Accidental discovery that scallops like ‘disco’ lights leads to new fishing technique | Environment
An unusual technique for catching scallops, discovered by chance by scientists, could potentially reduce some of the damage done to our seabed by fishing.
Marine scientist Dr Rob Enever and his team at Fishtek Marine, a Devon-based fisheries consultancy, have designed small underwater ‘potlights’ to help protect fish stocks by replacing the need to use fish to bait crab and lobster pots.
The lights were supposed to attract the crabs to the pots. But quite unexpectedly, the scallops, which can have up to 200 eyes, were more attracted to the LED lights. “It’s like a scallop disco – turn on the trap and they come in. It’s amazing that no one else has discovered this before. It’s quite an exciting discovery,” Enever said.
“It has the potential to open up a whole new inshore fishery and it’s a world first.”
Commercially, scallops are England’s most valuable fishery and the fourth most valuable in the UK, according to the latest government sea fishing statistics. Most are fished out by dredging which, on an industrial scale, damages marine habitats. However, hiring divers to handpick them is labor intensive, time consuming and therefore more expensive.
Enever hopes that stuffing scallops could create a low-input, low-impact fishery that would supplement crab and lobster fishermen’s incomes with these high-value catches.
In 2019, Enever, which specializes in reducing the impacts of fishing on the marine environment using technology, tested the lights with Newlyn-based fisherman Jon Ashworth off the Cornish coast. . Although Ashworth noticed no difference in crab or lobster catches, he found large numbers of European king scallops in his traps.
“Almost every trap we hauled had scallops in it and yet every tow without lights had no scallops. It was conclusive, on the spot,” Ashworth said. “Having proof that lights can be used to catch scallops must have impressive implications for the future.”
In other experiments, a total of 1,886 traps were carried – 985 experimental traps with lights caught 518 scallops; 901 control jars without lights took only two. Overall, 99.6% of scallops were caught in lighted traps. This research, funded by Defra and Natural England, is described in a peer-reviewed article published this week in the Journal of Fisheries Research.
Dr Bryce Stewart, a marine ecologist and fisheries biologist at the University of York, has studied scallops for over 20 years and co-authored the paper with Evener alongside scientists from the University of Exeter.
“It’s one of the most exciting things I’ve come across in my entire career — it’s such a surprise,” said Stewart, who describes the scalloped eyes as “pretty weird.” Scallops can have up to 200 eyes on their mantle, along the inner edges of their shell openings.
“Most animals, including us, have lentils, but scallops don’t. They have mirrors in the back of their eyes and they also have two retinas, one that detects darker things, one that detects lighter things, so they can possibly use that contrast to detect motion. Perhaps they prefer lighted areas because it protects them from predators or because it is easier to find the plankton they eat.
Powered by two rechargeable AA batteries, each small recessed light is secured inside the pot and should last between five and 10 years. The trap design has been modified with a ramp for easier access to the modified pot and Enever continues to refine potlight technology – tank experiments indicate that scallops are more attracted to blue light than white light, per example. If the team can design a lighting system aimed specifically at catching scallops, it could open up the possibility of doing so on a large scale, according to Stewart.
“Scallops are famous for their good vision,” said Dr Vicky Sleight, a marine biologist at the University of Aberdeen. “The eyes of scallops have a surprisingly high degree of visual clarity and their attraction to artificial light is intriguing. Follow-up laboratory experiments are needed to understand why they are attracted to traps, and if this is reliable and repeatable behavior across a range of different types of scallop sites, then it is certainly a prospect. exciting to develop a more sustainable scallop fishery.
The Fishtek team are repeating these experiments in four other locations in the UK, from Lyme Bay to the Orkney Islands, using different trap designs in varying conditions and depths.
“Our goal is to get as close as possible to a commercially viable fishery,” Enever added. “I honestly think we can do it, there’s mileage.”