Impact of Floating Cage, Suspension and Bottom Culture Techniques on the Growth and Survival of the Mangrove Oyster Crassostrea tulipa in the Coastal Lagoon of Ouidah, Southern Benin

Abstract

Aims: Oyster farming remains an underdeveloped sector in West Africa, despite the importance of oysters in providing essential protein for local populations. The study aimed to compare the effectiveness of three farming techniques (floating cage, suspension, and bottom culture) in improving oyster growth. Study design: The study was carried out by rearing 640 mangrove oyster Crassostrea tulipa spat using three culture techniques (Floating Cage, Suspension technique and Bottom Culture) in                 four stations. At each station, 180 specimens of oyster were reared in the three farming             techniques: floating cage (60 oysters), suspension technique (60 oysters) and bottom culture (60 oysters). Place and Duration of Study:The specimens used in the study were collectedin Djondji village in coastal lagoon of Ouidah (Benin) and cultured during 60 days from September to October 2022 in four stations (Djègbadji, Sèyigbé, Dégouè, and Azizakouè) distributed along the lagoon. Methodology: For each technique, juvenile oysters (3.2 cm in length) were reared in locally adapted materials. Shell length, weight, and number of live and dead specimens were recorded at regular two-day intervals. Dead specimens are counted and removed from trials to assess mortality rates. Growth parameters (K and L∞) from the Von Bertalanffy equation, daily growth rate (GR), and survival rate were estimated for each trial. Results: The K values ranged between 0.046–0.041 day⁻¹, 0.065–0.064 day⁻¹, 0.063–0.060 day⁻¹, and 0.041–0.033 day⁻¹ for floating cage and suspension techniques at Djègbadji, Sèyigbé, Dégouè, and Azizakouè, respectively higher than those obtained for traditional bottom culture (0.030, 0.017, 0.009, and 0.012 day⁻¹ at the same stations). Daily growth rates reached 3–2.667 cm/day with floating cages, 2.667–2.5 cm/day with suspension culture, and 0.667–0.5 cm/day with bottom culture. Survival rates were significantly higher (86.67–96.67%) with the new techniques compared to traditional farming (48–50%). Conclusion: Crassostrea tulipa exhibited better survival and growth performance with the new techniques, particularly in floating cages, suggesting promising prospects for its aquaculture.