Diversité Biologique Et Structure De La Faune Ichtyologique De l’Aire Marine Protégée De Joal-Fadiouth Au Sénégal

Cette étude vise à mieux faire connaître le fonctionnement écologique de l’aire marine protégée (AMP) de Joal-Fadiouth via l’inventaire de sa composition spécifique et la répartition spatiale de sa faune ichtyologique. A cet effet, un suivi bioécologique a été mené durant les 4 saisons hydrologiques de 2015 à 2017, au niveau de 6 stations caractéristiques des habitats de l’AMP, avec les mêmes engins et équipe de pêcheurs. Les analyses statistiques ont été effectuées à l’aide du logiciel XLSTAT 2017. Au bilan, 120 espèces de poissons appartenant à 86 genres et 48 familles ont été identifiées. Les Carangidae sont les plus nombreux avec 13 espèces. Elles sont suivies par les Sparidae (08), les Haemulidae et Mugilidae (07 chacune), les Solidae (06), les Sciaenidae et les Tetraodontidae (05), les Polynemidae et Serranidae (4 chacune), et 6 et 11 autres familles avec respectivement, 3 et 2 espèces. Les 23 autres familles affichent chacune une seule espèce. Seules 2 espèces parmi les 70 jusque-là identifiées par des études antérieures n’ont pas été retrouvées par cette étude qui a permis de revoir cette liste avec 57 nouvelles espèces. Cette richesse spécifique est inégalement répartie dans l’AMP. La station « Kher-ciment » présente la richesse spécifique la plus importante avec 75 espèces, soit 59 % de l’ichtyofaune de l’AMP de Joal-Fadiouth. Elle est suivie de celles du Quai de pêche (70 espèces, 55 %), du Bolong Mbissel et Ngousse Diohé (65 espèces pour chacune, soit 51,18 %), du Bolong Mama Nguedj (64 espèces, 50 %) et de la Zone « tortues » (48 espèces, 38 %). Chacune de ces zones présente une richesse spécifique supérieure au maximum de 52 espèces jusque-là rencontré dans une zone et largement au-delà des 18 espèces d’une station dominante dans l’AMP de Cayar. Avec ces résultats, cette confirme l’importance de ces zones pour le fonctionnement écologique de l’AMP. This study aims to raise awareness of the ecological functioning of the Joal-Fadiouth marine protected area (MPA) through the inventory of its specific composition and the spatial distribution of its ichthyological fauna. To this end, bioecological monitoring was carried out during the 4 hydrological seasons from 2015 to 2017, at 6 stations characteristic of MPA habitats, with the same gear and team of fishermen. The statistical analyzes were performed using the XLSTAT 2017 software. In the balance, 120 species of fishes belonging to 86 genera and 48 families have been identified. The Carangidae are the most numerous with 13 species. They are followed by Sparidae (08), Haemulidae and Mugilidae (07 each), Solidae (06), Sciaenidae and Tetraodontidae (05), Polynemidae and Serranidae (4 each), and 6 and 11 other families with 3 and 2 species respectively. The other 23 families each display a single species. Only 2 of the 70 species so far identified by previous studies were not found by this study, which made it possible to review this list with 57 new species. This specific richness is unevenly distributed in the MPA. The "Kher-cement" station has the highest specific richness with 75 species, or 59% of the ichthyofauna of the Joal-Fadiouth MPA. It is followed by those of the fishing wharf (70 species, 55%), Bolong Mbissel and Ngousse Diohe (65 species for each, or 51.18%), Bolong Mama Nguedj (64 species, 50%) and “Turtles” area (48 species, 38%). Each of these zones has a specific richness greater than the maximum of 52 species hitherto encounted in a station of MPA, and far beyond the 18 species identified in a dominant station in the Cayar MPA. With these results, this study confirm the importance of these zones for the ecological functioning of the MPA

Long-term fishing impact on the Senegalese coastal demersal resources: diagnosing from stock assessment models

For the first time in Senegal, assessments based on both stochastic and deterministic production models were used to draw a global diagnosis of the fishing impact on coastal demersal stocks. Based one national fisheries databases and scientific trawl surveys data: (i) trends in landings since 1971 were examined, (ii) abundance indices of 10 stocks were estimated using linear models fitted to surveys data and commercial catch per unit efforts, and (iii) stock assessments were carried out using pseudo-equilibrium Fox and Pella-Tomlinson models and a Biomass dynamic production model fitted in a Bayesian framework to abundance indices. Most stocks have seen their abundance sharply declining over time. All stocks combined, results of stock assessments suggest a 63% reduction compared to virgin state. Three fifth of demersal stocks are overexploited and excess in fishing effort was estimated until 75% for the worst case. We conclude by suggesting that the fishing of such species must be regulated and an ecosystem approach to fisheries management should be implemented in order to monitor the whole ecosystem

Report on biological and ecological data in FFDB pilot version 1

Task 2.3 of work package 2 (Advancing biological knowledge and evaluation of current stock assessment models) focuses on the compilation of biological, ecological and fisheries dependent and fisheries independent data that is required for other FarFish WPs. During the first year of FarFish, some modifications in the objectives occurred, resulting in changes in the species. For example, in the Cape Verde and Seychelles CSs, the focus is now on by-catch species that are not assessed by the Regional Management Fisheries Organizations (RMFO): the International Commission for the Conservation of Atlantic Tunas (ICCAT) and the Indian Ocean Tuna Commission (IOTC). Lists of species for each CS have now been drawn up, sources of data identified, contacts have been made with RMFOs and DG MARE, and data is being compiled. Data compilation has been largely driven by the FarFish Data Base (FFDB) template developed in WP 6 (see deliverables D6.1 and D6.4). On the other hand, other data required for visualization purposes, especially time series, is also being compiled or requested. A formal data request is being prepared for DG MARE, while coastal state CS participants will be requested to provide data for the FFDB. Talks are also ongoing with RFMOs, especially CECAF, regarding data acquisition and how FarFish can contribute or add value to assessment and management. Actions that need to be taken by Task 2.3 participants include the provision of data and uploading of data to the FFDB. Task 2.3 is ongoing (Report on biological and ecological data in FFDB pilot version 2, due in Month 26 (July 31, 2019)

Les zones de pêche protégées au Sénégal : entre terroir du pêcheur et parcours du poisson. Quelle(s) échelle(s) de gestion ?

The villages of Mballing, Nianing, Point Sarène and Mbodiène located on the « Petite Côte » of Senegal, intended to implement their own Protected Fishing Zone (PFZ). Fishermen define the PFZ according to empirical knowledge on fish biology but also on their means to insure the application of management rules on the PFZ. Surfaces covered do not exceed two kilometers offshore from the coastline. Support researches have shown that the narrowness of zones covered offshore, raised the relevance of the PFZ efficiency on the management of the species demersal targeted. Regarding the case of Petite Côte, the shallow rocky zones (2 to 3 m of depth) extend on 3-4 kilometers offshore. It has been recommended to establish common PFZ that covers at least 3 km offshore to include spawning and nursery area for the main targeted species. However, the scientific argument putting forward the fish area repartition, here in the sense of « path » [parcours], comes up against the community’s identification to their « local area » [terroir]

Les zones de pêche protégées au Sénégal : entre terroir du pêcheur et parcours du poisson. Quelle(s) échelle(s) de gestion ?

The villages of Mballing, Nianing, Point Sarène and Mbodiène located on the « Petite Côte » of Senegal, intended to implement their own Protected Fishing Zone (PFZ). Fishermen define the PFZ according to empirical knowledge on fish biology but also on their means to insure the application of management rules on the PFZ. Surfaces covered do not exceed two kilometers offshore from the coastline. Support researches have shown that the narrowness of zones covered offshore, raised the relevance of the PFZ efficiency on the management of the species demersal targeted. Regarding the case of Petite Côte, the shallow rocky zones (2 to 3 m of depth) extend on 3-4 kilometers offshore. It has been recommended to establish common PFZ that covers at least 3 km offshore to include spawning and nursery area for the main targeted species. However, the scientific argument putting forward the fish area repartition, here in the sense of « path » [parcours], comes up against the community’s identification to their « local area » [terroir]

Long term changes in life history traits and catches of the round sardinella, Sardinella aurita (Clupeidae), along the Senegal coast, West Africa

The main life history traits of the round sardinella, Sardinella aurita Valenciennes 1847 were updated in Senegalese coastal waters, together with an evaluation of the captures over the last 33 years (1981-2013). In the context of global change and an increase in the average sea surface temperature along the Senegalese coast, most of the life history traits of S. aurita, such as condition factor, period of reproduction, egg sizes, relative fecundity and growth did not change significantly over the years. In contrast, the size at first sexual maturity and the absolute fecundity increased significantly, and current catches recorded less large individuals. The growth was rapid and very variable, with a longevity estimated at 6-7 years. These updated data for life history traits show that the round sardinella was fully exploited in the area, that the fishing effort for this species should be reduced, and that the minimum size (120 mm) authorized by the Senegalese fisheries code should be increased (185-200 mm) to maintain stocks along the Senegal coast

Composition, distribution and abundance of zooplankton and ichthyoplankton along the Senegal-Guinea maritime zone (West Africa)

A study of zooplankton and ichthyoplankton was carried out from samples collected along the Senegal-Guinea maritime area on board the Norwegian research vessel 'Dr Fridtjof Nansen' in November 2011. Nineteen groups of zooplankton were identified with a dominance of copepods representing 68.5%. The Copepods included 35 species, where Paracalanus parvus was dominant (21.5%). As to ichthyoplankton, 29 fish families were encountered, and Clupeidae were dominant (35.8%). They were represented by Sardinella spp (98.0%) and by Sardina pilchardus (2.0%). An area of high density of copepods (5250 individuals/m3) was located at the mouth of the Gambia River. Two areas of high densities of fish eggs were identified in the waters off Senegal and Guinea; one was characterized by high surface temperature and salinity (29 °C and 35) and moderately oxygenated (3.8 ml/l), while the other was slightly warm (25.5–27.5 °C), less salty (31.5) and highly oxygenated (4.8 ml/l). Areas of high zooplankton biomass correspond to the zones of high dissolved oxygen concentration (4–4.5 ml/l) of low salinity (31.5–34.5). This pattern is supported by the results of the PCA, through the station PL4. Keywords: Distribution, Ichthyoplankton, Zooplankton, Hydrography, West Afric

Dynamique du Yabóy mërëg et du Cobo au Sénégal dans un contexte de changement climatique : diagnostic et synthèse bioécologique

MESSAGES CLES 1. Améliorer les avis scientifiques nécessaires pour une gestion durable de deux principaux stocks de petits pélagiques côtiers exploités dans la zone sénégalaise (Yabóy mërëg et Cobo)

Dynamique du Yabóy mërëg et du Cobo au Sénégal dans un contexte de changement climatique : diagnostic et synthèse bioécologique

MESSAGES CLES 1. Améliorer les avis scientifiques nécessaires pour une gestion durable de deux principaux stocks de petits pélagiques côtiers exploités dans la zone sénégalaise (Yabóy mërëg et Cobo)

The potential impact of marine protected areas on the Senegalese sardinella fishery

WOS:000459518700024International audienceIn the early 2000s, Senegal set up several Marine Protected Areas (MPAs) along its coastal zone with the purpose of biodiversity conservation and to support sustainable management of fisheries. However, the impact of MPAs may vary according to the type of fisheries. In Senegal, the sardinella fishery accounts for 70% of total catches. This fishery is of crucial importance for national food security and employment. Given this importance, it is necessary to evaluate the impact of MPAs, often being considered as a tool for fisheries management. An analytical, dynamic and spatial bio-economic model of sardinella fishery, considering fish and fisher migration, has been developed and scenarios over forty years have been analyzed. The results show that the fishery is economically overexploited and that Senegal could lose about 11.6 billion CFA over forty years of exploitation, i.e. 290 million CFA per year. To achieve an optimal level of exploitation, it would be necessary to halve the current fishing capacity. Implementing MPAs for 10, 20 and 30% of the Senegalese exclusive economic zone lead to slight increases in biomass (1%) and rent (5-11%). In addition, spatio-temporal closures can lead to increased exploitation in unclosed areas, due to the absence of enforcement. Achieving target 11 of the Aichi Convention, i.e., 10% of coastal and marine areas protected per country, will have a reserve effect on the resource but also only lead to weak improvements in economic indicators for the Senegalese fishery. Finally, because the sardinella resource is shared among many countries of the Sub-Regional Fisheries Commission (SRFC), a sub-regional cooperation is necessary for a sustainable management