Biodiversity and Status of Cetaceans in Benin, West Africa: an Initial Assessment

No published literature is available on the whales and dolphins of Benin. A first insight in the cetacean biodiversity based on stranding, capture and sighting records, as well as a preliminary assessment of status, is provided. Seven species were authenticated: humpback whale Megaptera novaeangliae, common bottlenose dolphin Tursiops truncatus, Atlantic spotted dolphin Stenella frontalis, false killer whale Pseudorca crassidens, shortfinned pilot whale Globicephala macrorhynchus, Cuvier’s beaked whale Ziphius cavirostris and sperm whale Physeter macrocephalus. Two additional taxa were confirmed at genus level, i.e. common dolphin Delphinus sp. and minke whale Balaenoptera sp. All reported species also occur in Ghana or Togo. Concern is expressed that in Benin, as in some other western African nations, coastal communities increasingly exploit stranded and by-caught cetaceans to supply a thriving, albeit illegal, marine bushmeat trade. Small cetaceans were also taken intentionally in the absence of efficient controls of landings or other management measures. Although presently at subsistence scale, the threat of wider commercialization exists. In view of the limited number of validated species, voucher specimens and scarce biological baseline information, opportunistic sampling must be expanded to include more systematic and dedicated research, in particular, ship-based marine mammal surveys. It is recommended that graduate students at Benin’s universities play a central role

OPENMODS 2.0 “Instrument Jamming Meeting” report

Major achievements The feedback provided by potential users on their needs was very much appreciated. They underlined the importance of having: ● an easy to deploy instrument (i.e.: from small fishing boats); ● multi-parameter sensors in ONE device; ● less maintenance effort and prioritized the variables to measure. Although, there are technical limitations and different solutions and there is no one tool that can do everything, which is low cost, has high resolution and low maintenance, the outcomes of the platforms/sensors/communications working group meet the main requirements that emerged. Priority was given to: ● a platform that will operate in drifter mode which is extremely easy to deploy and perfect for studies associated with search and rescue operations (another need that has emerged). It also constantly guarantees the knowledge of the instrument position. The platform can be easily converted into the moored mode. ● temperature and pressure sensors. The sensors will be low -cost with the idea to replace them rather than calibrate them; ● LoRaWAN communications preferably with Bluetooth integration for the in-situ download of the data

Presence de la crevette tigree, Penaeus monodon (fabricius, 1798) (crustacea, penaeidae) dans les eaux maritimes beninoises

Des crevettes géantes tigrées, Penaeus monodon (Fabricius, 1798) ont été capturées dans les eaux béninoises (Golfe de Guinée). Ces captures ont eu lieu sur le plateau continental, aux embouchures et dans les différents plans d'eau intérieurs du Bénin. Elles sont atypiques car P. monodon est seulement citée dans l'océan Indien et le Pacifique. Elles s'expliquent donc par le fait que des spécimens se sont déplacés certainement depuis les stations aquacoles situées au sud du Sénégal et en Gambie. La capturede cette espèce dans les eaux béninoises relève d'un phénomène que nous proposons d'analyser et de discuter après avoir présenté nos observations sur les crevettes géantes tigrées. L'espèce s'est probablement acclimatée depuis quelques années dans la région en dépit d'une possible compétition avec l'espèce autochtone. Farfantepenaeus notialis (Pérez Farfante 1967) qui habite les mêmes biotopes. Un suivi régulier et approfondi des différentes espèces est nécessaire dans un avenir proche

Peche a la senne de plage au Benin et durabilite des ressources halieutiques

La senne de plage est un engin de pêche non sélectif, muni de poche qui, après l’encerclement des aires marines fait l’objet de halage à terre pendant des heures. Elle est généralement utilisée dans des eaux peu profondes à proximité du rivage. Un sondage a été réalisé au niveau des douze campements ciblés pour étudier les espèces régulièrement rencontrées, les périodes de pêche, les espèces en disparition en vue de comparer les rendements actuels avec les tailles des captures à ceux des années antérieures. Au total, 175 acteurs (propriétaires de filets, pêcheurs et mareyeuses) ont été enquêtés. La longueur totale de toutes les espèces  dominantes a été mesurée de façon discontinue de juin 2011 à mars 2013. Les espèces débarquées sont constituées d’une diversité de poissons de tailles variées avec une proportion élevée de juvéniles. Aussi, la senne de plage détruit-elle les habitats des poissons côtiers, les nurseries et les aires de recrutement (Kebe M. et al., 1997, Beurier J. P. et Keïta R., 1982). Les juvéniles  dominantes des captures sont, entre autres, le Musso africain (Selene dorsalis), l’Alose (Ilisha  africana), le Sapater (Chloroscombrus chrysurus), la Sardinelle ronde (Sardinella maderensis), l’Ethmalose d’Afrique (Ethmalosa fimbriata), la Bécume   guachanche (Sphyraena guachancho), l’Otholithe sénégalais (Pseudotolithus senegalensis), le Poisson sabre commun (Trichiurus lepturus), l’Anchois (Engraulis encrasicolus) et la crevette rose (Farfantepenaeus notialis). La pêche massive de juvéniles a conduit inévitablement au ralentissement du recrutement dans le   stock ; ce qui entraine la modification dans le temps de la pyramide des âges avec gonflement des classes jeunes et tassement des classes âgés et la diminution des rendements de pêche. La surexploitation des ressources enferme davantage le pêcheur artisan dans un cercle vicieux de la pauvreté (CRHOB 2004, Hounsounou L. C., 2011).Mots clés : Senne de plage, poissons juvéniles, campements, pêcheurs artisans

Aquaculture marine au Benin : Perspectives de l’elevage de Lutjanus agennes, Epinephelus Aeneus et Mugil cephalus

Des essais d’élevage de Lutjanus agennes, Epinephelus aeneus et Mugil cephalus) ont été réalisés en étangs pendant 12 mois. Une fertilisation naturelle des étangs et une complémentation alimentaire des sujets ont été utilisées. Les paramètres environnementaux (température, salinité de l’eau) et les paramètres  morphométriques de chaque espèce ont été mesurés. Les résultats montrent une croissance pondérale et en longueur significative d’une espèce à l’autre (p < 0,05) au cours de la période de l’essai. Ainsi, E. aeneus présente une masse corporelle moyenne variant entre 38,18 ± 0,24 g et 409,81 ±1,39 g pour une longueur moyenne variant entre 10,48 ± 0,01 cm et 24,58 ± 0,04 cm. L. agennes présente une masse moyenne corporelle variant entre 35,16 ± 0,57 g et 452,12 ± 2,03 g pour une longueur moyenne variant entre 10,01 ± 0,02 cm et 22,3 ± 0,03 cm. M. cephalus présente une masse corporelle moyenne variant entre 49,15 ± 1,01 g et 637,83 ± 1,03 g pour une longueur moyenne variant entre 14,06 ± 0,2 cm et 28,32 ± 0,32 cm. Les trois espèces présentent donc de bonnes performances de croissance et peuvent être recommandées pour l’aquaculture béninoise.Mots clés : Elevage, Epinephelus aeneus, Mugil cephalus, Lutjanus agennes, Bénin. Marine aquaculture in benin: prospects for the breeding of Lutjanus agennes, Epinephelus aeneus and Mugil cephalus.Tests of breeding of Lutjanus agennes, Epinephelus aeneus and Mugil cephalus) were carried out in ponds for 12 months. A natural fertilization of the ponds and a food complementation of the subjects were used. Environmental parameters (temperature, salinity of water) and of the parameters of were measured. The results show a ponderal growth and in significant length from one species to another (p < 0.05) during the probation period. The results show a ponderal growth and in significant length from one species to another (p < 0.05) during the probation period. Thus, E. aeneus has an average body mass varying between 38.18 ± 0.24 G and 409.81 ±1,39 G for an average length varying between 10.48 ± 0.01 cm and 24.58 ± 0.04 cm. L. agennes has a body average mass varying between 35.16 ± 0.57 G and 452.12 ± 2.03 G for an average length varying between 10.01 ± 0.02 cm and 22.3 ± 0.03 cm. M. cephalus has an average body mass varying between 49.15 ± 1.01 G and 637.83 ± 1.03 G for an average length varying between 14.06 ± 0.2 cm and 28.32 ± 0.32 cm. The three species thus present good performances of growth and can be recommended for the Beninese aquaculture.Keywords: Breeding, Epinephelus aeneus, Mugil cephalus, Lutjanus agennes, Benin

Domestication de portunus validus et callinectes amnicola au Bénin

Afin de diversifier les espèces candidates à l’aquaculture béninoise, des essais de domestication ont été réalisés sur deux espèces de crustacés lagunaires, Portunus validus et Callinectes amnicola. Des essais de croissance basés sur le nourrissage sur production primaire des étangs (mis en charge de 100 individus) et sur complémentation alimentaire ont été faits en étangs vidangeables de 132 m2 pendant 12 mois en eaux saumâtres. Les paramètres morphométriques de croissance (largeur de carapace (LC), masse corporelle (MC), masse des pinces (MP) ont été mesurées. Les résultats ont montré des différences très significatives (p<0,01) entre la largeur de la carapace (LC)et la masse corporelle (MC) au sein d‘un groupe, d’une même espèce et cela indépendamment du sexe dans les deux systèmes de nourrissage, un fort coefficient de régression entre la masse des pinces (MP) et la masse corporelle (R2= 0,98 pour P. validus ; R2=0,97 pour C. amnicola) dans les deux systèmes de production au niveau des deux espèces quel que soit le sexe. En nourrissage sur production primaire, cette corrélation au niveau des mâles apparaît faible (P. validus = 0,2402 ; C. amnicola = 0,2770). Les pinces des femelles de chaque espèce présentent d’une manière générale une masse de 12,6 % inférieur à celle des mâles et la masse des deux pinces représente en moyenne 29,7 % de la masse corporelle. Avec une complémentation alimentaire, nous avons une augmentation de croissance de 7% chez P. validus et de 19% chez C. amnicola. Les performances morphométriques de croissance (LC, MC) des deux espèces dans le système d’apport de complément alimentaire montrent de bonnes perspectives dans la formulation alimentaire propice au développement de l’élevage de P. validus et de C. amnicola en aquaculture au Bénin.Mots clés : Aquaculture, Crabes, Portunus validus, Callinectes amnicola, Bénin.English AbstractIn order to promote the domestication of Portunus validus and Callinectes amnicola, the tests of growth based on the feeding on primary production of the ponds (batch 1: put in charge of 100 individuals) and on food  complementation were realized in drainable ponds of 132 m2 for 12 months out of brackish water. Morphometric Parameters of growth (width of carapace (LC), body mass (MC), Mass of grips (MP)) were measured. The statistical analyses of these data were made with STATISTICA version 7.1 and of the tests post hoc carried out. The results show very significant differences (p < 0.01) between the width of the carapace (LC) and the body mass (MC) within a group, of the same species and that independently of the sex in the two systems of feeding, a strong coefficient of regression enters the mass of the grips (MP) and the body mass (R2 = 0.98 for the P. validus; R2 = 0.97 for C. amnicola) in the two systems of feeding, on the level of the two species some is the sex. In feeding on primary production, this correlation at the level of the male appears low (P. validus = 0.2402; C. amnicola = 0.2770). The grips of the females of each species generally have a mass of 12.6% lower than that of the males and the mass of the two grips accounts for on average 29.7% of the body mass. The morphometric performances of growth (LC, MC) of the two species in the system semi-intensive (contribution additional food supplement) show good prospects in the food formulation favorable with the development for the breeding for P. validus and C. amnicola in Benin.Keywords: Aquaculture, Crabs, Portunus validus, Callinectes amnicola, Benin

International conference ICAWA 2016 : extended book of abstract : the AWA project : ecosystem approach to the management of fisheries and the marine environment in West African waters

Benin, like most African countries, is exposed to disasters due to climate risks. This includes strong winds, late and intense rains, floods and episodic ocean events including extreme swells. The latter accentuate the phenomenon of erosion and result in material damage along the coast. In order to limit damage and destruction caused by climatic variations and extreme events, the Climate Information Strengthening Project and the Early Warning System in Africa (SAP Benin) were set up in 2013. It is in the framework of this project that in December 2015, the IRHOB (Institute of Fisheries and Oceanic Research of Benin) received an oceanographic buoy (buoy Alizée) and installed it about 6km offshore of the port of Cotonou. The data of the buoy are sent by radio waves to the premises of the IRHOB and are analyzed in order to characterize the temporal variability of the wave, wind and current parameters. The analysis of the wave parameters allowed us to give a statistical assessment of the state of the sea in the region and to identify the strong events during the period from December 2015 to October 2016. These combined with the high tides have led to marine flooding

Shoreline and beach cusps dynamics at the low tide terraced Grand Popo Beach, Benin (West Africa) : a statistical approach

This paper presents the description of a 2-dimensional shoreline and 3-dimensional shoreline behaviour around a 'storm free' microtidal beach from a 3-year video observation using empirical orthogonal function (EOF) analysis. The EOF method is applied successfully to delineate 2D and 3D developments that show the beach evolution influenced by the action of waves and tides. The EOF model results are in agreement with measurements that reflect the morphological concepts for the 2D and 3D cases: the first temporal EOF mode which accounts for an overwhelming 80% of shoreline variation reflects the alongshore-averaged cross-shore migration (2D) largely influenced by waves while the higher eigenfunctions with 20% shoreline variation reflect beach deformation/irregularities (3D). Shoreline location is correlated to cross-shore energy flow from waves, while 3D is associated to the longshore energy flow. The influence of wave height increases cross-shore uniform migration and beach seasonality. The results show that with EOF method, beach cusps are clearly identified for 3D developments to be evaluated. Beach cusps are well observed at low tides on video images. Tide and cusps increase the importance of short term events and deformation; at the lowest high tide mark, beach cusps were observed on higher spatial functions of EOF. This indicates that a study of these morphological features as a coupled system, promotes their contribution in predicting 2D and 3D shoreline changes

The Bight of Benin, a North Atlantic breeding ground of a Southern Hemisphere humpback whale population, likely related to Gabon and Angola substocks. Scientific Committee document SC/53/IA21, International Whaling Commission, July 2001, London

Aiming to assess the feasibility for commercial whale-watching in coastal waters of Benin, exploratory boat transects were made from 12-19 October 2000. In 55h48min of observation, covering 349.6 nautical miles, 22 positive sightings of humpback whale and three ‘like-humpback whale’ groups were recorded. Relative group density was 0.448 sightings/hour observing or 0.072 sightings/nautical mile surveyed. Mean group size was 1.52 individuals (SD=0.92, range 1-5, N=25) and relative density 0.109 humpback whale/nautical mile. Additional evidence showed that other nations bordering the Bight of Benin, i.e. Ghana, Togo and Nigeria also are new Range States. Off Benin we observed three cow/calf pairs; one calf stranded in Ghana and more calves were reported from Togo. The calves, considering their small size and behaviour are thought to be born locally. Adult humpback whales often engaged in aerial display behaviour, including breaching, energetic surfacings, flipper-slaps, lob-tailing and spy-hopping. Two surface-active groups were seen, a behaviour linked to courting and mating. Occurrence off Benin and Togo is seasonal, from early August till early November. Although geographically situated firmly in the North Atlantic (boreal of 06°N), seasonality agrees with a breeding ground of a Southern Hemisphere population for which we propose the name ‘Bight of Benin substock’. Likely related to the IWC-defined Gabon and Angola substocks, combined these may form a wide-ranging Gulf of Guinea population. Overall sighting conditions were favorable and each of six trips resulted in at least one whale encounter, confirming whale-watching potential. A single ‘like-bottlenose dolphin’ group sighting was unrepresentative for small cetacean abundance when checked against frequent opportunistic observations. A collection of specimen identified as Pseudorca crassidens is the first record of false killer whale in the Bight of Benin

Waves forcing climate on Benin coast, and the link with climatic index, Gulf of Guinea (West Africa)

Benin's coastline is currently undergoing very marked erosion. This erosion is the consequence of the impact of swells from the South Atlantic and is accentuated by human development. These swells, from weak to moderate energies, drive Benin's coastline evolution. Although crucial, the characteristics of this forcing are not accurately defined. From instantaneous outputs of ERA40 and ERA-Interim's sea state parameters, the annual and seasonal average of significant wave height (Hs), peak period (Tp) and direction (Dir) were determined to characterize wave forcing and extreme event on Benin Coast after a validation using the data of the ALIZEE buoy installed 6 km off the coast of Benin in December, 2015. Hindcast data analysis indicates an important if increasing trend of Hs and Tp. A weak trend of peak direction towards the South West clockwise is observed between 1957 and 2016. The intra-annual variability of Hs shows a marked seasonality, the first one characterized by strong swells from April to October and the second one by moderate swells from October to April. Offshore wave height is positively correlated with AMO (Atlantic Multidecanal Oscillation)