Age, growth and condition of the Perth herring, Nematolosa vlaminghi (Munro) (Dorosomatinae), in the Swan Estuary, south-western Australia

Abstract

The size, age and condition of Perth herring, N. vlaminghi, in the Swan Estuary in south-western Australia, were investigated between February 1977 and January 1980 using samples collected by beach seine and gill net. An examination of scale annuli showed that the population consisted predominantly of age classes 0+ to 4 +. By the end of their first year of life, Perth herring had reached mean lengths of 105 mm (= 9.8 g) in 1977, 105 mm (= 10.0 g) in 1978, and 95 mm (= 7.9 g) in 1979. The von Bertalanffy growth equation was calculated to be Lt = 381{1 -exp[- O.17(t + 0.6S)]}. During winter, the growth rate declined markedly and the mean condition factor fell to its lowest level. Perth herring started to make a major contribution to the important commercial fishery for this species during their third year of life.