Distribution and abundance of eggs of the anchovy, Engraulis australis antipodum Gunther, in relation to temperature and salinity in the Gippsland Lakes

Abstract

Observations on the abundance of anchovy eggs in the Gippsland Lakes were made. From these observations, the duration and extent of spawning were inferred. Ten stations along the main salinity gradient were sampled from November 1978 to March 1980. Egg densities ranged from 1 to 38 170 eggs per 100 m³, densities of over 1000 eggs per 100 m³ being recorded on 16 occasions. Larval densities were much lower, only five records being greater than 100 larvae per 100 m³. Spawning extended from October to March. Peak egg and larval densities occurred in January for the two spawning periods examined. Eggs were found from McLennans Strait to the Entrance, with a few also collected from Bass Strait. Limited spawning did occur in the La Trobe River and in Lake Wellington during the 1967-1968 drought, when salinities were considerably higher than normal. The mean 'bottom' to 'top' density ratio for eggs was 3.8 to 1, probably as a result of vertical differences in salinity. Eggs were collected over a temperature range of 14.8-24.2ºC, although the main spawning occurred above 18ºC. The observed range in salinity was 2.3-35.5, but egg numbers in water below 15.8 were very low.