Modified Taylor Float System for Culturing Oysters in The Gambia

Rice of the University of Rhode Island's Department of Fisheries, Animal & Veterinary Science. The study aimed to develop a low-cost oyster culture system for women oyster harvesters in The Gambia. The traditional oyster harvesting method in The Gambia involves collecting oysters from mangrove prop roots, with women typically working early in the season at accessible sites closer to their homes. However, as the harvest season progresses, they venture farther afield and deeper into the mangrove forest in search of larger marketable oysters. This method results in a significant amount of by-catch, including smaller non-marketable seed oysters that are simply culled and discarded. The Modified Taylor Float System is designed to reduce this by-catch and provide women with a convenient opportunity to learn a simple aquaculture technique to grow and sell the discarded seed oysters. The system uses Taylor floats, which were originally designed by Jake Taylor at the Virginia Institute of Marine Sciences Laboratory. The floats are constructed of plastic mesh or wire-coated mesh material with floatation provided by capped PVC piping. The Gambian variant of the Taylor float basket uses vinyl-coated wire mesh material as a substitute for plastic mesh, which is not readily available in the country. The materials for construction of the Gambian design were found at hardware supply and automotive supply houses in the Metropolitan Banjul area. The total materials cost for construction of the Gambian design was GMD 987.00 or about US$32.90. The pilot study was begun in January 2011 involving women oyster harvesters from the village of Kubeneh who saved small-sized seed oysters from their traditional harvesting and placed 150 of these seed oysters into each of two floats. The study continued until July 2012 at which time the study was concluded, and the oysters were taste tested by the women of Kubeneh. Oysters reached an average shell height of about 45mm, ranging from about 30mm to 55mm, matching the growth rates of oysters that the women typically see in the wild. The women reported only two oyster mortalities among the two bags or a 0.67% gross mortality percentage. They also reported that the shucked meat volume of oysters cultured in the floats would be about 3 cups (approx. 700ml) worth a total about GMD60 (about GMD30 = US$1) at their usual market outlets. Despite the unfavorable economics of using Taylor float baskets for culturing Gambian oysters, the experience of constructing, stocking, deploying, and tending the float baskets was reported by the oyster women to be a valuable learning experience. They gained an appreciation for the idea of using some sort of aquaculture technique to raise and profit from oyster seed that otherwise would be discarded and lost. They came to the opinion that farming oysters in baskets closer to home would be a valuable savings of time over their usual practice of traveling further and further into the mangrove estuary in search of market-sized oysters as the harvest season progressed. The women also stated that farming of oysters in the float baskets was a safer practice than venturing deep into the mangroves, and they stated that the float baskets allow for the availability of oysters to sell on a year-around basis. An added advantage arises from the fact that damage to mangroves is minimized, because cutting of mangrove prop roots or scraping bark of the roots is minimized as harvest pressure on wild oysters is reduced. For the various reasons stated by the women, and despite the high material cost of the two prototype Taylor float baskets, the women restocked the baskets with 200 oysters per float, indicating a potential for the Modified Taylor Float System to be a viable option for oyster culture in The Gambia.