Tidal and turbidity effects on the shallow-water fish assemblage of Kuwait Bay

Abstract

Effects of location, diel period, tidal condition and water clarity on the size and distribution of the shallow water fish assemblage of the non-estuarine Kuwait Bay, were investigated using a beach seine and a small research trawl during spring and summer 1989. Total numbers, biomass and numbers of species differd markedly between Doha, a sandy shore environment, and Kazmah, an extensive intertidal mud flat. When fish were present in large numbers there was a marked diel effect at both locations with many more fish captured during the night. Tidal effects were influenced by turbidity and the age structure of the assemblage. In clear water during spring, very young Liza carinata from the seine catches formed shoals at the edge of the rising tide both day and night, while fish 2 mo older formed shoals only on daytime rising tides. At Kazmah during spring, high turbidity obscured any tidal effects in the seine catches. In slightly deeper water, sampled by trawl during spring, Leiognathus decorus showed an asymmetrical tidal migration.