Eric Foucher

Modelling larval dispersal of Pecten maximus in the English Channel: a tool for the spatial management of the stocks

The great scallop Pecten maximus supports one of the most important and valuable commercial fisheries around the British Isles and in the northwest of France, but the resource is mainly managed at the scale of each local fishing ground through a combination of European, national and local measures. To analyse the larval dispersal pathways and connectivity patterns among fishing grounds of the great scallop in the Celtic Sea and the English Channel, a particle tracking model was developed. The model combined a 3D physical circulation model that simulated currents and temperature fields and a scallop larval submodel that took into account a temperature-dependent planktonic larval duration and an active vertical swimming behaviour. Due to the lack of stock assessment at the regional scale, the location of the main fishing grounds was established by combining different sources (e.g. grey literature, unpublished scientific surveys, vessel monitoring data, fishermen) while the spawning biomass of each stock was estimated from landings data. Results indicated that each local stock could not be considered as a single independent management unit and that all stocks except that of the Bay of Brest were connected to neighbouring stocks, suggesting that the management should be defined in a metapopulation context. Three major groups of strongly interconnected stocks including two or three stocks exhibiting high retention and self-recruitment rates and some peripheral stocks with a low self-recruitment rate were defined: the North Brittany and Channel Islands, the eastern English Channel, and the SW of England. Our results were discussed in terms of the definition of management units in comparison with genetic and phenotypic data, and in terms of resource management in a transnational context.

Stock structure of the English Channel common cuttlefish Sepia officinalis (Linnaeus, 1758) during the reproduction period

Within the English Channel, the common cuttlefish Sepia officinalis is a semelparous species for which a 2-year life cycle was exclusively described in the 1980s. In the 1990s, new research indicated that whilst a 2-year life cycle was still evident for females and the large majority of males, a small proportion of males were actually maturing at only 1 year of age. Since 1980, the interest of French and UK fishers for this resource has increased and it is nowadays one of the most important demersal species of the area and is considered to be fully exploited. From the start of the 20th century, fishing effort and sea surface temperatures have increased in the English Channel and have probably impacted the life history traits of S. officinalis . A 2-year sampling programme was undertaken at French landing sites of the English Channel during the reproduction season in 2010 and 2011 to estimate if the proportion of 1-year-old mature animals has changed. Age determination was carried out by coupling polymodal decomposition and lipofuscin measurement. Size-at-maturity for each year and each sex was estimated by fitting a binomial error GLM. Results highlight that a variable percentage of males and females belonging to the first cohort are mature and that size-at-maturity was lower than that observed in the 1990s. Finally, different parameters, such as temperature and fishing pressure are explored to discuss changes in life history traits suggesting that cuttlefish could be an indicator of the temperature regime shift in the English Channel.

The Channel Programme: A Large-Scale Integrated Approach

The Channel programme is a collation of interlinked multidisciplinary projects supporting ecosystem-based management in the English Channel by integrating works carried out in the past thirty years including novel approaches to the spatial modelling of ecosystems. The Channel programme has required a coordination of efforts and expertise by both scientists and stakeholders to address the challenges of the Marine Strategy Framework Directive and of its national implementations. The Channel programme has also consisted of harmonising information, regulations and habits in terms of ecosystem management in the English Channel.

Communication de l’information géographique maritime et côtière pour la gestion d’une crise environnementale : le naufrage du chimiquier « Ievoli Sun » en Centre Manche

Dans la matinee du 31 octobre 2000 le chimiquier italien « Ievoli Sun » sombrait en Centre Manche. Sa cargaison, presentait un risque de contamination de l’environnement maritime comme de l’environnement littoral situe a proximite. L’Ifremer decidait, des l’annonce du naufrage, de mettre en oeuvre des outils de production et de communication de l’information environnementale. Cette communication presente les solutions adoptees qui ont consiste a elaborer : - un Systeme d’Information Geographique permettant la preparation de cartes, - un ensemble de simulations de la dispersion en mer des produits dissous, - la structure d’un site web de communication generale de l’information (cf. http://www.ifremer.fr/envlit/surveillance/ievoli.htm). Au-dela des presentations techniques des methodes, des outils et des resultats obtenus, ce papier donne une analyse critique du contenu du site et de la forme des produits delivres. En conclusion on discute des perspectives d’evolution scientifique et technique facilitant la communication efficace de donnees environnementales en cas de crises consecutives a des accidents maritimes.