Reproduction and embryonic development in the African freshwater prawn Macrobrachium macrobrachion (Herklots, 1851)

The current study aimed to determine parameters and conditions for successful reproduction of Macrobrachium macrobrachion (Herklots, 1851) in a controlled medium and describing its embryonic development. A total of 122 adult specimens were collected from the delta of Ouémé River and stored in polyethylene tanks with 1:2 male-female sex ratio. This broodstock was fed on pelleted food (Biomar Efico) once a day. For the embryogeny monitoring, eggs were sampled each hour through the first two days after spawning and then every 2 hours till hatching. Spawning happened at a mean temperature, dissolved oxygen concentration and pH of 27.80±0.56°C, 5.83±0.45 mg/L and 7.41±0.34, respectively. The eggs incubation meantime was 12±1 days with nine main embryonic development stages. Hatching lasted on the average 21.00±1.94 h and led to larvae with a mean size of 2.30±0.90 mm. Mean fecundity was 13062.4±5489.93 eggs and 14715.2±6108 eggs, respectively for the first and second seasons with a highly significant difference between them. The best hatching rates were obtained with salinities equal to 2 and 4‰. The results constitute the first database for larval breeding of M. macrobrachion species

Geographical variation of the structure and population parameters of the freshwater prawn Macrobrachium macrobrachion (Herklots, 1851) in West African coastal hydrosystems: Insights from Benin

Abstract The freshwater prawn Macrobrachium macrobrachion (Herklots, 1851) is widely exploited in the Oueme Delta and the low Mono in Benin. The structure and population parameters of M. macrobrachion were evaluated to provide accurate scientific information for the better exploitation and rational management of freshwater prawn species in these areas. In Oueme Delta (1928 specimens) and low Mono (1045 specimens), 2973 specimens were sampled by artisanal and experimental fishing and analysed. The prawns were caught between January and December 2016. Total length and total weight were taken from each specimen. Global and monthly size–frequency distributions showed that recruitment in both populations takes place from August to October with a peak in September. The population parameters obtained by analysing frequency data with FiSAT II software (FAO‐ICLARM) showed an L∞ = 15.50 cm, K = 0.35 year−1, t0 = −0.56 year in Oueme Delta and L∞ = 15.30 cm, K = 0.45 year−1, t0 = −0.43 year in low Mono. The growth performance index (Φ′) was 1.93 and 2.02 for the Oueme Delta and low Mono populations, respectively. The exploitation rates (Emax and E0.5) suggest that more than half of the M. macrobrachion population was exploited in the two areas. Natural and fishing mortality rates showed that both populations of M. macrobrachion were vulnerable to natural and fishing death. The estimated first capture size (Lc) revealed that the majority of the two populations of M. macrobrachion were captured before they reached the size at first sexual maturity (L50), reflecting fishing pressure on small individuals and growth overfishing in both areas. These results showed that the used fishing gears and the fishing frequencies in both areas did not allow the majority of the prawn to grow and reproduce at least once before being caught

Yolk resorption and larval development in the brackish river prawn Macrobrachium macrobrachion under laboratory conditions: Perspectives for aquaculture

Macrobrachium macrobrachion is an African native brackish river prawn with a high commercial value. Currently, there is little information on the post-larval production of this species. Two experiments were conducted in the laboratory to develop production techniques for this species. The first experiment analyzed the duration of yolk resorption and the second described the larval stages. Yolk resorption was studied in 240 newly hatched larvae for 24 h based on the reduction in yolk area over time. For larval development stages, six breeding tanks containing 100 L with a density of 50 larvae/L were used. Larvae were fed a combination of Artemia nauplii, Brachionusplicatilis, and pelleted food (Larviva ProStart, Biomar Efico). The results have shown that the area of yolk reserves varied significantly in the hours after hatching. At 14 h after hatching, each larva resorbed approximately 85% of its yolk reserve, and at 18 h after hatching, each of them still had approximately 6.1%. Twelve larval stages were identified and described in three critical stages. M. macrobrachion larvae are lecithotrophic and need to start exogenous feeding at 14 h at the earliest and 18 h at the latest after hatching. These results are the first to highlight the potential for mass production of brackish river prawns.Fil: Koussovi, Guillaume. National University of Agriculture; Benín. Gaston Berger University; SenegalFil: Houssou, Arsène Mathieu. National University of Agriculture; BenínFil: Daves, Dimas Armando Orés. National University of Agriculture; BenínFil: Niass, Farokh. Gaston Berger University; SenegalFil: Bonou, Clément Agossou. University of Abomey-Calavi; SenegalFil: Lopez, Laura Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental. Laboratorio de Biología de la Reproducción y Crecimiento de Crustáceos Decápodos; ArgentinaFil: Montchowui, Elie. National University of Agriculture; Bení