Report on Brackish Water/Coastal Aquaculture Development, Kenya: Preliminary Final Draft. A Report to the TCP/Ken/0051(A) Mangrove Conservation and Management.

Abstract

Kenya has a coastline of about 1420 km. Along the coastline, there are about 64 426 ha of mangrove forests with a large area near Lamu island and at the mouth of the Tana River. The mangrove forests play a significant role in maintaining the productivity of coastal fishery resources providing nursery ground and shelter for fish and shrimp. Shrimp farming and fish culture in brackish water pond are the main aquaculture systems that found attractive and having a high potential for alternative use of mangrove forests while the sea farming such as fish culture in net cages, oyster and seaweed culture can be a substitution of non-destructive aquaculture systems alternatives to pond culture. The benefit derived from shrimp farms are relatively high when compared with forestry products produced by natural managed mangrove. However the shrimp culture required a high capital input and expensive to maintain, and produced disappointing economic result due to low and declining productivity whereas a natural mangrove is a self sustaining. At present, only 3 950 ha of mangrove forests are found suitable for the brackish-water aquaculture development. 58% of the area are within concession of 'salt works. The remaining are 400 ha of the low ground area in Port Reitz, and 1000 ha of a high ground on the North bank of Tana river. The areas suitable for oyster culture are found along tidal creeks of Matondoni, Mto Pungani, Mto Wange and Mangoni in Lamu (100 ha About 5 ha in Paye of Manda Bay are suitable for netcage culture developments. In Mombasa, there are about 10 ha in Port Reitz, and 5 ha in Port Tudor suitable for Tilapia spilurus netcage culture and 15 ha in Gazi bay are suitable for Gracilaria culture developments. The salt farms occupied 7 922 ha of the tidal flats and swamps from the Ngomeni to Kurawa which 1000 ha are not being utilized. In addition to the existing salt works there are 800 ha of swamp land in Lamu are suitable for salt farms development. Brine shrimp culture offers another avenue for utilization of unproductive existing salt ponds without destruction of the mangrove forests. The economic return from brine shrimp farming is also high when compared with those derived from salt pond operations. The financial returns of the semi-intensive culture of P. monodon culture, the Tilapia culture in brackish-water and in netcages, and oyster culture in mangrove area are favorable whereas the extensive culture of P. indicus and marine fish culture in netcages, is not justifiable in economic terms due to high cost of production and low market value of the product in Kenya.