Fish abundance and distribution in the Gamtoos estuary with notes on the effect of floods

Abstract

Gillnets were used on two occasions during 1980 and from January 1981 to January 1982 to determine the catch per unit effort for fishes in the Gamtoos estuary. The mean of the fish caught was 43 fish per net (33,3 kg), which compares favourably with other larger systems like the Sundays, Bashee and Kei estuaries. All these estuaries are subject to regular floods and have relatively small mudflats and Spartina beds in the mouth areas. Flood conditions, which occurred during seven months in 1981, caused reduced salinities and high turbidity throughout the estuary and were negatively correlated with catch returns. Mullet (Fam. Mugilidae) dominated catches numerically (12 per net) followed by kob Argyrosomus hololepidotus (11,4), sea-catfish Tachysurus feliceps (10,9) and leervis Lichia amia (5,2).