Abstract
Most European fishing fleets will need to drastically reduce their unwanted catches to comply with new rules of the common fisheries policy. A more practical way to avoid increasing on-board sorting time and issues linked to storage capacity is to prevent unwanted catches in the first place. We assessed the selectivity properties of an experimental fishing gear that combined a 100 mm T90 cylinder with 130 meshes in the extension and a 100 mm T90 codend of 33 meshes (experimental gear) compared to a 100 mm diamond mesh extension and codend (control gear) during commercial trips using twin trawls. Analysis of the relative size composition of catches indicated a significantly higher escapement of small fish of several target species (e.g. Lepidorhombus whiffiagonis, Melanogrammus aeglefinus, Raja spp, and Lophius spp) and non-target species (e.g. Capros aper and Gurnards spp) from the T90 experimental trawl compared to the control trawl (n = 49 hauls), resulting in a significant reduction of unwanted catches of Gadidae, Triglidae, and Caproidae. In contrast, non-negligible commercial losses of small grade target gadoid species were observed. Mixed general linear models showed that the proportion of ray, haddock and anglerfish retained per length class decreased with increased tow duration. The T90 experimental gear will perform at a commercial level when targeting monkfish, megrim, rays and large haddock, however fishers are not likely to use this gear when targeting smaller-bodied species such as cephalopods, small haddock, whiting (Merlangius merlangus) and hake (Merluccius merluccius), because the gear is likely to allow large numbers to escape. Selectivity studies often focus on a short list of target species; however, catches of non-target species under quota can be problematic for some fisheries. For example, under the implementation of the Landing Obligation catches of boarfish could choke the French whitefish demersal fisheries in the Celtic sea, as France has no national quota for that species. The device tested constitutes an efficient solution to mitigate catches for such non-target schooling fish.
Highlights
The European Union common fisheries policy, which regulates fishing activities in European waters, was reformed in 2013, resulting in a new regulation, including article 15 on the landing obligation [1]. It stipulates that all catch from the stocks under total allowable catch (TAC) or minimum conservation reference size (MCRS) regulations must be landed, prohibiting the common practice of throwing unwanted catches back into the sea
To the best of our knowledge, this was the first time a 100 mm T90 mesh configuration was tested simultaneously in the extension and codend, T90 mesh has been individually tested in the codend [10, 16, 22] or the extension [14]
The device aims to reduce, as much as possible, catches of target species below the MCRS and all sizes of non-target species. It should drastically decrease the overall amount of unwanted catches that fishers previously discarded and should store on-board and land in port to comply with the new common fishery policy regulation
Summary
The European Union common fisheries policy, which regulates fishing activities in European waters, was reformed in 2013, resulting in a new regulation, including article 15 on the landing obligation [1]. It stipulates that all catch from the stocks under total allowable catch (TAC) or minimum conservation reference size (MCRS) regulations must be landed, prohibiting the common practice of throwing unwanted catches back into the sea. These discarding practices represent a substantial protein waste and may lead to unsustainable management of marine resources [2]. Variability in fish behavior among areas, seasons [6, 7] and in the net depending on gear configurations such as vertical openings [8, 9], prevent straightforward extrapolation of results to other case studies
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