Explore the vast range of titles available.

Sustainable fisheries management requires regular scientific monitoring of fish stocks. When information on certain fish stocks is limited, environmental DNA (eDNA) holds promise to complement traditional monitoring surveys. However, a better understanding of how eDNA concentrations relate to fish abundance and biomass is needed. Here, eDNA quantification of two commercially important flatfish species in the North‐East Atlantic, common sole (Solea solea) and European plaice (Pleuronectes platessa), was assessed. First, species‐specific, probe‐based assays for plaice and sole targeting the mitochondrial cytochrome b and cytochrome c oxidase subunit I gene, respectively, were developed (for sole) and validated (for both species). Subsequently, two mesocosm experiments revealed a significant and positive relationship between both abundance and biomass and eDNA concentrations for both species at three eDNA emission time periods (5 min, 1 h, and 24 h). Larger plaice shed significantly more eDNA (copies L−1) than smaller conspecifics. Finally, eDNA was obtained from seawater collected during research surveys in the Belgian part of the North Sea in spring 2020 (i.e., local scale) and the southwestern North Sea in autumn 2020 and 2021 (i.e., regional scale). eDNA concentrations were compared to the observed abundance (individuals per km2) and fish density in terms of biomass (kg per km2) as observed in the trawl at the same station. Local eDNA concentrations of both sole and plaice were positively correlated with observed abundance and fish density. The correlation between regional eDNA concentrations and fish density was positive and significant for sole in 2020 and 2021 and for plaice in 2020, but not in 2021. The correlation between regional eDNA concentrations and observed abundance was positive and significant for sole and plaice in 2020, but not in 2021. These results illustrate the potential of eDNA to estimate abundance and biomass parameters for stock assessments of flatfishes in the North Sea. In this study, eDNA shedding of two commercially important flatfish species in the North‐East Atlantic, common sole (Solea solea) and European plaice (Pleuronectes platessa), was assessed in both controlled and natural environments. Our results contribute to a growing body of evidence that eDNA concentrations often positively correlate with abundance and biomass, under controlled conditions and using field samples. We highlight the potential and challenges of eDNA as a reliable method to improve current stock assessments of flatfishes in the North Sea.

This study investigates the implications of spatial management strategies on fish populations and fisheries across EU waters, particularly focusing on establishing potential areas for fishing closures to protect nurseries, benthic communities, and biodiversity hotspots in the Northeast Atlantic and Mediterranean Sea. The research addresses the effectiveness of prohibiting certain fishing practices in the context of the EU Common Fisheries Policy (CFP). We investigate spatial- and effort-based fisheries management strategies based on spatial ecosystem modelling, which provides insights into species interactions and distribution shifts, and bioeconomic fisheries models which incorporate finely defined fishing fleets and economic dynamics. Our findings emphasize that redistributing fishing effort without reducing overall effort and catches may negate intended decreases in mortality rates of sensitive marine species or restoration of vulnerable marine habitats to the status targeted by the European marine legislation (EU Marine Strategy Framework Directive MSFD). We highlight the complex interplay of social, economic, ecological, and institutional factors influencing fishers’ decision-making in effort displacement. As the proportion of closed regions increases, potential effects on marine ecosystems can even be damaging in the short term to some sensitive species (such as the endangered, threatened and protected species ETP) and vulnerable habitats (with currently high relative benthic status RBS). This emphasizes the importance of the placement of closed areas and of combining area-based management with other fishery management measures. Findings from case studies in the North Sea, Mediterranean Sea, and Bay of Biscay indicate that prohibiting certain fishing practices in designated areas will likely induce short-term economic losses on specific fishing fleets. Where the prohibitions contribute to improved selectivity or productivity of the fish stocks, these losses may be regained in the long term. Finally, the long-term benefits for marine life that are expected through the spatial protection of vulnerable life stages and habitats will rely on the extent to which climate change affects ocean productivity and distribution of species and habitats.

This paper combines fisheries dependent data and environmental data to be used in a machine learning pipeline to predict the spatio-temporal abundance of two species (plaice and sole) commonly caught by the Belgian fishery in the North Sea. By combining fisheries related features with environmental data, sea bottom temperature derived from remote sensing, a higher accuracy can be achieved. In a forecast setting, the predictive accuracy is further improved by predicting, using a recurrent deep neural network, the sea bottom temperature up to four days in advance instead of relying on the last previous temperature measurement.