An underwater robotic sorting device which helps fishing trawlers prevent bycatch by identifying and sizing fish and other marine life in real-time is being developed by researchers from Heriot-Watt University in partnership with Fisheries Innovation & Sustainability (FIS) and funded by the UK Seafood Innovation Fund.

Smartrawl uses AI-technology to determine the individual size and species of marine life captured inside a trawl net using images taken by an underwater stereo camera. It then releases or retains each marine animal depending on whether it qualifies against a trawler’s intended catch using a computer-controlled robotic gate.

Trawling is a fishing practice that herds and captures target species, like fish or prawns, by towing a net along the ocean floor. This method of fishing is known to cause discarding and bycatch, where fish or other marine animals are accidentally caught and returned to the sea, most often dead. According to global marine fisheries data, it is estimated that 46% of all marine fish that are discarded come from this method of fishing.

Smartrawl has been developed to ensure that vessels only catch the fish they’re targeting, releasing other animals back into their natural environment quickly and without harm.

Developed by researchers from the Lyell Centre and the National Robotarium at Heriot-Watt University, the sorting device has been designed in collaboration with the UK fishing industry. It is able to fit into existing nets of all sizes of vessels and requires no additional cables due to the device’s patented gate system which works with the force of the water to rotate between open and closed states.

Paul Fernandes, the inventor of Smartrawl, is scientific lead for the project. He is a professor of fisheries science and technology at the Lyell Centre and Heriot-Watt Bicentennial Research Leader. He said: “More than 4 million tonnes of marine fish are unintentionally caught by trawlers around the world every year, as well as bycatch of sharks, rays, dolphins, critically endangered turtles and seabirds. The sad reality is that these creatures, more often than not, are returned to the sea dead or dying.

“Current methods used on trawlers are unable to distinguish between different species and animals or give skippers enough information to build an accurate understanding of the size of individual fish prior to capture.

“Smartrawl has been developed to ensure that vessels only catch the fish they’re targeting, releasing other animals back into their natural environment quickly and without harm. As a result, we’re confident that discarding and bycatch could quickly become a thing of the past and our precious marine life preserved.”

Further information on Smartrawl can be read here.