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Morat, F., Letourneur, Y., Blamart, D., Pecheyran, C., Darnaude, A. M., & Harmelin-Vivien, M. (2014). Offshore-onshore linkages in the larval life history of sole in the Gulf of Lions (NW-Mediterranean). Estuarine Coastal and Shelf Science, 149, 194–202.
Résumé: Understanding individual dispersion from offshore natal areas to coastal nurseries during pelagic larval life is especially important for the sustainable management of exploited marine fish species. For several years, the hatching period, the larval life duration, the average growth rate and the otolith chemical composition (delta C-13, delta O-18, Sr:Ca and Ba:Ca) during the larval life were studied for young of the year (YOY) of sole collected in three main nurseries of the Gulf of Lions (GoL) (Thau, Mauguio and Berre). We investigated the spatial variation in the origin of the sole larvae which colonised the nurseries around the GoL, and whether temporal differences in environmental conditions during this life stage affected growth and larval life duration. The hatching period ranges from October to March, depending on year and site. Average ages at metamorphosis varied between 43 and 50 days, with the lowest and highest values consistently found for Mauguio and Berre, respectively. Otolith growth rates ranged between 2.7 and 3.2 mu m d(-1), with the lowest values in Thau and Mauguio and the highest in Berre. Otolith chemical composition during the larval life also varied, suggesting contrasted larval environmental histories in YOY among nurseries. In fishes from Berre and Mauguio, larval life was more influenced by the Rhone River, showing consistently higher larval Ba:Ca ratios (10/23 mu mol mol(-1)) and lower delta C-13 (-6.5/-6.1 parts per thousand) and delta O-18 values (-1.6/0.1 parts per thousand) than for Thau (with Ba:Ca ratios < 8 mu mol mol(-1), delta C-13 similar to-2.3 parts per thousand and delta O-18 similar to 1.5 parts per thousand). Differences in larval otolith composition were observed for 2004, with higher Ba:Ca and lower delta C-13 and delta O-18 values than in the two other years. These differences were explained by changes in composition and chemical signatures of water masses after an exceptional flooding event of the Rhone River in late 2003. (C) 2014 Elsevier Ltd. All rights reserved.
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Potier, M., Bach, P., Ménard, F., & Marsac, F. (2014). Influence of mesoscale features on micronekton and large pelagic fish communities in the Mozambique Channel. Deep-Sea Research Part II.Topical Studies in Oceanography, 100(No spécial), 184–199.
Résumé: We investigated the diversity and distribution of two communities, micronekton organisms and large predatory fishes, sampled in mesoscale features of the Mozambique Channel from 2003 to 2009, by combining mid-water trawls, stomach contents of fish predators and instrumented longline fishing surveys. The highest species richness for assemblages was found in divergences and fronts rather than in the core of eddies. Despite an unbalanced scheme, diversity indices did not differ significantly between cyclonic and anticyclonic eddies, divergences and fronts. We found that eddies and associated physical cues did not substantially affect the distribution of micronektonic species which are mainly driven by the diel vertical migration pattern. Top predators exhibited a more complex response. Swordfish (Xiphias gladius) associated better with mesoscale features than tunas, with a clear preference for divergences which is consistent with the diel vertical migrations and occurrence of its main prey, the flying squids Sthenoteuthis oualaniensis (Ommastrephidae). On the other hand, the probability of presence of yellowfin tuna was not tied to any specific eddy structure. However, the highest values of positive yellowfin CPUEs were associated with low horizontal gradients of sea-level anomalies. We also showed a non-linear response of positive yellowfin CPUEs with respect to the depth of the minimal oxygen content. The larger the distance between the hooks and the minimal oxygen layer, towards the surface or at greater depths, the higher the CPUE, highlighting that yellowfin congregated in well-oxygenated waters. Micronekton sampled by mid-water trawls and stomach contents exhibited different species composition. The highly mobile organisms were not caught by trawling whereas they remain accessible to predators. The combination of stomach contents and mid-water trawls undoubtedly improved our understanding of the micronekton assemblage distribution. Our results provide some evidence that mesoscale features in the Mozambique Channel do not strongly affect the distribution of the mid-trophic level organisms such as micronekton and most of the large predatory fishes, and hypotheses are proposed to support this result.
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Coll, M., Carreras, M., Cornax, M. J., Massuti, E., Morote, E., Pastor, X., et al. (2014). Closer to reality : reconstructing total removals in mixed fisheries from Southern Europe. Fisheries Research, 154, 179–194.
Résumé: Underestimation of catches is especially important in countries where fishing fleets are highly diversified, the enforcement of fishery management is low, data availability is poor, and there is high demand for fish products in local markets. This is the case for southern European and Mediterranean regions. Adapting a catch-reconstruction approach, we estimated the total removals of marine resources by Spain for the Spanish Mediterranean Sea and Gulf of Cadiz regions from 1950 to 2010. We collected available information from scientific publications, the grey literature and secondary sources of information to complement officially reported catch data. We assessed missing catch sectors as time-point estimates, used as anchor points of reliable data upon which we then estimated total catch using interpolation to fill in the periods for which quantitative data were missing. Unreported removals and discards represented important portions of total removals in the study area. They accounted for, on average, 43% of total removals between 1950s and 2010, and were composed of black market sales, subsistence fishing, artisanal fishing, recreational fishing and illegal catch, in addition to discarding. By the late 2000s, recreational fishing was the most important sector for unreported landings (similar to 36%), followed by black market sales (similar to 32%), subsistence fishing (similar to 17%), unreported artisanal fishing (similar to 12%) and illegal catch (similar to 2%). The overall catch trend differed from the official trend highlighting that the depletion of marine resources in the region started earlier than previously observed. The catch composition changed with time, with a higher diversification of species in fish markets with time. These results indicate an earlier trend towards expansion of fisheries and depletion of marine resources.
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BROGGIATO, A., ARNAUD-HAOND, S., CHIAROLLA, C., & GREIBER, T. (2014). Fair and equitable sharing of benefits from the utilization of marine genetic resources in areas beyond national jurisdiction: Bridging the gaps between science and policy. Marine Policy, 49, 176–185.
Résumé: Marine genetic resources are a subject of a growing body of research and development activities, as demonstrated by the abundance of marine patented genes reported in GenBank. Given the lack of a comprehensive legal regime for the management of marine genetic resources in areas beyond national jurisdiction, the General Assembly of the United Nations met in 2006 to discuss whether there are regulatory or governance gaps and how to address them. Besides the crystallization of the different political positions, the process is now advancing towards making a decision about whether to develop an international instrument under the United Nations Convention on the Law of the Sea (UNCLOS) for the conservation and sustainable use of marine biological diversity, within which the regulation of access to genetic resources and the sharing of benefits from their utilization has emerged as an in-dissociable issue. In order to propose concrete options to be considered for the establishment of a legal framework addressing these issues, policy-makers need to better understand the feasibility, the costs and the modalities of scientific activities undertaken, together with the actual level of commercialization of new products. They also need to be aware of the already advanced practices in place within the scientific community, especially regarding sharing of non-monetary benefits. This paper particularly highlights and discusses practical scenarios to advance in the international process, based on the approaches adopted in other regional and international regimes for the management of genetic resources and on the best practices developed within the scientific community.
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Triki, H. Z., Daly-Yahia, O. K., Malouche, D., Komiha, Y., Deidun, A., Brahim, M., et al. (2014). Distribution of resting cysts of the potentially toxic dinoflagellate Alexandrium pseudogonyaulax in recently-deposited sediment within Bizerte Lagoon (Mediterranean coast, Tunisia). Marine Pollution Bulletin, 84(1-2), 172–181.
Résumé: This study investigated the spatial distribution of Alexandrium pseudogonyaulax resting cysts in recently-deposited sediment of Bizerte lagoon (South-Western Mediterranean, Tunisia). This lagoon is the subject of many anthropogenic impacts, such as holding important fishing and aquaculture activities. A. pseudogonyaulax has been shown to produce Goniodomin A, which is a biologically-active compound. We showed that this dinoflagellate produces two types of resting cysts, which could be distinguished by the presence or the absence of a paratabulate wall. The average cyst density across the whole lagoon was rather high, reaching 639 cysts g(-1) of dry sediment (DS). Cyst densities varied widely among the sampled stations, with the highest density of 1685 cyst g(-1) DS being recorded at station 51 near a mussel farm. With respect to sediment characteristics, the highest cyst densities were found within silty sediments with high water content values. The distribution of A. pseudongoyaulax cysts in Bizerte lagoon appears to be related to hydrodynamic factors. (C) 2014 Elsevier Ltd. All rights reserved.
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