Trawling for a sustainable future with smarter nets
Commonly used bottom-trawling commercial nets can wreck the sea floor and waste huge amounts of unwanted or undersized fish, caught alongside target species. Now French researchers are pioneering smart, AI nets with cameras, able to identify, sort and separate a catch before it’s landed
Produced by Alpha Grid
You can enable subtitles (captions) in the video player
Life in our oceans is under threat from overfishing and the environmental damage caused by commercial fleets. With one of the biggest fisheries in Europe, France takes a hefty 900,000 tonnes every year, with at least 65 per cent of that catch coming from the sea. The French Research Institute for the Exploitation of the Sea, or Ifremer, is developing new ways to fish sustainably.
We need to ensure that the fishing doesn't impact too much the stocks, but also does an impact too much the environment and the ecosystems around.
I'm diving into the Ifremer test lab at the Port of Lorient and examining some innovative projects, starting with the intriguingly-titled game of trawls. The most common type of commercial fishing in France, bottom trawling, drags weighted nets over the ocean floor. Indiscriminate and wasteful, that leaves up to half the catch unwanted or undersized and thrown away. Game of trawls aims to make the process smarter and more selective.
This one is really about using video, real-time video and artificial intelligence.
A stereoscopic camera linked to a microcomputer classified species in the blink of an eye.
The computer is detecting some fish and then is able to classify them. Like, in pink we can see the sardine. And in blue, the horse mackerel.
Here, unwanted horse mackerel, or scad, are identified and isolated amid a prime catch of sardine. Illuminated by LED lamps against a white background. The scad and any other undesirable undersized fish can be released automatically into an escape chamber. Lined with a wider mesh, it allows them to swim free. Undersea tests like these show smarter nets can trap the targeted fish, while allowing the others out.
If you didn't want one of these species of fish, or there were too many of the unwanted species, that's when you would open the trap, which can either be operated manually or automatically.
The entire system, designed to withstand extreme pressure at depths of up to 300 metres, is on its way to ocean testing, along with other promising designs. Experiments with fluorescent-coloured material and different kinds of lights have shown that nets can be made to attract or repel different kinds of fish. That could be a simple way to save unwanted species from getting caught in the first place.
Other sustainability experiments have been successfully tried at sea. Research scientist Benoit Vincent is showing me the test tank used to develop more efficient nets and hydrodynamic-weighted shoes fixed at the mouth of the net. The latest designs minimise contact with the seafloor, reducing environmental damage and drag, which saves fuel and cuts costs.
When we went aboard the fishing vessels and found it quite efficient, we could measure that an average savings of fuel is about 10 per cent.
Researchers are keenly aware that making sustainable fishing more viable and profitable is crucial to having such a system successfully fitted and used by trawlers and other fishing boats.
Here's a new take on a well-worn method that's been around for millennia, the drop pod.
The idea is to design a trap that would be able to catch commercially-valuable fish.
Traditionally used to capture crustaceans, the humble lobster pod is being redesigned to bring up premium species like black seabream. Ifremer's fish pod is suspended just above the seafloor so there's little, if any environmental impact there. Adjusted and baited to attract specific targets, it's a gentle and potentially profitable way to fish.
Because it's a static gear, the fish is attracted, enter the trap on its own so there is no stress. So this gear provide the fish with very high quality.
The new design is big enough to bring in a viable catch, yet collapsible and therefore small enough to stack on a boat.
Oh, that's smart.
Smarter still, the pods are foldable and flexible, yet strong enough to withstand collapse in the notoriously strong currents of the Brittany Coast. Like his father before him, long-time local fishermen and fleet manager Eric Guicgnac knows these waters intimately. Eric welcomes scientists on board his vessels. Testing equipment like the Ifremer net cameras he hopes will soon be able to sort his catch on the sea floor.
Eric tells me he's also experimenting with nets that emit sonic pings to deter dolphins and other mammals.
Commercial fishermen have not always seen eye-to-eye with governments and agencies working to manage stocks and regulate the industry. But with the marine environment under pressure like never before, cooperation is key to sustaining a viable future for the fish and for the fishing industry.