Growing Tilapia in Atlantic Seawater in St. Kitts

Small islands with no rivers or clay have always had to forgo assistance to develop aquaculture. With the rapid depletion of reef fishes in the Caribbean, St Kitts was forced to import fish for the local tourism industry and local consumption.

I would like to share the excitement of successfully growing Tilapia in 100% seawater inland. This project began in 1999 as a challenge, after learning that a fisherman in Jamaica caught a tilapia in his seine net. My background, as an administrator of government funding for community projects, led me to investigate the fisheries complex at Twickenham farm in Jamaica, where experimental brood ponds were in operation. I learned as much as I could and fell in love with aquaculture. Now, St. Kitts is one of the smallest islands in the Caribbean, with no running rivers or pond sealing clay. In addition, the public water supply is expensive. There is however the Caribbean Sea on one side and the Atlantic on the other. The first challenge was to find a suitable site for establishing the ponds. Eventually I had to settle for an 1/8 of an acre bordering the Atlantic, which was never calm. Lining up the ponds in the traditional wind flow was a job, additionally the ponds had to be above ground level, in order to counter hurricane flooding. This was all done by hand, sweat, blood and tears. Finally five ponds 100'x25'x4' materialized, lined with the thickest non-leaching polyurethane on the market. The lining was laid seamless by tucking the corners up and tacking the material when the sun was hot, on a frame, then backfilling to the required height. Piping was the next challenge. At first the Atlantic feed was difficult to stabilize, but a 4' cast iron sleeve did the trick, with a 2"schedule 40 PVC pipe threaded into it. A foot valve and strainer was attached to the end, which must be cleaned regularly, due to seaweed and sand. At 150' from foot valve to draft pump, priming was problematic, but solutions were found. One and a half miles of pipe was laid for freshwater, saltwater, groundwater, and included a 4" manifold for aeration. At this stage the project was still a zero based, out of-pocket budgeted effort, so the local land fill had to supply all the bits and pieces which was creatively utilized. Funding for the project is still a problem. Banks were skeptical when I told them I planned to grow freshwater fish in seawater. Funding agencies favored cooperatives or associations. As a development specialist I only thought of bring the idea to fruition and opening it up to replication. And so the struggle continued. Jamaica red snapper was the fingerling of choice. In year three the saltwater research began in earnest. Available expertise at a number of Universities, the Taiwanese, Norwegians and our local fisheries department advised 50/50 or at most 60/40, the greater being seawater, was the level of tolerance to be expected. Well, in pushing the envelope I experienced massive fish kills on numerous occasions, due to excessive algae growth ( I opted for green water culture), heat during June July and August, and excessive salinity. Each of these problems had to be solved as they occurred. Now, the whole project being a massive aquarium, water quality, ph, temperature etc became major factors. In topping up the ponds with pristine Atlantic sea water I realized my mistake, simply, evaporation by wind and sun only involves fresh water, the salt remains. The salinity soared and corned fish was the result. The heat problem was easy to solve. Partial shade netting worked wonders and a continuous flow of ground water, both addressed salinity and temperature. Ground water was found at 8' inland and slightly brackish. This gave rise to developing a flow-over system at the far end of the ponds, with a return path through sand under the ponds and back to the ground water well. Cool. I have since invested in a powerful Rotron Regenorative Blower which powers 8 air stone pods with a H configuration of air stones in each pond. In addition home-made airlift pumps were made out of PVC pipes, and small washing machine pumps turned upside down in a bucket to provide a 5' spray of water. During windless days these pumps helped to aerate and cool the ponds at minimal cost, The project could be considered to be at the 95% stage of completion. Salinity is still monitored by the taste test, while the project is on the hunt to secure funding for the various meters. Acclimatization was the most problematic hurdle as I struggled in the research to determine commencement stage, and all the other factors that had to be solved. It is now 7 years into the project cycle with acceptable success, except for petty larceny of fish and visits from fishing birds. The bird problem has been solved with dogs on pond long length guide wires and anti predator piano wire covering the area at 6" apart. Man however is a different story.

nvaluable technical assistance was received from Mr Humphrey Brown, Production Manager of Aquaculture Jamaica Ltd. and Mr. Sam Heyliger of the St. Kitts Department of Fisheries. The environmental component constitutes a 10' sand dune covered by a dense growth of 30' of sea grape which has been fortified by huge rocks in order to ensure the integrity of the dune.

There is now market size fish of 1 1b. and the first commercial sale was transacted on the 25th of March 2006. Customer feedback is positive, regarding ease of scaling, taste and size.

SNAPPER would be prepared to share experiences with anyone who is interested.