In the French part of the Bay of Biscay, one of Europe’s richest fishing grounds, thousands of dolphins die each year after becoming accidentally entangled in fishing nets.
On average, around a thousand dolphins are found stranded on beaches every winter. But according to the PELAGIS observatory’s analyses reported by Bastien Mérigot, coordinator of the DolphinFree project, the total mortality is estimated to be much higher — with 4,500 to 8,500 dolphins caught in fishing gear every year. Many dolphins that suffocate in nets never make it to the shore — they sink unseen, leaving researchers to grapple with incomplete data on the full extent of the problem.
These losses not only undermine marine ecosystems — they also disrupt the livelihoods of fishers who depend on these waters. For the second winter in a row, authorities have imposed a month-long closure of fisheries to reduce the risks to dolphins. In the meantime, several European research projects are looking for innovative technological solutions that can protect marine life without halting fishing altogether.
Technology that speaks to dolphins
To address the Bay of Biscay crisis, the DolphinFree project, funded by the European Union and the fishing sector association “France Filière Pêche”, is pioneering a new approach: an acoustic beacon for fishing nets, designed to integrate with dolphins’ natural sonar-based communication. This device emits signals that mimic the echo patterns dolphins rely on to navigate their surroundings. By creating an acoustic image of danger — a recorded echo of a fishing net with a dead entangled dolphin — the beacon prompts dolphins to avoid the area.
Initial tests conducted by the scientists show promising results. Dolphins react to the beacon’s signal by steering clear of the area in which the sound is emitted. However, for this technology to become officially adopted, it must prove effective in large-scale trials onboard professional fishing vessels.
Fishers suggest the beacon devices need to be scaled down to better fit through fishing gear machinery. The devices must also remain affordable for fishers who operate with nets stretching tens of kilometres long. The beacons also require regular maintenance and recharging, which adds to the workload of already overstretched crews.
The ongoing trials of DolphinFree and another electronic solution shortlisted by the French government will run throughout 2026 on more than 200 fishing vessels, with the aim to refine the technology and ensure it meets the needs of fishers while delivering a target of 30-40% reduction in dolphin deaths — and hopefully preventing future winter fishery closures.
Bycatch and trawl nets: a global issue
Dolphins are not the only victims of unintended capture in fisheries. Globally, an estimated 40% of all fish catches consist of bycatch — marine species captured unintentionally. These include juvenile or protected fish and other species — such as turtles and seabirds. Often, these animals are simply thrown back into the sea, many of them dead or dying, which contributes to vast amounts of waste and unnecessary ecological harm.
Trawl nets, used extensively in commercial fishing, are particularly problematic. These large, moving nets sweep up everything in their path, trapping species indiscriminately. Fishing fleets face growing scrutiny for the environmental impact of their practices, with increasing demand for more selective fishing methods.
An AI-powered trawl net
To tackle the issue of bycatch at its source, the Marine Beacon project, another EU-funded initiative, is developing an AI-powered smart trawl net. It’s based on the “Game of Trawl” concept created at the IFREMER institute in Lorient, France.
Unlike traditional nets, the smart trawl uses underwater cameras and machine-learning algorithms to identify and sort the catch in real-time. The system can distinguish between target species and non-target marine life, triggering an automatic escape route for unwanted catches. According to marine biologist Robin Faillettaz, who leads the work at IFREMER, such “active selectivity” can offer a “paradigm shift” in how fishing operations are conducted.
In lab tests, the smart trawl net has demonstrated its ability to identify fish species on a video recording and control the trap door designed to let the catch out or keep it in the net. The next challenge is adapting this technology for use on large commercial vessels. Engineers must ensure the system is robust enough to withstand harsh ocean conditions, compact and lightweight enough to avoid hampering operations, and user-friendly so that fishers can integrate it seamlessly into their daily routines. The goal is for the equipment to be deployable within minutes and reliable for use in demanding environments.
