Acronym RAI-AP-76/2007
Category
Fisheries
Title Informe del seguimiento científico de la acción piloto RAI/AP-76/2007: pesca experimental con arte de arrastre de fondo en Mallorca (Islas Baleares, Mediterráneo Occidental) - RAI-AP-76/2007: Experimental fishing with bottom trawl gear in Mallorca (Balearic Islands, Western Mediterranean) Programme National Programme
Instrument (FP6)
Contact Type (FP7)
Strand (Interreg)
NA
Theme (FP7)
Activity Area (FP6)
Regional Area (Interreg)
Action (COST)
NA
Specific Programme (FP7)
NA
Funding source National Coordinator Enric Massuti Coordinator email enric.massuti@ba.ieo.es
Coordinator institution
IEO - Spanish Institute of Oceanography (Spain)
Institutions involved
NA
Start year 2008 End year 2009 Funding (€) € 172,600 Website http://www.repositorio.ieo.es/e-ieo/bitstream/handle/10508/992/RAI-AP-76-2007.pdf?sequence=1&isAllowed=y Summary From 14 October to 28 December 2008, 49 experimental bottom trawlers have been carried out, on board the R/P Punta d'es Vent, in fishing grounds on the shelf and slope of southern Mallorca (Balearic Islands). Two fishing gears were used, alternately. The traditional "beam trawler" net, used by this and other trawlers in the area, weighing 900 kg and a 40 mm rhombic mesh codend, coupled to 360 m of mallets and multipurpose classic oval doors weighing 670 kg. An experimental net, whose weight was estimated at 800 kg, made of finer cloths and with a larger mesh opening in the body and sleeve and a 40 mm square mesh codend, coupled to 310 m of mesh and EXPLORER doors of 588 kg. Of the total catches, 43 were considered valid for data analysis, based on three bathymetric strata: deep platform (80-200 m), upper slope (300-500 m) and middle slope (600-800 m), whose The main target species were hake (Merluccius merluccius), Norway lobster (Nephrops norvegicus) and red shrimp (Aristeus antennatus), respectively. The composition of the standardized catch (kg/h and n/h) and the average rates of total catch, discards and landings, and of the target species, by bathymetric stratum and gear, have been estimated. The size distributions of the captured specimens were also calculated, as well as their marketed and discarded fraction, and for the three target species the curves and selection parameters were modeled with a 40 mm square mesh codend. With the SCANMAR system, parameters of the gear working on the bottom were estimated (distance between doors, inclination and angles of attack of doors, tension in doors and ridges, horizontal and vertical opening of the net, symmetry and filtering of the net at the mouth, beam and start of the codend) and with a flow meter the fuel consumption during fishing was recorded. In each trip, the unloaded biomass and its first-sale economic value were estimated, as well as the operating costs related to fuel consumption. The analysis of this information has been carried out using univariate and multivariate techniques.
The results have shown that the geometry change in the codend mesh (from rhombic to square) improves the selectivity of the trawl fishery: first catch sizes are increased (Merluccius merluccius: from 10.6 to 13.4 cm TL with rhombic mesh and square of 40 mm, respectively; Nephrops norvegicus: 15-19 to 23.2 mm LCT; Aristeus antennatus: from 17.2 to 20.0 mm LCT) and discards are reduced (Merluccius merluccius: from 135.6 to 55.6 specimens/h with rhombic and square mesh of 40mm, respectively). The experimental art has also made it possible to reduce the direct impact on the seabed, not only due to the reduction in the weight of the net and the doors ('11-12%) but also in the contact surface of the doors. As a consequence, the distance between doors ('7%) and the horizontal opening of the net ('10%) have been maintained, and even increased, with a lower main engine rpm during fishing ('3 %) and, therefore, fuel consumption ('11%). The better selectivity and greater energy efficiency of the experimental art compared to the traditional one have been obtained without a significant loss of commercial yields, in most cases. However, a negative aspect of experimental art must also be noted.
Goals: Evaluate, under commercial conditions, the feasibility of a trawl gear design, with the aim of: (1) Reducing its physical impact on the seabed, and with it the negative effect on exploited ecosystems; (2) Reduce the fuel consumption of the vessel, which would reduce CO2 emissions into the atmosphere and increase the cost-efficiency ratio of the activity; (3) Improve the selectivity of the fishery, without a decrease in its economic performance.
Keywords
Bycatch;
Fish;
Hake;
Environmental impact;
Discard;
Gear selectivity;
Fishing technology;
Trawling;
Shellfish;
Lobster;
Physical disturbance;
Catch;
Crustacean;
Gear technology;
Shrimp;
Marine Region
54
Balearic Island (GSA 5)
1
Marine Region Map
