New lab-on-a-chip helps shark conservation

An innovative new paper lab-on-a-chip device can help monitor the number of vulnerable sharks being fished and mis-sold. 

Vulnerable or endangered shark species are caught in large numbers by fisheries and traded around the world, but monitoring is difficult, as current techniques for identifying species rely on visual examination by experts or DNA barcoding techniques, which require specialist laboratory facilities and trained personnel. 

These barriers to identification mean vulnerable species are under threat, and also poses a potential risk to human health, as shark meat can contain high concentrations of pollutants such as mercury which can be harmful when eaten by humans. 

Now researchers from Manchester Metropolitan have developed a paper-based lab-on-a-chip, allowing officials to test fish quickly, easily and cheaply, as detailed in an article published in PLOS ONE. 

The study took place in Ecuador, and focused on identifying three threatened shark species (bigeye thresher, pelagic thresher and shortfin mako shark) at market source.  

Dr Kirsty Shaw, Senior Lecturer in Forensic Biology at Manchester Metropolitan and corresponding author on the study, said: “Sharks are vulnerable to fishing, with many species under threat, but it can be expensive, time-consuming and difficult for authorities to regulate, and often requires personnel with a scientific background.  

“In this project, we have a proof-of-concept that a simple and cost-effective paper lab-on-a-chip can help to monitor which species are being caught and mislabelled as fish, without great expense or the need for scientific training. 

“The aim is to understand the scale of the issue to start, then to try to reduce it by working with fishing industries. 

“We worked with the Ministry for Aquaculture and Fisheries in Ecuador and the feedback was very positive, and they would like to see this expanded to other species as a next step.” 

The study was funded by National Geographic and Save Our Seas Foundation.  

Lead author and Manchester Metropolitan PhD student Guuske Tiktak said: “We successfully extracted DNA from shark meat and fin samples and the results were available in less than an hour, with a ‘yes’ or ‘no’ result indicated by a colour change from pink to yellow when one of the target species was detected. 

“This is an important step in terms of shark conservation but also human health. Shark meat has been found to be mislabelled as other fish all over the world, from fish and chip shops on the south coast of England to further afield, and can be harmful when consumed by humans, due to the levels of pollutants it contains. 

“Improving testing is a win-win for both humans and sharks, and could help to prevent the loss of these vulnerable species over time.” 

The study was led by Guuske Tiktak and Dr Kirsty Shaw, with co-authors from Universidad San Francisco de Quito, the Ministry for Agriculture and Fisheries, Ecuador, Instituto Nacional de Biodiversidad, Ecuador, the University of Delaware and the University of Plymouth.