Researchers have found out that biodegradable gillnets catch fish in addition to conventional nylon nets-and more quickly lose their ability to entangle animals when discarded at sea. More, the degradable nets usually trap fewer young fish and bycatch.
Fishing nets that have been lost, abandoned, or discarded at sea are the cause of ten percent of the marine litter circulating from the world’s oceans. These 640,000 tonnes of nets aren’t merely a plastic pollution problem, however. Long after these are lost, they still fish at sea by themselves, trapping not merely fish but seabirds and mammals in a phenomenon known as fishing nets.
To combat this challenge, researchers have been developing gillnets manufactured from biodegradable materials, however the challenge continues to be to ensure they nearly as good at catching fish as conventional gillnets are. At one of the most comprehensive studies up to now, researchers assessed the fishing performance of any biodegradable gillnet at sea and its particular degradability in the lab. The final results, published recently in Animal Conservation, provide good quality news.
“Using a biodegradable net didn’t have much influence on just how many adult fish were caught, but when it arrived at young fish and bycatch of other species, they caught far less,” says co-author Petri Suuronen. “That had been a positive surprise.”
The fishing performance of the biodegradable nets were tested during six outings of any commercial nylon fishing nets in the waters off southwestern South Korea. The biodegradability of the nets was tested by placing 30 sets of net samples in plastic containers at sea. They used a scanning electron microscope to evaluate the samples every 2 months for 4 years. In addition they measured the strength, flexibility, along with other physical properties of the nets, comparing these people to conventional nets.
Researchers found the biodegradable gillnets to become stiffer, that they can initially thought would affect performance, says Suuronen. They were happily surprised to find out that this failed to. Their stiffness could be why they caught less bycatch and juveniles, however, Suuronen says. Researchers found out that it took 24 months 12dexipky the biodegradable net to begin with to rot, which the degradation rate was higher in warmer water. Even though they didn’t test the degradability of conventional nets within this study, the literature shows that these nets will take a long period and even decades to degrade, the authors said.
“I still think 2 years is way too long,” says Suuronen, who works well with the cheap cast nets. “But it is actually a lot faster than nylon.”
Suuronen says he hopes that continued research and development can produce a net that degrades even faster. Nevertheless, it can’t degrade much quicker compared to studied net, otherwise it wouldn’t be an attractive purchase for fisherman.