Guarding net effects on landings and discards in Mediterranean trammel net fishery: Case analysis of Egadi Islands Marine Protected Area (Central Mediterranean Sea, Italy)

Abstract

Discards remain among the main negative impacts of fishing activities, and their reductions are strengthened by the European Common Fisheries Policy (European Regulation 1380/2013). Trammel net fisheries appear more sustainable compared with other fishing techniques, especially from an ecological viewpoint. Despite this, reports show that trammel net fisheries deliver discard quantities between 10% and 43% of the total catch biomass. To supplement existing information, this current work attempts to address the discard reduction using guarding net in the small-scale fisheries of Egadi Islands MPA (Western Sicily, Central Mediterranean Sea). To assess the reduction of unwanted catches, 48 experimental fishing trials were conducted within a 6-month period. The experimental fishing trial employed a trammel net made up of 20 panels alternated with two different net configurations. The control panels (CN) held a large outer (180 mm) and small inner (31.25 mm) meshes. The test panels (GN) with guarding net constituted a three-mesh-high (50-mm mesh size) net placed between trammel net panels and a lead line. A total of 3,310 individuals belonging to 106 taxa and nine phyla were caught. Crustaceans were the most abundant unwanted catches in the control panels, whereas bioconstructions occurred in the guarding net panels. The discard ratios of CN and GN panels were statistically different (t-value = –2.55; p< 0.05). The analysis of catch per unit effort showed higher catches of CN panels for both commercial and discard fractions (p< 0.05). Moreover, the guarding net panels caught the main discarded species at 20% lower compared with the control. The overall value of the catch at the CN panels (€ 3,366.90) was higher than the total income (€ 2,043.70) generated using the GN panels, which suggests a significant commercial loss of 40% (p< 0.05).

Reducing Artisanal Fishery Impact on Marine Community: New Data from Comparison of Innovative and Traditional Gear

“…On the other hand, no difference recorded between gears was statistically significant in terms of overall catch, also considering the benthic organisms. Although our results are in accordance with [28], they are in contrast with those reported in Mersin Bay [32], where the use of a guarding net on the lead line of shrimp trammel nets reduced the discard, and in Favignana, where [30] a gear composed of a trammel net panel alternated by a guarding net panel was tested. Moreover, except for some studies where the use of guarding net reduced discard without affecting the catch [13,33], it also reduced the commercial catch [30,31].…”

“…Although the guarding net seemed improve the selectivity for elasmobranchs, this result could adversely affect fishers' perception on the effectiveness of this net in sites such as Favignana, where some cartilaginous fish have a good commercial value [30,31]. Indeed, in Favignana, species such as M. mustelus, M. punctulatus and some species of Raja and Torpedo, are usually sold and are targets of fishing with trammel net; however, in the present study, these species were included in the commercial fraction in this area.…”

Mitigating bycatch in Mediterranean trammel net fisheries using species-specific gear modifications

“…However, the fraction of benthic invertebrates of the total catch in the current study was fairly low (about 10%), and so the lack of success of all types of modified nets in mitigating their catch had no impact on the surveyed métier. As stated in the Introduction, the use of the guarding net has been ambiguous since, with the exception of a few situations where it reduced discards without affecting catch [19,21], in most cases it lowered both commercial catch and discards [23][24][25], while in some cases it had no effect on catch at all [20]. We hypothesize that variations in guardingnet efficiency are mostly caused by the species profile of the discards.…”

“…[19,21,22]), even though in most cases the reduction in discards is accompanied by an equivalent fall in commercial catches (e.g. [23][24][25]), or even cases where nor commercial catch neither discards were affected by the guarding net [20].…”

Escape Survival and Scale Damage Assessment of Red Mullet (Mullus barbatus Linnaeus, 1758) during Bottom Trawling in the Central Mediterranean Sea

“…EU 1380/2013 [9] encourages improving the selectivity of the fishing gear. Therefore, in recent years, physical modifications such as by-catch reduction devices (BRDs) have been tested to improve species selection, e.g., [10][11][12][13][14]. In some cases, compared to conventional gear, these latter sorts of BRDs have been demonstrated to mitigate problematic by-catches [10,11,15,16].…”