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| Mouchet, Maud; Poirson, Manon; Morandeau, Fabien; Vogel, Camille; Méhault, Sonia; Kopp, Dorothee. |
| Improving the selectivity of a fishing gear is one technical management measure to significantly reduce by-catch of non-commercial species or undersized individuals. The efficiency of selective device is mainly estimated by comparing species composition, the biomass and length spectrum of caught individuals and escapees while the functional traits of species are rarely accounted for. Using an innovative technical device to reduce catches of undersized individuals in a multispecific bottom trawl fishery in the Bay of Biscay, namely a T90 mesh cylinder, we measured functional traits on both caught and escaped individuals of 18 species. Using a Principal Component Analysis and K-means partitioning, we clustered species into 6 groups illustrating 6 different... |
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| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00512/62330/66588.pdf |
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| Kopp, Dorothee; Morandeau, Fabien; Mouchet, Maud; Vogel, Camille; Mehault, Sonia. |
| In the Bay of Biscay, the selective properties of otter trawls have mainly been studied with regard to single species. However, for bottom trawl multispecific fisheries targeting fish, it remains challenging to find a selective device capable of limiting catches of small individuals of several species without commercial losses. The present study focuses on an innovative technical solution to reduce catches of undersized individuals in a multispecies bottom trawl fishery in the Bay of Biscay. We tested a cylinder made of 100-mm diamond meshes turned at 90°, namely T90 inserted in the extension piece. We present the selectivity results obtained for six commercial species. This device allows the escape of small Solea solea, Trachurus trachurus and... |
| Tipo: Text |
Palavras-chave: Gear technology; Covered codend; Turned mesh; Escape; Discard ban. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00439/55026/56487.pdf |
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| Merillet, Laurene; Mouchet, Maud; Robert, Marianne; Salaun, Michele; Schuck, Lucie; Vaz, Sandrine; Kopp, Dorothee. |
| Trawling activities are considered to be one of the main sources of disturbance to the seabed worldwide. We aimed to disentangle the dominance of environmental variations and trawling intensity in order to explain the distribution of diversity patterns over 152 sampling sites in the French trawl fishing-ground, the Grande Vasière. Using a towed underwater video device, we identified 39 taxa to the finest taxonomic level possible, which were clustered according to their vulnerability to trawling disturbance based on functional traits. Using generalized linear models, we investigated whether the density distribution of each vulnerability group was sensitive to trawling intensity and habitat characteristics. Our analyses revealed a structuring effect of depth... |
| Tipo: Text |
Palavras-chave: Bay of Biscay; Biodiversity; Bottom trawl; Fishing; Underwater video; Vulnerability. |
| Ano: 2018 |
URL: http://archimer.ifremer.fr/doc/00406/51741/52436.pdf |
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| Merillet, Laurene; Kopp, Dorothee; Robert, Marianne; Salaun, Michele; Mehault, Sonia; Bourillet, Jean-francois; Mouchet, Maud. |
| The development of the vessel monitoring system (VMS) in the recent years has offered high-resolution data to map the distribution and intensity of fishing activities and contributed to enhancing the potential identification of fishing impacts. However, impacts could vary at very small scale and the resolution of VMS data might not be fine enough. Other proxy could be used, such as trawl marks visible on the seabed observed by underwater video or side-scan sonar to evaluate small-scale trawling effort. In the Bay of Biscay, an underwater video survey of the Nephrops norvegicus fishing ground was conducted and provided environmental characteristics such as depth and number of trawl marks at 152 transects. The relevance of observed trawl marks as a... |
| Tipo: Text |
Palavras-chave: Bay of Biscay; Fishing intensity; Sediments; Underwater video; Vessel monitoring system. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00410/52112/52854.pdf |
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| Merillet, Laurene; Robert, Marianne; Salaun, Michele; Schuck, Lucie; Mouchet, Maud; Kopp, Dorothee. |
| Based on towed underwater videos, diversity patterns and their main environmental and anthropogenic drivers were assessed in the “Grande Vasière” (northeast Bay of Biscay), one of the main French fishing grounds. The density of bentho-demersal megafauna was recorded along 152 transects in this area in 2014. The highest number of taxa and densities were observed on the external margin of the Grande Vasière, in deep areas with low fishing intensity. The highest levels of taxa evenness were located on the central and coastal parts that are shallower and exposed to medium to high trawling intensity. Multivariate analysis identified four different communities driven by fishing intensity, depth, sediment type and bottom current speed. We distinguished three... |
| Tipo: Text |
Palavras-chave: Biodiversity patterns; Indicator species; Fishing and environmental variables. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00441/55261/56796.pdf |
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