30 June 2012 early 1980s through collaboration between the Gambian Department of Fisheries, Catholic Relief Services, and the United States Peace Corps, focusing largely on the introduction of small-scale tilapia farming to small villages along freshwater portions of the river. This effort was short-lived but provided practical experience for Gambian fisheries officials who participated in subsequent efforts to culture tilapia and other freshwater fish (Jallow 2009). Problems with these initial projects included poor site selection, with ponds that were built on leaky laterite soils, and an unwillingness to co-opt space from rice farmers, a crop that was considered by many to be more profitable.4 Renewed interest in freshwater aquaculture began in 2008 with a UN-FAO sponsored review of fisheries regulations that recommended more stringent enforcement and penalties for illegal fishing, particularly in the upper freshwater reaches of the Gambia River. Additionally technical assistance to establish freshwater aquaculture was provided to the Gambian Department of Fisheries and the Department of Agriculture by the Taiwan Technical Mission. A number of factors, including the relatively low availability and consumption of fish in the inland areas of Gambia, also make revival of efforts to introduce freshwater fish culture an attractive prospect. Several species of cichlid fish (mostly tilapias) are native to the Gambia River and are easily cultured. In addition to tilapias, other available species amenable to culture include the African catfish, Clarias gariepinus; the African arowana, Heterotis niloticus; and the African knife fish, Gymnarchus niloticus. The Gambian Department of Agriculture maintains a series of demonstration Fig. 2. Water supply and drainage canal for Sapu tilapia ponds. Photo by Famara Darboe. Fig. 3. Manual soil compactors constructed with sticks held in concrete poured into 4-L metal cans. Photo by Famara Darboe. rice farms at Jahili-Medina near the village of Sapu (13.546oN, 14.894oW) that are irrigated by waters from the Gambia River. This region is Gambia’s premier rice producing region because the Gambia River there is freshwater year-round and there is enough tidal amplitude to allow periodic flooding of fields (Snead 1967). Construction of fishponds then became simply a modification of existing rice paddies using techniques introduced from Taiwan. With major funding provided by a Technical Cooperation Program grant from the UN-FAO, site selection was undertaken in March 2009 with attention to soil type and determination of proper elevation for a water supply canal (Figure 2). Construction of 20 ponds began in April 2010 and pond bottoms were excavated to an elevation 1.0 to 1.3 meters below the spring high water level to allow for pond filling. To assure proper gravity drainage, pond bottoms are above the low spring water tidal level. Ponds are roughly 340 m2 in area (about 25 m x 13.5 m). Due to characteristic heavy seasonal rainfall during July, August and September, dikes were constructed with adequate height using soil excavated from pond bottoms, resulting in a freeboard of about 70 cm, a dike crest width of 60 cm, and base width of 300 cm. As dikes were being constructed, fish farmers used hand-made manual soil compactors to assure that each soil layer was adequately compacted (Figure 3). Water is supplied to all ponds through a pre-existing tidal canal first constructed for rice paddy irrigation. The supply canal draws water directly from the Gambia River and flow is controlled by a main sluice gate. Water supply and drainage of each pond is by a concrete monk drain system at the deepest part of the pond nearest to the water supply and drain pipe traversing the water supply canal dike. As part of the system to protect dike integrity, emergency spillways are provided to allow rapid drainage of water during the rainy season. Shallow-rooted creeping vegetation was encouraged to grow on the dikes to minimize erosion (Figure 4). When ponds were built, broodstock of Nile tilapia Oreochromis niloticus captured from the wild were stocked into a designated spawning pond (Jallow 2011a). Each of the remaining 19 production ponds was stocked with about 10,000 fish per pond and fed a locally produced diet consisting of rice bran, peanut cake, wheat flour, locally
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