Ethno-ichthyological knowledge can improve fisheries management. This study covers interactions between ecological, morphological, and sociocultural aspects pertaining to the fish of the Tovè River, which is located in the largest fishing area in the Republic of Benin (Ouémé Valley), West Africa. In particular, data were collected on fishing methods and techniques, fishing equipment, and ichthyofauna by noting vernacular names followed by identification traits, taste and dietary value, medicinal use, and related knowledge of different species. Through data related to names given locally to fish, this paper highlights the manner in which physical or behavioral traits are coded in terminology. Most of these species have a high market value, either because they are considered to be delicacies and/or for their medicinal uses. The results suggest that ethno-ichthyological information can successfully be applied to improve fish conservation and fisheries management.

Sardinella maderensis is one of the fish species well appreciated in Benin. In recent years, this species has experienced a decrease in its production in the coastal waters of this country. To search for the causes of this decline in production, a standard survey was carried out using Computed Assisted Personal Interviewing with the 38 artisanal fishermen at the artisanal fishing port of Cotonou who targets this species in order to inquire about the fishing gear and techniques of production. The current stock status of this species was determined using FiSAT from a sample of 1240 specimens collected randomly in commercial catches from January to December 2021. The typical survey revealed a massive use of non-regulatory fishing mesh gear (86.85%). The fishing effort is also sustained and results in a fishing mortality rate (F = 2.88 yr −1 ) higher than the rate of natural mortality (M = 2.22 yr −1 ) suggesting overfishing of the stock. Sustainable management through capacity building of fishermen and application of regulations in terms of gear mesh size and respect for fishing seasons could be stated.

: The current study aims at determining the optimal usage conditions of rabbit manure in a multispecies fresh water algae production for fish farming. This purpose, the experimental design is made of six treatments in triplicate including one control T0, T1, T2, T3, T4, T5 corresponding respectively to 0, 300, 600, 900, 1200, 1500 g/m3 of dry rabbit manure put into buckets containing 40 L of demineralized water and then fertilized. The initial average seeding density is made of 4 × 103 ± 2.5 × 102 cells/L of Chlorophyceae, 1.5 × 103 ± 1 × 102 cells/L of Coscinodiscophyceae, 3 × 103 ± 1.2 × 102 cells/L of Conjugatophyceae, 2.8 × 103 ± 1.5 × 102 cells/L of Bascillariophyceae, and 2.5 × 103 ± 1.4 × 102 cells/L of Euglenophyceae. During the experiments, the effects of these treatments on abiotic and biotic parameters (chlorophyll-a concentration, phytoplankton density and algal density) of different production media were monitored. Results show that average density of different phytoplankton classes is higher in treatment T5 (7.91 × 108 ± 6.78 × 107 cells/L) followed by T4 (5.56 × 108 ± 4.27 × 107 cells/L), T2 (3.87 × 108 ± 3.10 × 108 cells/L), T3 (3.79 × 108 ± 3.18 × 108 cells/L, with high significant difference (F (4,84) = 5, 35, p < 0.00). Chl-a concentration varied from 0.07 ± 0.05 mg/L (T0) to 14.47 ± 12.50 mg/L (T5) with high significant differences observed among treatments (F (5,83) = 3,09, p = 0,01). In addition, fourteen (14) species belonging to eight (8) families, five (5) classes and three (3) phyla were identified in our different production media. During the culture, Chlorophyceae class was the most represented in all treatments with 5 species (36% of the specific diversity) while Euglenophyceae class (7%) was the least represented with only one (01) species. According to these results, treatments T2 (600 g/m3), T3 (900 g/m3) and T4 (1200 g/m3) of dry rabbit manure are those worthy to be recommended as an alternative for a low cost massive production of multispecies freshwater algae that can be easily used by freshwater zooplankton and macroinvertebrates. Indeed, despite the best performances that it shows, treatment T5, presents important eutrophication’s risks.

Cet article est distribué suivant les termes et les conditions de la licence CC-BY (http://creativecommons.org/licenses/by/4.0/ deed.fr) Description du sujet. Cette étude détermine les conditions optimales d'utilisation de déjections de lapin dans la production de macroinvertébrés benthiques pour une production de poisson à faible cout. Objectifs. L'objectif de cette étude est la détermination de la dose optimale de déjections pour une production plurispécifique de macroinvertébrés d'eau douce. Méthode. Pour ce faire, six traitements dont un témoin ont reçu respectivement 0 %, 10 %, 25 %, 50 %, 75 % et 100 % de déjections par rapport au volume total de substrat. Les cultures ont été réalisées dans des seaux qui ont chacun reçu au total 10 dm 3 de substrat, 16 dm 3 d'eau de forage et 4 dm 3 d'eau d'étang. La densité initiale d'ensemencement est de 6 ind . dm -2 d'Odonates et d'Annélides (soit 3 ind . dm -3 , pour une profondeur de 0,5 m), 8 ind . dm -2 de Chironomidae (soit 4 ind . dm -3 ) et 10 ind . dm -2 de Mollusques (soit 5 ind . dm -3 ). Les paramètres physico-chimiques et biologiques de la culture ont été suivis tout au long des 63 jours d'expérimentation. Résultats. Les densités les plus élevées de macroinvertébrés benthiques sont obtenues avec le traitement T 2 (192 ± 1,20 ind . dm -2 de Chironomidae, 52 ± 0,8 ind . dm -2 de Mollusques, 6 ± 0,33 ind . dm -2 d'Odonates et 4 ± 0,33 ind . dm -2 d'Annélides soit, 96 ± 1,20 ind . dm -3 de Chironomidae, 26 ± 0,8 ind . dm -3 de Mollusques, 3 ± 0,33 ind . dm -3 d'Odonates et 2 ± 0,33 ind . dm -3 d'Annélides). La biomasse la plus élevée des Chironomidae et des Mollusques est obtenue avec T 2 , soit respectivement 728,1 ± 2,23 mg de matière sèche . dm -2 et 699,98 ± 22,49 mg de matière sèche . dm -2 (ou encore respectivement 364,05 ± 2,23 mg de matière sèche . dm -3 et 349,99 ± 22,49 mg de matière sèche . dm -3 ). Conclusions. Au regard de ces résultats, le traitement T 2 (140 g de matière sèche . dm -2 , soit 75 g de déjections de lapin sèches . dm -3 de substrat) constituerait la dose à recommander pour une production plurispécifique optimale de macroinvertébrés benthiques d'eau douce. Mots-clés.

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