on the IUCN Red List hawksbills are listed as Critically Endangered and greens (Chelonia mydas) Endangered.
The black-market wildlife trade is considered one of the world's most lucrative illicit industries. ASU assistant research professor Jesse Senko, Burgher's co-lead author, said that while assessing illegal exploitation of turtles was difficult, especially when linked to organised crime syndicates, most such activity reported over the past decade had occurred in large, stable and genetically diverse populations.
“What this means is that most of these sea turtles came from healthy, low-risk populations, which suggests that, with a few exceptions, current levels of illegal exploitation are likely not having a major detrimental impact on most major sea turtle populations throughout the world’s oceans,” said Senko.
But he called for increased support for governments of nations that lacked the resources to protect turtles, and support for communities adversely affected by restrictions or bans. “We must develop conservation strategies that benefit both people and turtles,” he said..
The study did not include theft of turtle eggs, or products such as ornaments made from shells not easily attributed to individual turtles, but Burgher described it as an important foundation for future research and outreach efforts.
“We believe this study can help conservation practitioners and legislators prioritise conservation efforts and allocate their resources to best help protect sea turtle populations from harmful levels of exploitation worldwide,” she said.
Earlier this year, a report led by the UK’s Exeter University found that Seychelles green turtles, once almost hunted to extinction, are now thriving again.
Aldabra, one of the world’s largest atolls, had since the 19th century seen some 12,000 turtles a year hunted for their meat. Following a UK Royal Society recommendation it became a nature reserve with complete turtle protection in 1968, and 14 years later was also designated a UNESCO World Heritage site.
The effect is described as “astounding” in the study published in Endangered Species Research. The scientists found that Aldabra now had the second-largest green turtle breeding population in the western Indian Ocean region, with 3,000-5,000 females nesting each year – and they thought it possible that the current population could double again.
Similar recoveries in green turtle populations brought about by protecting nesting areas have also been recorded in Australia, Costa Rica, Hawaii, Mexico and on Ascension Island.