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Description
Reduce ghost fishing and the introduction of synthetic plastic material into the ocean. The project supplied biodegradable gillnets and trammel nets to the local fishing community and evaluated the effectiveness of this initiative, The project achieved 1,5 ton plastic recycled through all supported schemes/measures (in a total of 7,5 ton of marine litter). PBSAT biodegradable resin has a slow biodegradation process. PBSAT gillnets have good mechanical properties for fishing and showed a 15% higher fishing efficiency in terms of biomass than nylon. The main potential users of PBSAT nets will be fishermen who change gears more frequently.
Summary of project results
The ecological and socio-economic problems caused by abandoned, lost and discarded fishing gear are increasingly of concern. Used primarily by coastal, artisanal, small-scale fisheries worldwide, marine gillnets and trammel nets, which have relatively high ghost fishing potential, account for about one-fifth of global marine fisheries landings. Ghost fishing also affects non-target species including birds, turtles, marine mammals and elasmobranchs, some of which are endangered, threatened or protected, and contributes to pollution in a marine environment by introducing non-biodegradable synthetic plastic materials into the marine food chain, including microscopic plastic material and derived toxic chemicals of fishing equipment. The amount, distribution and effects of lost fishing gear have increased substantially in past decades with the rapid expansion of fishing effort and the use of synthetic, durable and buoyant materials. As a result of all these problems, marine pollution caused by nondegradable plastics has become one of the most serious problems worldwide.
This project implemented a pilot study in the Marine Protected Area of the Northern Littoral Marine Park, where degradable gillnets and trammel nets were provided to the fishing community in an unprecedented pilot test. The effect of this initiative on the reduction of ghost fishing and of synthetic plastic materials in the ocean was assessed. Alongside, a thorough study and update of the state of knowledge was conducted in order to determine the physical properties to be measured, the procedures to be adopted in the characterization of the degradation of biodegradable monofilaments, to promote the capacity building for producing fishing gear from selected biodegradable monofilaments, and to compare the fishing performance of nets made of conventional nylon and of the biodegradable material. Subsequently, the sustainability of using biodegradable materials versus conventional synthetic gear was assessed considering economic (costs and local economy), environmental (ecosystems health and biodiversity) and social (traditions and local practices) factors.
The project identified litter sources and evaluated the amount and nature present on beaches. The project also carried out community awareness actions about marine litter.
In recent years, many studies have shown that fishing nets made of polybutylene succinate resin blended with polybutylene adipate-co-terephthalate resin (PBSAT) can be naturally degraded in seawater within 2 years of being submerged and by then those gill nets would have become weak enough to stop catching fish. A series of interviews were carried out with local fishermen in order to define which types of nets are preferentially used at the local level. A survey was also carried out in the industrial environment, in order to ascertain the ability to manufacture nets with the selected biodegradable material. Suppliers were surveyed and specifications were drawn up. A survey was carried out on the fishing effort in the region (number of fishermen / type of vessel / gear used), a survey of the species caught and a survey of the industrial fabric associated with the supply of fishing gear. The market was prospected to estimate the price of nets made from conventional materials and the collection of opinion surveys from the fishing community.
The results indicate that PBSAT biodegrades in seawater, but the biodegradation process is slow enough to guarantee the efficiency of gill nets during their use and effective life cycle. The results also indicate PBSAT has good mechanical properties for fishing, especially when compared to conventional materials, such as polyamide, even when the material was used for a long period of time during experimental fishing campaigns, being exposed to different conditions at a mechanical and environmental.
The experience gained could serve as a basis for broader studies involving not only traditional fishing, but also coastal fishing, as well as different regions, expanding the scope of the study as much as possible, in order to increase its impact, its representativeness and its relevance.
On the other hand, the evaluation of the amount and nature present on beaches is crucial to take action against the sources of marine litter and help to design future management measures to tackle this challenge, based on systematic and consistent monitoring to provide decision makers with the evidence needed to take action.