Situation de la pêche aux petits métiers après l'ouverture du nouveau chenal dans la lagune de Nador

Artisanal fishing is the main socioeconomic activity in Nador lagoon, located on the Mediterranean coast in the North East of Morocco. This activity is not part of the official circuit. In 2009, after the deterioration of water quality, public authorities have decided to open an artificial channel with the aim of improving the circulation of water in the lagoon. This work aims to be an update of the state of knowledge of artisanal fishing in the Nador lagoon, after the opening of the new channel, through a diagnosis based on the exploitation and analysis of socioeconomic indicators. The analysis shows that fishermen operate with six jobs. The annual fishing effort is estimated at 72,385 fishing trips. The overall catch is estimated at 1,157 tons annually for a raw product of 28,180,146 MAD. The economic analysis shows that invested capital is 20,723,000 MAD. For a number of 15.4 fishing trips per month, the monthly net profit per boat is 2,465 MAD. The added value produced by all boats is about 6.3 million MAD. Keywords: Nador Lagoon, Diagnosis, Socioeconomic indicators, Artisanal fishing.La pêche artisanale constitue la principale activité socio-économique au niveau de la lagune de Nador. C’est une activité qui sort du circuit officiel. En 2009, suite à la détérioration de la qualité de l’eau, les pouvoirs publics ont décidé l’ouverture d’un chenal artificiel, dans l’objectif de l’amélioration de la circulation de l’eau au niveau de la lagune. Le présent travail propose une actualisation de l’état des connaissances de l’activité de pêche artisanale dans la lagune de Nador, après l’ouverture du nouveau chenal, à travers un diagnostic basé sur l’exploitation et l’analyse d’indicateurs socio-économiques. L’analyse montre que les pêcheurs pratiquent six métiers. L’effort de pêche annuel est estimé à 72.385 sorties. Le volume des captures est estimé à 1.157 tonnes pour un produit brut de 28.180.146 MAD. L’analyse économique montre que le capital investi est de 20.723.000 MAD. Pour un nombre de sorties de pêche de 15,4 /mois, le profit net mensuel par barque est de 2.465 MAD. La valeur ajoutée produite par l’ensemble des unités est d’environ 6,3 millions MAD. Mots clés : Lagune de Nador, Diagnostic, Indicateurs socioéconomiques, Pêche artisanal

Evolution Temporelle Et Spatiale De La Macroflore Benthique De L’ecosysteme Lagunaire De Nador

The objective of the present study undertaken in 2011is to evaluate the status of the benthic macroflora of the Nador lagoon after the management works carried out in 2009 to improve the lagoon environmental quality. Relying on a previous study carried out in 1987, the results of analysis in 2011 showed that the lagoon seabed macroflora recorded a marked decline and an overall change in its distribution and specific composition. The marine Phanerogams, represented by Cymodocea and Zostera, in association with Caulerpa, which were the main vegetationin 1987, were replaced by a macroflora highly dominated by macroalgae (64.3% of the total area), essentially represented by Rhodophyceae (58% of total area).In 2011, the genus Alsidiumwas the main representative in the macroflora(55% of total area),while the genus Caulerpa, and Phanerogamssaw their area of occurrence regress to 25.6% and 18% respectively

Situation de la pêche aux petits métiers après l'ouverture du nouveau chenal dans la lagune de Nador

Artisanal fishing is the main socioeconomic activity in Nador lagoon, located on the Mediterranean coast in the North East of Morocco. This activity is not part of the official circuit. In 2009, after the deterioration of water quality, public authorities have decided to open an artificial channel with the aim of improving the circulation of water in the lagoon. This work aims to be an update of the state of knowledge of artisanal fishing in the Nador lagoon, after the opening of the new channel, through a diagnosis based on the exploitation and analysis of socioeconomic indicators. The analysis shows that fishermen operate with six jobs. The annual fishing effort is estimated at 72,385 fishing trips. The overall catch is estimated at 1,157 tons annually for a raw product of 28,180,146 MAD. The economic analysis shows that invested capital is 20,723,000 MAD. For a number of 15.4 fishing trips per month, the monthly net profit per boat is 2,465 MAD. The added value produced by all boats is about 6.3 million MAD

Caractérisation spatio-temporelle de la production primaire dans la côte Nord-Ouest Africaine par imageries satellitaires MODISA

Une série de quatorze-ans d’images de la couleur de l’océan du capteur MODIS Aqua (MODISA) de 2002 à 2015 a été utilisée pour caractériser la variabilité spatiale et temporelle de la production primaire (PP), à l’échelle saisonnière et interannuelle le long de la côte Nord-Ouest Africaine (entre 15°N et 36°N). Les données de la couleur de l’océan sont mises en œuvre par des modèles mathématiques en faisant une intercomparaison entre leurs produits. La dynamique de la PP est interprétée par la variabilité de la concentration en chlorophylle, la lumière disponible ainsi que celle de l’indice d’upwelling côtier (IUC). On a identifié cinq régions, chacune avec un comportement différent: la région entre 32°N et 36°N caractérisée par une forte saisonnalité de la production et de l’upwelling. La zone entre 28°N et 32°N marque une productivité élevée comparée à la première zone qui s’accompagne par une présence de filaments riches en chlorophylle près du Cap Ghir (31°N) et Cap Juby (28°N). La bande entre 25°N et 28°N présente une activité ascendante de la PP soutenue par l’aspect permanent de l’activité d’upwelling. Entre 21°N et 25°N, cette zone est très perturbée, avec une production intense de part et d’autre du Cap Blanc (21°N). Enfin, la zone au sud de 21°N, la PP est majoritairement abondante en hiver qui coïncide avec la saison d’upwelling dans cette zone. Le modèle qui a été envisagé comme le plus adéquat pour la zone d’étude est VGPM de Behrenfeld et Falkowski (1997) avec intégration du coefficient d’atténuation diffuse Kd490. Le modèle VGPM (Kd) corrigé montre une relation plus affinée avec l’IUC, mais à une échelle plus petite, le modèle de production change en fonction de la zone d’upwelling. A une échelle interannuelle, les différents modèles affichent un pattern d’évolution temporelle similaire mais avec des différences saisonnières et spatiales notables. Mots clés: Production primaire, Côte Nord-Ouest Africaine, Modèles mathématiques, Variabilité saisonnière et interannuelle, MODIS Aqua, Indice d’Upwelling Côtier.  Fourteen years of MODIS Aqua (MODISA) ocean color data are used to characterize the spatial and temporal variability of primary production from 2002 to 2015 in seasonal and interannual timescales along the northwest African coast (between 15°N and 36°N). The ocean color data are implemented into mathematical models in order to compare between their different products. Five regions with different behaviors are identified: the area between 32°N-36°N is characterized by a strong seasonality of productivity and upwelling activity. The region between 28°N and 32°N with high productivity in comparison with the first zone accompanied by presence of chlorophyll filaments in coastal zone near Cape Ghir (31°N) and Cape Juby (28°N). The area between 25°N and 28°N shows an ascending primary production activity supported by the permanent aspect of the activity of upwelling in this area. Then, the area between 21°N-25°N, which is disturbed, is characterized by intense production in Cap Blanc (21°N). Finally, the area south of 21°N, where we notice that primary production is mostly abundant in winter season coinciding with the upwelling activity (November to April). VGPM by Behrenfeld and Falkowski in 1997 with backscattering coefficient Kd490, seems to be the most appropriate model for our region of interest. This dynamic is interpreted in regards of remotely sensed chlorophyll, radiation, and coastal upwelling index. Several attempts to correlate between in-situ measurements and satellite observations have been conducted to output a corrected equation that allows us to establish a regional model. Corrected VGPM (Kd) Model indicate a more refined relation with CUI, but on smaller scale, the suitable production model change according to upwelling zone. At interannual timescale, the models show a similar pattern of temporal evolution but with significant seasonal and spatial differences. The dynamics of biomass and primary production study and its relationship with the CUI provides an interesting framework for future studies in NWA region.  Keywords: Primary production, Remote sensing, North-West Africa (NWA), Modeling, seasonal and interannual variability, Upwelling, MODIS-Aqua, CUI

Characterization of the New Status of Nador Lagoon (Morocco) after the Implementation of the Management Plan

The present study was carried out in 2011 with the aims of (1) evaluating the changes in sedimentary distribution that occurred in Nador lagoon seabed (Morocco) after the implementation of the lagoon management plan in 2009; and (2) characterizing its new sedimentary status in 2011. Due to the lack of a baseline, we used the 1992 sedimentary status for comparison. The seabed surface sediment distribution showed a great change between 1992 and 2011. We found the same four sediment facies, which were present in 1992, namely: mud, sandy mud, muddy sand, and fine sand. However, in 2011, mud covered more than 54% of the lagoon seabed surface, mostly located in the middle part of the seabed, whereas in 1992, more than 80% of the lagoon seabed was covered by sandy mud. The sediments’ characteristics showed moderately to poorly sorted facies (S0), ranging between platykurtic and leptokurtic (SK) and with various symmetry indices (SG). The organic matter content in sediment has strongly decreased, from values higher than 20% in most areas in 1992 to a mean value of 3.9% in 2011, ranging from 0.2% to 10.4%, thus confirming that the management actions implemented in 2009 were likely effective in reducing the organic pollution