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Koeck B.,CNRS Training and Research Center on Mediterranean Environments | Pastor J.,CNRS Ecology of Marine Ecosystems and Responses to Stress Laboratory | Larenie L.,CNRS Training and Research Center on Mediterranean Environments | Astruch P.,GIS Posidonie | And 3 more authors.
Brazilian Journal of Oceanography | Year: 2011

In a general context of fisheries decline due to overfishing and to other phenomena such as climate change, it appears to be crucial to implement a sustainable management of natural resources by finding a balance between conservation and exploitation purposes. Artificial reefs (ARs) have recently become one of the existing management tools, often in combination with fishing quotas or marine protected areas. To evaluate the effectiveness of the studied ARs, different methods have been used: (i) visual census by SCUBA diving (AR scale), (ii) fisheries landings survey (local scale) and (iii) external fish tagging (regional scale). Underwater visual census (UVC) showed a significantly higher species richness and density in ARs than in the control site. Abundance, biomass and LPUE data (Landings Per Unit Effort) issued from artisanal fisheries landings survey were not significantly different around the AR system from other fishing grounds of the French Catalan coast. The tagging experiments on Diplodus sargus suggested that the connectivity of demersal fish populations must be taken into account to evaluate the influence area of ARs and thus their indirect impacts on artisanal fisheries. The present study highlights the interest of combining methods covering different spatial scales in order to evaluate direct and indirect impacts of ARs on artisanal fisheries. Methods for the evaluation of AR efficiency are discussed. Source


Bellier E.,French National Institute for Agricultural Research | Bellier E.,Aix - Marseille University | Neubauer P.,Rutgers University | Monestiez P.,French National Institute for Agricultural Research | And 4 more authors.
Ecological Informatics | Year: 2013

The functional form of spillover, measured as a gradient of abundance of fish, may provide insight about processes that control the spatial distribution of fish inside and outside the MPA. In this study, we aimed to infer on spillover mechanism of Diplodus spp. (family Sparidae) from a Mediterranean MPA (Carry-le-Rouet, France) from visual censuses and artisanal fisheries data. From the existing literature, three potential functional forms of spillover such as a linear gradient, an exponential gradient and a logistic gradient are defined. Each functional form is included in a spatial generalized linear mixed model allowing accounting for spatial autocorrelation of data. We select between the different forms of gradients by using a Bayesian model selection procedure. In a first step, the functional form of the spillover for visual census and artisanal fishing data is assessed separately. For both sets of data, our model selection favoured the negative exponential model, evidencing a decrease of the spatial abundance of fish vanishing around 1000. m from the MPA border. We combined both datasets in a joint model by including an observability parameter. This parameter captures how the different sources of data quantify the underlying spatial distribution of the harvested species. This enabled us to demonstrate that the different sampling methods do not affect the estimation of the underlying spatial distribution of Diplodus spp. inside and outside the MPA. We show that data from different sources can be pooled through spatial generalized linear mixed model. Our findings allow to better understand the underlying mechanisms that control spillover of fish from MPA. © 2013 Elsevier B.V. Source


Hestetun J.T.,University of Bergen | Fourt M.,GIS Posidonie | Vacelet J.,French National Center for Scientific Research | Boury-Esnault N.,French National Center for Scientific Research | Rapp H.T.,University of Bergen
Journal of the Marine Biological Association of the United Kingdom | Year: 2015

The study presents Cladorhizidae collected during Ifremer cruises in the Atlantic Ocean from 1981 to 2004. Fifteen species are described from the genera Abyssocladia, Asbestopluma, Chondrocladia and Cladorhiza, with complete descriptions of five new species. While a couple of species were collected at 670-1010 m depth at the Rockall Bank, most species were collected at middle to lower bathyal and abyssal depths (~2000-5000 m), ranging from the northern Atlantic to the Mid-Atlantic Ridge and the coast of Africa at Gabon-Congo. A biogeographic analysis of currently known Arctic, Atlantic and some Antarctic species shows that the majority of included cladorhizids are described from the north-east Atlantic and Arctic Oceans while a lower number of species are known from other parts of the Atlantic Ocean. Large regions are poorly investigated, and previously undescribed species can be expected when sampling in these areas. A regional mostly endemic cladorhizid fauna is predicted for shelf and upper slope areas. Species in the lower bathyal and abyssal seem on the other hand to have a wider geographical distribution. Copyright © Marine Biological Association of the United Kingdom 2013. Source


Morat F.,French National Center for Scientific Research | Mante A.,Conservatoire Etudes des Ecosystemes de Provence Alpes du Sud | Drunat E.,Conservatoire Etudes des Ecosystemes de Provence Alpes du Sud | Dabat J.,Conservatoire Etudes des Ecosystemes de Provence Alpes du Sud | And 3 more authors.
Vie et Milieu | Year: 2011

Despite the interest of studying animal populations at the limit of their geographical distribution, little is known about the shag (Phalacrocorax aristotelis) in the extreme southern part of its range. In this study, the diet of the Mediterranean shag subspecies (P. a. desmarestii) was studied in the Riou Archipelago (French Mediterranean coast) through the analysis of 109 regurgitation pellets during the non-breeding period from 2004 to 2007. The objectives were (i) to determine the diet of the shag in this area, and (ii) to evaluate the interaction with local fisheries. A total of 2462 pairs of otoliths was found in pellets. Six fish families (Atherinidae, Pomacentridae, Labridae, Centracanthidae, Sparidae and Serranidae) composed 92 % of the shag diet (prey number). Shags mainly fish on shallow rocky bottoms and above or in Posidonia oceanica seagrass meadows. As they mainly targeted small fishes (-10 cm TL), they did not strongly overlap with local fishing activities. Moreover, shags and fishermen do not target the same fish species, and commercial prey items represented only 11 % of the total prey in shags diet. Source

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