Scientists extract DNA from Hawksbill Turtle products to help save species

Scientists have developed a test to extract DNA from hawksbill turtle products, including tortoiseshell jewelry.
Scientists have developed a test to extract DNA from hawksbill turtle products, including tortoiseshell jewelry.

Scientists have developed a test to extract DNA from hawksbill turtle products, including tortoiseshell jewelry.

The novel method could be a major tool to track small and large-scale operations still targeting hawksbills for the illegal trade. 

It’s a breakthrough that could help save the species, hunted for their beautiful shells, and now listed as critically endangered on the International Union for the Conservation of Nature (IUCN) Red List.

A study this year found humans harvested 9 million hawksbill turtles over the past 150 years, more than six times previous estimates.

 A 2008 IUCN assessment estimated there may be only 6,760 breeding females left in the Indian and Pacific Oceans. The number is likely to now be significantly lower.

The DNA extraction project involved WWF-Australia in a collaboration with scientists at the NOAA Fisheries’ Southwest Fisheries Science Center (SWFSC) in California.

Hawksbill turtles from different regions are genetically distinct. If authorities can test seizures of illegal tortoiseshell products, they can pinpoint, which populations are being targeted by poachers and direct policing efforts to those areas.

In developing the test, WWF research consultant Michael Jensen and NOAA scientists faced obstacles.

Shell often contains degraded DNA compared to fresh tissue. The heat and chemical treatments used to create tortoiseshell products could further damage DNA.

 But the team was able to modify a commercially available DNA extraction kit to effectively work on hawksbill shell products.

Dr Jensen said: “It was a relief to confirm that we could get high-quality sequences from the shell products. By adapting an available kit that uses standard lab equipment, we’ve created a practical solution.

“Soon others will be able to easily repeat our proven method and extract DNA from tortoiseshell jewelry, whole shell or pieces of shell.”

Thirteen tortoiseshell jewelry items sourced from local markets in Papua New Guinea (PNG) and the Solomon Islands were tested in NOAA’s genetic lab in La Jolla, California.

“We extracted and sequenced mitochondrial (mt)DNA, inherited from mothers. When females lay eggs they always return to the beach where they hatched, so their DNA tells us their nesting origin,” Dr Jensen added. 

DNA was successfully extracted from 12 of the 13 items. Of those 12, eight were associated with either PNG or the Solomons.

The other four had no known nesting origin. This is because most hawksbill populations in the Asia-Pacific region have not yet had their DNA signatures characterised. 

The next step in the project is to build a more comprehensive genetic database of all hawksbill rookeries.

Some genetic information has been published by scientists and other organisations over the years, but there are many gaps to fill.

The DNA test and subsequent database will not only fight the illegal trade. Combined with tagging and satellite tracking, DNA will help identify all hawksbill populations, how they are connected, where they go, and which rookeries are most at risk from poaching. 

WWF-Australia is working with local scientists and communities to develop ShellBank – a baseline data set being established across Asia-Pacific for hawksbill rookeries.

Building a comprehensive genetic database has been a long-standing goal for NOAA scientists in order to accurately carry out population assessments and evaluate threats for these migratory species. 

“This work is only possible through extensive partnerships with scientists, government, non-profit organisations and village communities living at the remote nesting sites around the Pacific,” said Peter Dutton, who has led NOAA’s Marine Turtle Genetics Programme for over two decades. 

“Having a reference collection of DNA and standardised analytical tools will allow us to build databases that serve as baselines to assess the impacts of additional threats, such as fisheries by catch,” Dr Dutton said.

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