Growth of the mangrove oyster crassostreagasar (deshayes, 1830) reared with suspension techniques on the coastal lagoon in benin, west africa

The exploitation of the mangrove oyster Crassostreagasar is an income-generating activity for the riparian populations of the lagoons of southern Benin. The traditional bottom farming is the most widespread oyster farming method along the coastal lagoon. This study aims to cultivate the oyster with suspension techniques in order to increase oyster production. Rearing trials were carried out between September and October 2017 with vertical suspension technique, horizontal suspension technique and the floating line in different stations. At each station, both a suspension technique and traditional oyster culture method were experimented. Juveniles oyster of 50 to 54 mm size were cultivated .The growth parameters (K and L∞) of the von Bertalanffy equation as well as the growth rate were estimated and the survival rate was calculated for each of the trials. Growth parameters recorded for vertical suspension (K= 0.055 day-1; L∞ = 95.35 mm), horizontal suspension (K= 0.154 day-1; L∞ = 65.21mm) and floating line(K = 0.055 day-1; L∞ = 93.78 mm) are higher than the values of the same parameters for traditional rearing (K between 0.054 and 0.113 day-1; L∞ between 60.024 and 84.15 mm). Daily growth rates reached 0.31; 0.33 and 0.36 mm/day with the new techniques respectively in Dégouè, Sèyigbé and Djègbadji while they are 0.14; 0.17 and 0.19 mm/day in the same order. Survival rates are higher (95 to 97.5%) in the suspension techniques in contrast to the traditional farms (67.5 to 80%). The oyster C. gasar showed better survival rate and growth performance with the suspension techniques indicating promising prospects for its culture.