In keeping with the mission's terms of reference which were specifically addressed toward shrimp farming, we have restricted our discussions within the assigned framework. However, during the course of our work, we cannot help but make certain observations which go beyond shrimp farming. Having, we believe, fulfilled the task assigned to us, we cannot resist, and in fact we feel professionally obliged, to share some of our thoughts regarding coastal aquaculture development in Kenya.
It is regrettable, we believe, that project KEN/80/018, Development of Coastal Aquaculture, very early on, dropped the finfish component of the project and concentrated on P. indicus. This has resulted in the total exclusion of food fish production. Considering the still low per caput fish consumption in Kenya of 3.5 kg (1978) due reportedly to insufficient supply, it would seem peculiar to orient coastal aquaculture development to the production of what is essentially a luxury crop: shrimps.
The reason advanced for the exclusion of finfish in the Coastal Aquaculture Project's programme is the paucity of the natural supply of rabbitfish and mullet fry. It would seem that the project should have explored the possibility of using what would seem to be the most obvious choice in terms of market acceptance, ease in breeding, feeding habits, hardiness and productivity: the tilapia.
While primarily a freshwater group of species, some Tilapia species show remarkable tolerance to salinity, surviving and even growing in sea water. Tilapia's feeding habits make it possible to realize fairly high yields even without introducing supplemental feed. Its hardiness would make it possible to farm them in shallower ponds and with less water exchange rate than for shrimp, although growth rates may be relatively low. This would effectively extend the elevation range that could be used for tide-dependent systems to as high as 3.0 m above datum. Many of the areas deemed marginal for tide-dependent shrimp farming would be acceptable for tide-dependent Tilapia farming.
Since breeding of tilapia under a saline environment is a problem, the fingerlings will have to be produced in freshwater hatcheries, transported, and properly acclimated to salt water prior to stocking. Saltwater tilapia culture is by no means a new idea. In fact FAO has an ongoing project in Jeddah in which T. spilurus from Kenya is being cultured in cages at the Red Sea where salinity is often above 40 ppm. This also raises the prospects of tilapia cage culture in the rich, sheltered waters within Port Reitz, Port Tudor and perhaps along many of the tidal creeks within Lamu. Cage culture is one of the few aquaculture systems that lends very well to dissemination among the poor due to the generally much lower minimum investments involved, providing that suitable fishfeed is available.
We noted also the profuse growth of oysters in Lamu and wonder whether a market could perhaps be established to make oyster farming in Lamu a worthwhile venture. We thought it a pity that the vast tracts of barren tidal flats turned out to be unsuitable for conventional pond construction, and tried to imagine how they might be made productive. We noted that in many of these tidal flats, hypersaline water often appears once the ground is dug up to half a meter depth. This raises the possibility of excavating large areas to construct what essentially would be man-made undrainable hypersaline lagoons.
Of what possible use would these hypersaline lagoons be? Suppose they are seeded with Artemia and suppose the Artemia propagates and thrives. Imagine the livelihood potentials that Artemia cyst gathering would generate. Imagine the number of poor fishermen who would benefit. It would be a perfect product for the relatively inaccessible Lamu. Artemia cysts have a very long shelf life. Lamu after all may still hold promises for coastal aquaculture development: a more diversified approach is the key.
