Institute Mauritanien Of Recherches Oceanographiques Et Des Peches Imrop

Nouâdhibou, Mauritania

Institute Mauritanien Of Recherches Oceanographiques Et Des Peches Imrop

Nouâdhibou, Mauritania
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Bacha M.,University of the Littoral Opal Coast | Jeyid A.M.,University of the Littoral Opal Coast | Jeyid A.M.,Institute Mauritanien Of Recherches Oceanographiques Et Des Peches Imrop | Jaafour S.,University of the Littoral Opal Coast | And 5 more authors.
Journal of Fish Biology | Year: 2016

This study examines the geographic variability in otolith shape of round sardinella Sardinella aurita as a tool for stock discrimination. Fish were analysed from six sampling locations from Senegal to the Mediterranean coast of Morocco. A combination of otolith shape indices and elliptic Fourier descriptors was investigated by multivariate statistical procedures. Within the studied area, three distinct groups were identified with an overall correct classification of 78%. Group A: Nador (Alboran Sea), group B: Casablanca (northern Morocco) and group C: Senegalese–Mauritanian. The results of this study confirm the absence of an Atlantic Ocean–Mediterranean Sea transition for this species, the Gibraltar Strait acting as an efficient barrier for S. aurita population separation. Off north-west Africa, fish from northern Morocco form a single group which is clearly isolated from Senegalese–Mauritanian waters, confirming the existence of a distinct stock in this area. Among group C, some discontinuity exists and suggests the existence of a sedentary fraction of S. aurita in northern Mauritania (Arguin Bank). The results are discussed in relation to oceanographic features and physical barriers to dispersal and fish management strategy in the study area. © 2016 The Fisheries Society of the British Isles

Braham C.-B.,Institute Mauritanien Of Recherches Oceanographiques Et Des Peches Imrop | Braham C.-B.,IRD Montpellier | Freon P.,IRD Montpellier | Laurec A.,Population Dynamics and Modelling | And 2 more authors.
Fisheries Research | Year: 2014

Sardinella spp. are the main species fished in Mauritanian waters. Logbook data (1991-2009) were used to standardise CPUE. This clearly revealed that the abundance of sardinella peaked in the warm season (July-September) which is the main, if not the only significant spawning season for round sardinella. This study does not directly confirm or falsify the common belief that the adults migrate from the Senegalese EEZ up to north of the 21°. N latitude, but it presents a variety of new hypotheses. If a single transboundary stock exists, part of its individuals, or a sub-stock, is probably more sedentary and remains in the permanent upwelling area located in northern Mauritania and southern Morocco. Between years, changes in abundance index are dominated by a decrease from 1996 to 2006, depending on the months taken into account, and especially whether or not the warm (spawning) season is considered. For a given month, the spatial distribution of sardinella shows limited differences between years. In the southernmost latitudes of the Mauritanian EEZ the seasonal pattern, which is dominated by high catch rates during the warm season, is much stronger after the year 2001, and then tended to increase year after year. Changes in species distribution and abundance during the twenty-year study period are difficult to relate to environmental dynamics. However, an inversion of the upwelling trend was observed in 2001, matching a change in the seasonality of sardinella catches, although the causality between the two phenomena could not be established. The increase in the abundance index of sardinella in the last five years, particularly during most of the core fishing season (July-September) might be due to favourable oceanographic conditions (higher upwelling index) and/or changes in the fishing strategies or efficiency. Before annual indices of abundance can be used in the future, it will be necessary to better understand possible changes in catchability during the warm/spawning season. © 2014 Elsevier B.V.

Bez N.,IRD Montpellier | Braham C.-B.,Institute Mauritanien Of Recherches Oceanographiques Et Des Peches Imrop
Canadian Journal of Fisheries and Aquatic Sciences | Year: 2014

In North West Africa, pelagic fisheries are an essential economic sector. However, the scientific community fails to perform satisfactory assessments of key pelagic species like sardinella, owing to a lack of relevant indices of abundance to tune the model. This paper provides an alternative acoustic index based on a semiquantitative modelisation of acoustic densities. Acoustic energy is split into binomial variables coding for null, low, medium, large, and very large densities. A multivariate geostatistical approach allows (i) mapping the spatial distribution of classes of densities and (ii) computing a new acoustic index of abundance for Sardinella aurita and Sardinella maderensis.We used the surveys of RV Fridtjof Nansen (1995-2006) and RV Al-Awam (2007-2010). Our results indicated that empirical spatial structures were highly stable over time for both between areas and surveys. Co-kriging maps also showed that sardinella had stable hot spots of distribution. The indices of abundance developed in the present study were tested in an assessment procedure and outperformed all the indices used routinely by the FAO-CECAF (Fishery Committee for the Eastern Central Atlantic) assessment working group.

Beibou E.,Institute Mauritanien Of Recherches Oceanographiques Et Des Peches Imrop | Beibou E.,IRD Montpellier | Guitton J.,Agrocampus Ouest | Barde J.,IRD Montpellier
Ingenierie des Systemes d'Information | Year: 2015

Research institutions are always struggling to adopt an effective system to manage their information assets. The effective management of various sources of information in fact depends on the integration and interoperability of information systems partners. The sources are always complementary, because they cover different themes. But, taken separately, they often provide a fragmented vision for a scientific question, hence the importance of their integration. Similarly, knowledge and expertise of the users of these various sources and actors in the field must be taken into account and integrated into the system, hence the importance of a collaborative tool. We will relate in this article how the SCIP at IMROP overcomes these difficulties by proposing an innovative approach based on mediation and collaboration. © 2015 Lavoisier.

Jung J.-L.,University of Western Brittany | Mullie W.C.,Programme Biodiversite | Van Waerebeek K.,Peruvian Center for Cetacean Research | Van Waerebeek K.,Cheikh Anta Diop University | And 6 more authors.
Marine Biology Research | Year: 2016

The surveillance of marine mammal strandings within the framework of a biomonitoring scheme for the Mauritanian coast led to the discovery in 2013 of a 3.98 m long, juvenile rorqual Balaenoptera sp. in an advanced state of decomposition near Chott Boul (16°32.488′N, 016°27.0317′W). Photographs and skin samples were taken, but the specimen could not be collected. Based on limited morphological evidence, only Balaenoptera edeni and B. omurai were plausible. Sequences of three mtDNA regions, i.e. parts of the cox1 and the cytb genes as well as the D-loop, for a total of 2636 bp (> 16% of the mitogenome) identified the specimen as an Omura’s whale, B. omurai, the first record in the Atlantic Ocean and at least 11,400 km away from its closest known range in the SW Indian Ocean (Madagascar). The question of whether the specimen is a vagrant or belongs to an unrecognized Atlantic population is discussed. Advection by currents or transport on a ship’s bow bulb following collision are discarded. Circumstances (juvenile status, great distance from Indo-Pacific, necessary inter-oceanic passage through cold temperate waters) may slightly favour the hypothesis that B. omurai, if rare, could be autochthonous in the Atlantic. Beach surveys remain a useful tool to assess trends in cetacean species composition, to detect unusual mortality events and to help assess the impacts of anthropogenic activities. This is particularly applicable to remote areas where the marine mammal fauna is poorly known and where fisheries effort is high, such as the Mauritanian coast. © 2015 Taylor & Francis.

Guenette S.,Agrocampus Ouest | Meissa B.,Agrocampus Ouest | Meissa B.,Institute Mauritanien Of Recherches Oceanographiques Et Des Peches Imrop | Gascuel D.,Agrocampus Ouest
PLoS ONE | Year: 2014

Most modelling studies addressed the effectiveness of marine protected areas (MPA) for fisheries sustainability through single species approach. Only a few models analysed the potential benefits of MPAs at the ecosystem level, estimating the potential export of fish biomass from the reserve or analysing the trophic relationships between organisms inside and outside the MPA. Here, we propose to use food web models to assess the contribution of a MPA to the trophic functioning of a larger ecosystem. This approach is applied to the Banc d'Arguin National Park, a large MPA located on the Mauritanian shelf. The ecosystem was modeled using Ecopath with Ecosim, a model that accounts for fisheries, food web structure, and some aspects of the spatial distribution of species, for the period 1991'2006. Gaps in knowledge and uncertainty were taken into account by building three different models. Results showed that the Banc d'Arguin contributes about 9 to 13% to the total consumption, is supporting about 23% of the total production and 18% of the total catch of the Mauritanian shelf ecosystem, and up to 50% for coastal fish. Of the 29 exploited groups, 15 depend on the Banc for more than 30% of their direct or indirect consumptions. Between 1991 and 2006, the fishing pressure increased leading to a decrease in biomass and the catch of high trophic levels, confirming their overall overexploitation. Ecosim simulations showed that adding a new fleet in the Banc d'Arguin would have large impacts on the species with a high reliance on the Banc for food, resulting in a 23% decrease in the current outside MPA catches. We conclude on the usefulness of food web models to assess MPAs contribution to larger ecosystem functioning. © 2014 Guénette et al.

Meissa B.,Institute Mauritanien Of Recherches Oceanographiques Et Des Peches Imrop | Meissa B.,European University of Brittany | Gascuel D.,European University of Brittany
ICES Journal of Marine Science | Year: 2014

The recent, rapid development of fishing in Mauritania offers a good case study for a comparative approach of the resilience of the species exploited there, in the face of increasing fishing pressure. First, we assessed the health of 22 demersal stocks with differing ecological requirements, demographic strategies, and states of exploitation. A dynamic production model was fitted in a framework of Bayesian statistics to abundance indices estimated from scientific trawl surveys or commercial catch per unit efforts. We show that 12 of the 22 stocks assessed are overexploited and 3 are fully exploited. The combined assessment of all 22 stocks demonstrates an overall overexploitation, with total demersal biomass decreasing by ∼75% since 1982 and fishing effort 30% higher than that at maximum sustained yield (40% higher for finfish). Second, relations between states of stocks and life history traits were analysed. The stocks of large and vulnerable species currently undergo the highest fishing pressure and are those that are the most overexploited. At the scale of the community represented by the stocks considered, surveys-based indictors of the mean intrinsic vulnerability, the mean maximum length, and the mean trophic level exhibit a significant decrease from 1990 to 2010. Changes observed in catch-based indicators depend on fishing strategies and are impacted by the recent development of the small-scale fishery. But indicators expressed as a function of a multiplier of fishing effort or fishing mortality clearly decrease, thus confirming that the intensification of exploitation leads to communities dominated by smaller species and lower trophic levels. We conclude that large and high trophic level species, such as white grouper, meagre, guitarfish, and smooth-hound, are markers of ecosystem health and should be considered as sentinel species. © 2014 International Council for the Exploration of the Sea.

Meissa B.,Institute Mauritanien Of Recherches Oceanographiques Et Des Peches Imrop | Meissa B.,Agrocampus Ouest | Gascuel D.,Agrocampus Ouest | Rivot E.,Agrocampus Ouest
African Journal of Marine Science | Year: 2013

The lack of reliable stock assessment for numerous exploited stocks in West Africa often results from poor-quality data, high multi-specificity of captures, and the heterogeneity of exploitation methods. However, many signs of overexploitation exist, particularly for demersal resources, highlighting the urgent need for a more quantitative and comprehensive evaluation of these resources. This study aims to show how, in such a context of poor-quality data and high uncertainty, a multi-method approach for stock assessment can generate a consistent diagnosis of the condition of a resource. As a case study, several methods were combined to assess the stock status of the white grouper Epinephelus aeneus, a flagship species in West Africa that is exploited by industrial and small-scale fisheries in Mauritania. These were estimation of abundance indices using delta generalised linear models; a biomass production model using a pseudo-equilibrium method and including an environmental effect of upwelling intensity; a dynamic biomass production model fitted in a Bayesian framework also including an environmental effect; and an age-structured model based on a modified pseudo-cohort analysis. Sensitivity analyses were performed for most of these assessment methods. Results show that the white grouper stock is highly overexploited due to an excess in the fishing effort estimated at between 30% and 50%, depending on the model used to estimate the effort at maximum sustainable yield. © 2013 Copyright NISC (Pty) Ltd.

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