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Bright Idea: Lit Fishing Gillnets Reduce Bycatch

When discussing sustainability, most people think of stereotypical images of pollution — giant smokestacks seeping from the tops of factories. Others might think of massive landfills overflowing with waste. Few, however, consider the enormous trash from our food production pipelines, whether it’s sitting in a dumpster behind a local fast food chain or the invisible methane clouds from livestock farms. Of that small group of people, even fewer will stop to question the fishing industry’s impact. 

One issue at the forefront of waste conversations in commercial fishing operations is “bycatch.” It’s the industry’s catch-all term for the many marine life species caught unintentionally along with the desired quantities of commercial fish. It’s a situation that has traditionally been deemed unavoidable, given the nature of large-scale fishing ships. To catch their desired fish type — whether cod, tuna, salmon, lobster, or any of the dozens of aquatic creatures consumed in the U.S. — these ships cast large sheets of netting called gillnets into the water. Gillnets entrap whatever falls inside of them. So, just like that famous Finding Nemo scene, other species like stingrays and sharks in the vicinity of these commercial targets are often swept up to the ship’s deck. 

Photo Courtesy NOAA

In 2022, marine and industry researchers are asking themselves: what if we just put lights on the nets? The idea has been floating around for years; however, it was only recently that well-funded studies were able to put this question to the test. In theory, while illuminated gillnets would succeed in warding off unwanted species from entering the area, scientists feared they could potentially reduce the number of desired fish caught. The coronavirus pandemic has already proven significant vulnerabilities in our domestic food supply chain, so reducing commercial fish would have disastrous effects on the public. 

Led by researchers at Arizona State University, the experiment results proved to be a smashing success.

The catch rates and overall market value of caught fish are virtually identical to typical situations, and the reductions in bycatch were impressive. The total bycatch amount decreased by 63%, with a whopping 95% reduction in sharks, skates, and rays caught.

Other notable declines included 81% less Humboldt squid and a 48% decrease in unwanted finfish. 

Photo Courtesy NOAA

These results raise the question of whether lighted gillnets should become the industry standard. While regulatory changes requiring these nets may eventually come, it is critical first to consider whether fishermen would adjust voluntarily. Although the lights aren’t free at roughly $140 per net, proponents argue the 57% reduction in time spent untangling bycatch compared to non-illuminated nets would make the investment worth it for large fishing companies. 

“It is important for fishers to know that there are tangible benefits for them,” said John Wang, a scientist at the National Oceanic and Atmospheric Administration (NOAA). “This is critical for the adoption of such technologies by the fishing industry.”


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