Reference: Grimaldo, E., Herrmann, B., Jacques, N., Kubowicz, S., Cerbule, Okay., Su, B., Laren, R., & J. Vollstad. 2020. “The impact of long-term use on the catch effectivity of biodegradable gillnets.” Marine Air pollution Bulletin 161 e111823.
“Ghost fishing” refers to how previous or discarded nets can nonetheless ensnare fish or different marine life whereas floating within the water after they’ve been misplaced or deserted. Within the fishing trade, gillnets are a typical and cheap strategy to catch fish. These lengthy nets grasp down within the water, catching fish by the gills as they attempt to swim by means of the web. Gillnets are efficient and low-cost, however issues can happen if the nets are misplaced or deserted within the ocean. Previous nets can lure sea turtles, dolphins, seals, birds, animals that weren’t the unique fishing goal. This could trigger accidents, forestall animals from having the ability to transfer freely, and even cease mammals from attending to the floor for air. It’s estimated there are about 640,000 tons of ghost nets presently within the ocean.
These nets are fabricated from artificial (man-made) plastic fibers like nylon, that are immune to breaking down so the nets will keep within the water for a very long time. When the nylon fibers do break down, they will create smaller microplastics that additional pollute the ocean.
So easy methods to remedy this downside? Some researchers and citizen scientists are placing effort into monitoring misplaced nets and re-collecting them. The Nationwide Oceanic and Atmospheric Administration’s Marine Particles program is working with fishermen to scale back the quantity of “ghost nets” in coastal waterways, for instance. Another choice, nonetheless, is to transition to nets fabricated from biodegradable (pure) fibers, as a substitute of artificial fibers. These biodegradable nets fully degrade and subsequently don’t “ghost fish” for very lengthy, they usually don’t create microplastics. However are these nets as environment friendly as the standard nylon nets?
Researchers from Norway got down to check this actual query. They deployed 16 biodegradable and 16 nylon gillnets over the course of three Atlantic cod fishing seasons, with every season lasting roughly three months, for a complete of about 1000 hours within the water. In between seasons the nets have been held in storage. The biodegradable nets have been fabricated from a resin known as PBSAT- a kind of pure resin blended with a biodegradable polymer. The researchers in contrast what number of fish have been caught in biodegradable and nylon nets, and the way giant these fish have been. This info was used to find out what’s known as the relative catch effectivity– or how environment friendly every kind of internet is relative to the scale of the fish being caught.
Researchers additionally carried out a separate experiment, simulating the situations the nets would see within the ocean to find out how the power and chemical properties modified over time, and the way the nets broke down or degraded.
Unsurprisingly, the biodegradable nets broke down considerably through the growing older check in comparison with the nylon nets. On condition that that is the purpose of biodegradable fibers, that end result was anticipated. Nonetheless, the biodegradable nets have been additionally much less environment friendly at catching cod than the nylon nets, on common catching 18.35%, 40.20%, and 47.36% fewer fish in every season than the standard nets. The distinction between efficiencies was extra apparent within the 2nd and threerd seasons, displaying that the longer the biodegradable nets have been within the water, the extra they broke down and the much less environment friendly they have been at catching fish.
These outcomes don’t supply a transparent reply to the issue of ghost fishing. Biodegradable nets did break down extra rapidly, however in addition they weren’t fairly as efficient at catching giant fish as the standard nylon nets. In addition they degraded extra rapidly over time than the nylon nets, which implies they aren’t possibility for long run use.
Nonetheless, utilizing these nets for the brief time period may be possibility for sure fisheries. Within the Norwegian cod fishery, for instance, fishermen usually alternate their nets for a brand new one each season, as a result of the price of repairing a internet is greater than the price of shopping for a brand new internet. Biodegradable nets that should be changed each season won’t be a giant change for fisheries like this. This might cut back the “ghost fishing” impact. Nonetheless, these biodegradable nets nonetheless catch on common 10-40% much less fish than standard nylon nets, which may negatively have an effect on how cost-effective fisheries are and affect whether or not or not fishermen settle for this completely different kind of internet.
In conclusion, this analysis exhibits how rapidly biodegradable gillnets break down and lose their effectivity, which is nice for lowering ghost fishing however leaves one thing to be desired when it comes to catch effectivity. Sooner or later, in an effort to transfer in the direction of a plastic-free fishing trade there could need to be administration incentives to advertise using much less environment friendly biodegradable nets. New developments in biodegradable know-how may additionally assist improve the long-term effectiveness of those nets.
Nonetheless, the information isn’t all doom and gloom. There are a variety of organizations and authorities teams with initiatives aiming to scale back the variety of artificial nets misplaced on the planet’s oceans. Under are hyperlinks to some particular initiatives. Whereas it’s arduous to scale back ghost fishing except you your self are a fisherman or fisherwoman utilizing these nets, everybody may help with the overall downside of plastic within the oceans. Each time doable restrict your use and buy of single use plastics. Convey reusable grocery baggage and take-out containers, make an effort to purchase produce that’s not packaged in plastic, and use your voice and vote to advocate for presidency insurance policies that acknowledge the necessity to tackle the ghost fishing downside and cut back our international plastic consumption.
I’m a second 12 months Masters scholar in Oceanography on the College of Connecticut, Avery Level. My present analysis pursuits contain microplastics and their results on marine suspension feeding bivalves, and organic options to the problem of microplastics. Previous to grad college I obtained my B.S in Biology from Gettysburg Faculty, and labored for the united statesGeological Survey earlier than spending two years at a distant salmon hatchery in Alaska. Most of my free time is spent on the gymnasium, fostering cats for a neighborhood rescue, and looking for the most effective chilly brew in southeastern CT.