Early trials of a new type fishing net showed that porpoises were able to avoid getting entangled in it.
Putting plastic in oceans is rarely good news for marine life, but this solution to the fishing industry’s bycatch problem could help to save thousands of porpoises, dolphins and whales from drowning.
Some 300,000 whale species die after getting tangled in fishing gear – including nets and lobster pot lines – each year. The creatures use echolocation to navigate obstacles, but as many nets are ‘invisible’ to their built-in sonar, they can easily become trapped.
Now marine biologists in Germany have hit on a way to make nets audible to cetaceans’ acoustic signals: by threading them with tiny beads made from acrylic glass.
The polymer echoes biosonar signals and warns animals. Early tests of the low-tech solution in Baltic Sea suggest that porpoises avoided beaded nets.
Daniel Stepputtis is a marine biologist from the Thünen Institute of Baltic Sea FisheriesRostock is combining his creation with an acoustic device which sounds artificial porpoise warning signs, in the hopes of addressing one Possible shortfall: His research showed that some animals were still getting entangled despite beaded nets. He believes they may have been asleep, even though dormant porcupoises swim and mute echolocation.
Stepputtis plans to tune the beads to species’ specific frequencies and says that can be applied in other settings including freshwater rivers.
The acrylic glass beads bounce back biosonar signals to dolphins. Image by D Stepputtis
Similar low-tech initiatives have also produced encouraging results elsewhere. Research published earlier this yearCurrent Biology, an international scientific journal, reported that attaching green lights on fishing nets significantly reduces unintentional marine organisms that get tangled up in them. It also doesn’t affect fish catches.
The lit nets were tested off Baja California, Mexico. They were found to catch 63 percent less bycatch than the unlit nets. This includes 51 percent fewer turtles and 81% fewer squid.
Meanwhile, a 2019 study by the University of ExeterIt was found that lighting on fishing gear reduced turtle bycatch 70% A separate studyWhen nets were lit, seabird bycatch dropped by 85 percent
Main image: NOAA
