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Small-scale crustacean fisheries in the English Channel have existed for centuries but have never been formally assessed; hence, concerns about their ecological and socio-economic sustainability could be raised. This study explores trends in this fishery's landings from 1901 to 2021, based on historical and recent landings data in two of the main administrative fishing divisions of the area, Cherbourg and Boulogne-sur-Mer quartiers. Crustacean fisheries were reported for both divisions from the beginning to the end of the time period considered, demonstrating that a dedicated crustacean fishery existed in the area since at least the 20th century. The species composition of the crustacean's catch (e.g., edible crab, Cancer pagurus Linnaeus, 1758; European lobster, Homarus gammarus (Linnaeus, 1758); European spider crab, Maja brachydactyla Balss, 1922) was almost impossible to track before the 2000s. Important fluctuations were observed in catch volume reports along time that might be related to two phenomena: technological advances that would have improved the fishery performances and the decline of some previously targeted species that might have led to a transfer in fishing effort. [ABSTRACT FROM AUTHOR]

Flamanville marine protected area (MPA) located in Normandy, France, was created in 2000 to sustain the local crustacean fishery. In 1985, an annual survey targeting crustacean populations (e.g. European lobster Homarus gammarus , edible crab Cancer pagurus , and European spider crab Maja brachydactyla) that include the future MPA started. The MPA implementation effects were investigated in this study. The sampling design allowed the integration of spatial and temporal covariances to estimate the MPA effects. With respect to the initial objective, the MPA significantly improves the most economically valuable species, H. gammarus , abundance. Lobster catch per unit effort increased by 597% in the MPA, whereas outside it only increased by 156%. The MPA creation also led to an increase in lobster size inside the protected area. Furthermore, a few years after the MPA implementation, lobster catches showed a significant non-linear decline with distance from the centre of the reserve, suggesting a spillover effect. However, the edible crab catches were halved following the MPA implementation suggesting an opposite effect. Spider crab abundance seemed unaffected. Finally, the MPA implementation had no effect on edible crab and spider crab sizes. These differential responses appear to result from these species' variable movement and competitive abilities. [ABSTRACT FROM AUTHOR]

Climate change has non‐linear impacts on species distributions and abundance that have cascading effects on ecosystem structure and function. Among them are shifts in trophic interactions within communities. Sites found at the interface between two or more biogeographical regions, where species with diverse thermal preferenda are assembled, are areas of strong interest to study the impact of climate change on communities' interactions. This study examined variation in trophic structure in the Celtic Sea, a temperate environment that hosts a mixture of cold‐affiliated Boreal species and warm‐affiliated Lusitanian species. Using carbon and nitrogen stable isotope ratios, trophic niche area, width, and position were investigated for 10 abundant and commercially important demersal fish species across space and time. In general, the niches of Boreal species appear to be contracting while those of Lusitanian species expand, although there are some fluctuations among species. These results provide evidence that trophic niches can undergo rapid modifications over short time periods (study duration: 2014–2021) and that this process may be conditioned by species thermal preferenda. Boreal species displayed spatial variation in trophic niche width and seem to be facing increased competition with Lusitanian species for food resources. These findings underscore the need to utilize indicators related to species trophic ecology to track the ecosystem alterations induced by climate change. Such indicators could reveal that the vulnerability of temperate ecosystems is currently being underestimated. [ABSTRACT FROM AUTHOR]

Global changes, through their impacts on ecosystem trophic structures, are behind regime shifts and cascading effects, and could result in the reorganization of whole ecosystems. The Celtic Sea is a temperate sea at risk of the above because of the interplay between climate change and fisheries. This sea has only displayed slight changes in species diversity between the late 20th century and the present day. However, this apparent stability in species diversity could be hiding structural transformations, including the rearrangement of trophic relationships. Historical stomach content database offers the opportunity to investigate changes in ecosystem trophic structure. Based on such database, this study explored shifts in the feeding habits of gadiform species in the Celtic Sea in the 1980s, 1990s, and 2010s. To this end, it examined dietary generalism and composition for four top predator fish species. During the target period, generalists maintained their diets, while specialists adopted more generalist diets. There were also decreases in frequencies of occurrence of certain fishes within the diets of gadiform species. These recent changes in trophic structure organization have likely been caused by the influence of global changes on both top-down and bottom-up processes that occurred in the Celtic Sea. • From the 1980s–2010s, specialists top predators in the Celtic Sea switched to generalist diets. • Fish occurrence decreased in the diets of top predators while crustaceans increased. • Top-down and bottom-up processes might have caused this trophic structure re-organization. [ABSTRACT FROM AUTHOR]

Bycatch species such as skates and rays are for most of them not subject to analytical stock assessment. However, their life history characteristics increased their vulnerability to fisheries. In the English Channel and North Sea area, the three main landed Rajidae species are Raja clavata , Raja brachyura and Raja montagui. The current management measure is a global TAC, common for all Rajidae species. Data to process analytical stock assessment are not available for these species, particularly discards data. A Bayesian multispecies biomass production model, following separately the landings and discards was applied to these stocks. This model provided proxies of reference points (MSY and B MSY) per species. All stocks were depleted in 1990 and are now rebuilding. However, rebuilding speeds are different within the complex, R. clavata being the fastest and R. brachyura the slowest. Furthermore, the proportion of the discards and landings to biomass differ between species, highlighting species specific fishing strategies. Differences in vulnerabilities within the Rajidae complex might be caused by the variability of life history parameters between species as well as landings and discards pattern differences. This second factor, usually not considered for data limited stock assessment, is particularly relevant for highly discarded chondrichthyans species, and might be considered when choosing new methodology to asses Rajidae stocks. [ABSTRACT FROM AUTHOR]