Influence of prey availability on the distribution of Dusky Kob argyrosomus japonicus (sciaenidae) in the Great Fish River Estuary, with notes on the diet of early juveniles from three other estuarine systems

The stomach contents of 391 juvenile dusky kob Argyrosomus japonicus (23–805 mm total length, TL) from the Great Fish River estuary were analysed. Early juveniles (400 mm TLfed on several teleost species, including early juvenile conspecifics, but their most important prey item was G. aestuaria. Based on the distribution patterns of A. japonicus and their predators and prey in the Great FishRiver estuary, it is concluded that predator avoidance and prey availability determine the spatial distribution of early juveniles in estuaries, and that the distribution patterns of larger juveniles (>400 mm TL) depend onthose of their principal prey. Important prey items of early juvenile from three other estuarine systems included calanoid copepods, mysids, insects, amphipods and swimming prawns. The impact of reducedfreshwater inflow on the abundance of the principal prey items of A. japonicus, and on the nursery potential of estuaries, is discussed