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Benthic fishing gear is considered one of the techniques with the greatest impact, which generates high amounts of bycatch, which include both unwanted invertebrate species and juveniles of commercial species. These two components are usually discarded in large quantities due to their low commercial value or their commercialization is prohibited. In the case of juveniles of species regulated by Annex III of the Mediterranean regulation (EU Reg. 1967/2006), their discarding is prohibited due to the entry into force of the landing obligation (EU Reg. 1983/2013, Article 15). Currently, the fishing gear used in the Mediterranean and in Europe in general is based on non-biodegradable plastic materials, mainly from the polyethylene (PE) and polyamide (PA) families. These materials are persistent in the marine environment and generate two main problems:

(i) in the short term, when nets are lost or abandoned, they continue to fish (ghost fishing) with a negative impact on vulnerable species or protected habitats;

ii) its slow degradation contributes in the medium to long term to the problem of plastic pollution in the marine environment. Directive (EU) 2019/904 of the European Parliament and of the Council aims to reduce the impact of certain plastics in the aquatic environment, and applies to fishing gear containing plastic, which is currently entirely plastic
(Articles 2 and 3).

A1 – COLLECTION AND ANALYSIS OF EXISTING
INFORMATION A2 – EXPERIMENTAL WORK
A3 – IDENTIFICATION AND QUANTIFICATION OF BIOLOGICAL
MATERIAL A4 AND A5 – STATISTICAL ANALYSIS
A6 – SOCIOECONOMIC IMPACT
A7 – PRESENTATION OF THE PROJECT AND DISSEMINATION OF RESULTS

Benthic fishing gear is one of the techniques with the greatest impact on the seabed, generating high amounts of bycatch, which include both unwanted invertebrate species and juveniles of commercial species. The construction of fishing nets is based on plastics that do not degrade (polyethylene and polyamides), whose loss at sea generates incidental mortality for an indefinite time (“ghost fishing”). Plastic waste generated by the fishing industry accounts for around 10% by weight of marine macro litter worldwide. These lost or abandoned fishing gears at sea are especially relevant from an ecological point of view, both because of the low biodegradability of the materials with which they are built (synthetic polymers, steel, etc.), which implies a long life in the environment, and because of the design itself, aimed at capturing living beings.

The INARBIO project aimed to evaluate the feasibility in terms of fishing efficiency of replacing the usual nets, mainly plastics of the polyethylene and polyamide families, with the plastic material PBSAT (a resin, developed and marketed under patent by the company S-ENPOL -SAMSUNG group- of South Korea). This material is entirely biodegradable by the natural action of marine microorganisms over a period of 2 to 3 years. The entire commercial fishing sampling protocol in the INARBIO project was adapted to the usual working conditions of the trammel operators in the study areas (Region of Murcia and Valencian Community), to evaluate the effectiveness of a trammel made with PBSAT in real conditions.

The analysis of the results of the experimental fishing indicates that the trammel net built with PBSAT generates a lower volume of catches (loss of 12% in Murcia and 20% in Alicante, by weight). However, for certain commercial species such as sea bass, red mullet or pagel, catches with trammel in PBSAT were statistically higher. On an ecological level, this new trammel net generated fewer discards and captured a smaller proportion of vulnerable species, suggesting that it has less impact on the seabed than the traditional trammel net. From an economic point of view, the profitability analysis revealed an immediate loss of 11 to 12% of the capture in value with PBSAT art. This loss, together with the higher cost of manufacturing trammel with PBSAT, would result in a decrease in economic benefits of around 45%, which may be a major barrier to the widespread adoption of this new biodegradable material among a sector, the artisanal fishing sector, with little economic profitability in recent decades.

In summary, the study shows that the adoption of a trammel with PBSAT (or equivalent biodegradable materials) would significantly reduce negative impacts of fishing such as ghost fishing or plastic pollution, but economic support measures should be adopted to facilitate its widespread adoption by the fishing sector.