Fishes of a shallow tropical mangrove estuary, Gazi, Kenya

Abstract

The composition and abundance of teleosts in an estuarine mangrove bay, sampled with a beach seine-net, are described. Site 1, at the mouth of a small river, was fringed by mangroves and had a silty substratum; Site 2 was also mangrove-fringed but had a sandy substratum and seagrass patches; Site 3 had a muddy sand substratum and also supported seagrasses. In total, 128 teleost species belonging to 50 families were identified in samples collected over 12 months. Gerreidae, Atherinidae and Clupeidae accounted for 78.5% of the total number of fish. Juveniles were found for 63% of the species. Of the fish species found, 44% were species associated with coral reefs. The mean numbers of species were similar at all sites, despite the differences in substratum type. Ecological diversity indices were higher, and fish density and biomass were lower, in the mangrove-fringed silt site than in the seagrass sites. Mean number of species was highest in February and June. Most families of commercial fish sought by fishers in the area were represented in the samples.