Influence of the change of trawling otter boards on demersal species’ catches
-
1
Facultad de Ciencias, Universidad de Alicante, Spain
Mediterranean fisheries are characterized by being multi-specific and having several target species. In terms of the number of vessels and total catch, one of the most important fleets is demersal trawling. This fishery has a particularly complicated management due to its environmental impact and low selectivity. Along the Spanish Mediterranean, its main target species are the European hake (Merluccius merluccius), the red shrimp (Aristeus antennatus), blue whiting (Micromesitius poutassou), mullets (Mullus spp.) and Norway lobster (Nephrops norvegicus).
Demersal fisheries in the Mediterranean Sea are heavily overfished and, the Common Fisheries Policy has tried to improve its sustainability. One of its measures are subsidies of any modification of a fishing gear which improves selectivity, reduces environmental impact or fuel consumption but in any case, this modification must increase the fishing effort on target species ((UE) 508/2014).
One of the modifications which have benefited from these subsidies are pelagic otter boards. These otter boards reduce the impact on the seafloor and fuel consumption but their effect on the catches of target species has not been assessed.
To this end, five vessels of three different ports of Alicante (Denia, Altea and Santa Pola) which changed their conventional trawling otter boards to pelagic ones were studied and compared with five vessels of the same characteristics which did not change their otter boards. Landings of 10 days during two years before the otter board change and two years after the change were compared to assess its influence in catch composition. The nMDS did not show differences in capture composition due to the high variability of trawling catches shadowing the possible effect of otter boards. An analysis of variance (ANOVA) was performed to assess differences in total daily catch and for the 5 main species of each port.
ANOVA did not show significant differences in total landing weight in Santa Pola and Altea although, in Santa Pola, pelagic otter boards seem to increase their captures compared with conventional ones. In the case of Denia, the interaction between the Before/After and the otter board type factors was significant, which means captures increased after installing the pelagic otter boards. These results show that the effect of pelagic otter boards could depend on the target species. In Denia, the main target species was the red shrimp, which showed a marginally significant (p<0.1) increase in catches in boats using pelagic otter boards, becoming a possible sensible species to the otter board modification. Probably the pelagic otter boards may expand the net opening which could increase catchability on certain species making this modification a possible negative effect on demersal species despite the benefits of fuel consumption and the lower environmental impact on the sea bottom.
Keywords:
Mediterranean fisheries,
Demersal trawl,
Otter board,
catchability,
Fisheries Management
Conference:
XX Iberian Symposium on Marine Biology Studies (SIEBM XX) , Braga, Portugal, 9 Sep - 12 Sep, 2019.
Presentation Type:
Poster Presentation
Topic:
Fisheries, Aquaculture and Biotechnology
Citation:
Blanco Murillo
F and
Sánchez Lizaso
JL
(2019). Influence of the change of trawling otter boards on demersal species’ catches.
Front. Mar. Sci.
Conference Abstract:
XX Iberian Symposium on Marine Biology Studies (SIEBM XX) .
doi: 10.3389/conf.fmars.2019.08.00121
Copyright:
The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers.
They are made available through the Frontiers publishing platform as a service to conference organizers and presenters.
The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated.
Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed.
For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions.
Received:
09 Jun 2019;
Published Online:
27 Sep 2019.
*
Correspondence:
Mr. Fabio Blanco Murillo, Facultad de Ciencias, Universidad de Alicante, Alicante, Spain, fabio.blanco@ua.es