No abstract

A large body of knowledge exists on individual anthropogenic threats that have an impact on marine biodiversity in the Mediterranean Sea, although we know little about how these threats accumulate and interact to affect marine species and ecosystems. In this context, we aimed to identify the main areas where the interaction between marine biodiversity and threats is more pronounced and to assess their spatial overlap with current marine protected areas in the Mediterranean. Mediterranean Sea.\ud We first identified areas of high biodiversity of marine mammals, marine turtles, seabirds, fishes and commercial or well-documented invertebrates. We mapped potential areas of high threat where multiple threats are occurring simultaneously. Finally we quantified the areas of conservation concern for biodiversity by looking at the spatial overlap between high biodiversity and high cumulative threats, and we assessed the overlap with protected areas.\ud Our results show that areas with high marine biodiversity in the Mediterranean Sea are mainly located along the central and north shores, with lower values in the south-eastern regions. Areas of potential high cumulative threats are widespread in both the western and eastern basins, with fewer areas located in the south-eastern region. The interaction between areas of high biodiversity and threats for invertebrates, fishes and large animals in general (including large fishes, marine mammals, marine turtles and seabirds) is concentrated in the coastal areas of Spain, Gulf of Lions, north-eastern Ligurian Sea, Adriatic Sea, Aegean Sea, south-eastern Turkey and regions surrounding the Nile Delta and north-west African coasts. Areas of concern are larger for marine mammal and seabird species.\ud These areas may represent good candidates for further research, management and protection activities, since there is only a maximum 2% overlap between existing marine protected areas (which cover 5% of the Mediterranean Sea) and our predicted areas of conservation concern for biodiversity

Much of the economic profitability of fishing the high seas is dependent on government subsidies.

As part of the global marine fisheries catch reconstruction project conducted by the Sea Around Us over the last decade, estimates were derived for discards in all major fisheries in the world. The reconstruction process derives conservative but non-zero time-series estimates for every fisheries component known to exist, and relies on a wide variety of data and information sources and on conservative assumptions to ensure comprehensive and complete time-series coverage. Globally, estimated discards increased from under 5 million t/year (t = 1,000 kg) in the early 1950s to a peak of 18.8 million t in 1989, and gradually declined thereafter to levels of the late 1950s of less than 10 million t/year. Thus, estimated discards represented between 10% and 20% of total reconstructed catches (reported landings + unreported landings + unreported discards) per year up to the year 2000, after which estimated discards accounted for slightly less than 10% of total annual catches. Most discards were generated by industrial (i.e. large-scale) fisheries. Discarding occurred predominantly in northern Atlantic waters in the earlier decades (1950s-1980s), after which discarding off the West Coast of Africa dominated. More recently, fleets operating in Northwest Pacific and Western Central Pacific waters generated the most discards. In most areas, discards consist essentially of marketable taxa, suggesting a combination of poor fishing practices and poor management procedures is largely responsible for the waste discarding represents. This is important in an era of increasing food security and human nutritional health concerns, especially in developing countries. K E Y W O R D Scatch estimation, catch reconstruction, ecosystem effects of fishing, fisheries impacts, overfishing, unreported catch

Abstract:The mean trophic level (TL) of fish landed in fisheries on the east and west coasts of Canada is declining by 0.03-0.10·decade -1 , similar to global trends. This finding is based on data from United Nations Food and Agriculture Organization and the Canadian Department of Fisheries and Oceans and other Canadian sources for the period 1873-1997. Significant rates of decline in mean TL were obtained even when key species -Atlantic cod (Gadus morhua) on the east coast and Pacific herring (Clupea pallasi) and Pacific hake (Merluccius productus) on the west coast -were omitted from the analysis. Fish taken in inland water fisheries did not exhibit a decline in mean TL. Two models were developed, based on length and age, respectively, for correcting TL estimates of individual species for the effects of changes in body size due to changes in fishing mortality. Both produced corrections that were small relative to changes in mean TL that resulted from changes in species composition of the catch over time. Overall, these results suggest that the mean TL of fish landed can be used as an index of sustainability in multispecies fisheries and that its reliability will depend on the quality of the data and length of the time series available for analysis.Résumé : Le niveau trophique (NT) moyen des poissons débarqués dans les pêches des côtes est et ouest du Canada baisse de 0,03 à 0,10 par décennie, comme c'est le cas dans les tendances mondiales. Ce constat se fonde sur des données de l'Organisation des Nations Unies pour l'alimentation et l'agriculture (FAO), du ministère des Pêches et des Océans du Canada et d'autres sources canadiennes, pour la période allant de 1873 à 1997. Des taux significatifs de dé-clin du NT moyen ont été obtenus même lorsque des espèces clés -morue franche sur la côte atlantique, hareng et merlu sur la côte pacifique -étaient omises dans l'analyse. Les poissons capturés dans les eaux intérieures ne présen-taient pas de baisse du NT moyen. Deux modèles ont été construits, basés respectivement sur la longueur et sur l'âge, pour corriger les estimations du NT de chaque espèce de façon à tenir compte des effets des changements de la taille corporelle dus à des changements dans la mortalité par pêche. Les deux modèles ont produit des corrections qui étaient petites par rapport aux changements dans le NT moyen dus à des modifications de la composition spécifique des captures au fil du temps. Globalement, ces résultats permettent de penser que le NT moyen des poissons débarqués peut être utilisé comme un indice de durabilité dans les pêches plurispécifiques, et que sa fiabilité dépendra de la qualité des données et de la longueur des séries chronologiques disponibles pour les analyses.[Traduit par la Rédaction] Invited perspectives and article 62