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🐬 Effective and low-tech solution to bycatch

🐬 Effective and low-tech solution to bycatch

Fishing nets are usually invisible to animals using echolocation but now marine biologists from Germany have come up with a solution to make nets visible to acoustic signals, helping animals to dodge the nets.

Linn Winge
Linn Winge

Sadly, many non-targeted species, such as dolphins and marine turtles, get caught in fishing nets and it’s a common and massive problem in the industry. This is because many of these animals use echolocation to β€œsee” and most nets are invisible to their sonar. According to Positive News it is very common for whales to die after getting tangled in fishing gear.

Now, marine biologists in Germany have come up with a way to make nets and other fishing gear visible to these animals. They are actually threading them with tiny beads made from acrylic glass. Why? Because these beads can bounce back bio-sonar signals as echos. These signals can easily be picked up by marine animals using echolocation as their vision. The early tests in the baltic sea have shown that porpoises were better at avoiding beaded nets.

However, Daniel Stepputtis, a marine biologist from the ThΓΌnen Institute of Baltic Sea Fisheries in Rostock, discovered one flaw with the solution. Some of the animals that still got entangled in the nets with beads were sleeping. Porpoises can swim while they sleep and they mute their echolocation while doing so. Positive News writes that Stepputtis is pairing his creation of beaded nets with an acoustic device. Its sound is artificial porpoise warning signals. This is an attempt to fix the shortcoming of the nets and he plans to tune the beads to species’ specific frequencies.

Other solutions to the bycatch problems include attaching green lights to fishing nets and it proved to significantly lower the amount of unintentional marine life caught, while still not impacting fish catches.

Positive News write β€œThe lit nets were trialed off the coast of Baja California in Mexico, where they were found to bring in 63% less bycatch than unlit nets; including 51 per cent fewer turtles and 81% fewer squid. Meanwhile, a 2019 study by the University of Exeter found that lights on fishing gear reduced turtle bycatch by 70%. A separate study noted an 85% reduction in seabird bycatch when nets were lit.”

Photo: D Stepputtis via Positive News