Projet CELSELEC. Amélioration de la sélectivité des chalutiers hauturiers en mer Celtique

In the context of the new European Common Fisheries Policy and in particular the Landing Obligation, this report synthesizes the trials which were carried out between 2014 and 2016 on French bottom trawlers operating in the Celtic Sea and Western Channel, to decrease their discards. All the detail of the experiments and their results are attached in the voluminous appendices. After a state of the art and various workshops organized in partnership between fishermen, equipment manufacturers and scientists, 3 basic devices were selected for the trials, according to the main fisheries: - 100 mm square meshes cylinder - SMC - (in addition to the mandatory 100mm and 120 mm square mesh panels - SMP) with or without scaring floats ; - Extension + codend in meshes turned by 90° ("T90") 100 mm mesh size ; - Monkfish / Skates / Megrim grid (semi-elliptic). Preliminary experiments were carried out in flume tank and at sea and 38 sea cruises were then realized during three years, with observer on board. The use of the T90 meshing in the extension and codend offers an answer to the problem of choke species for fishing fleets operating on the West of the Celtic sea, by reducing appreciably the catches of boarfish, mackerel and horse mackerel, which can represent important volumes in punctual and not predictable catches (75-85 % reduction of the discards in weight). The interest of this device is also demonstrated to reduce the catches of young Gadidea, mainly haddock and whiting. Losses of these commercial species can exist in some cases, but these volumes do not seem to affect the very positive perception by the skippers of the use of this type of trawl. The implementation of this technique is simple and the global reduction of the volume of catches allows on one hand to limit the work of sorting on board and on the other hand to improve the quality of the valued part. It is important to note that the results are homogeneous in the various situations of use (boat, fishing zone, season …). The recognized efficiency of trawls equipped with an extension in 100mm T90 meshes led to an extension of their use for the fleet operating in Celtic Sea. The results obtained for the 100mm square mesh cylinder are less marked, even if the escape of the small individuals of Gadidea seems improved. The adjustment of the positioning of the device remains difficult to define and follow-up studies should be led to optimize the technical configurations. In the same way, the interest of the use of a scaring device remains to demonstrate. For the last prototype of supple monkfish grid tested (version 4 in the report), a global decrease of 20 % of the weight of discards is observed, without decrease of the landings. We notice in particular a decrease of the discards of flatfish (megrims, scaldfish) but also of gurnards, dragonets and small dogfishes. Concerning anglerfish, escapes are noticed for the small sizes (between 10 and 20cm), but it does not allow to reveal a significant difference of the discards in weight.