The effect of salinity on the eggs and Larvae of grey mullet, Mugil cephalus

Abstract

The effect of salinity on grey mullet eggs and larvae has been studied at room temperature and under natural photoperiod. Eggs were artificially fertilized and incubated at different levels of salinity in 1.5 liter aerated incubators. Percentage of surviving eggs expressed as percentage of pigmented embryos, percentages of hatched larvae, and larval survival were investigated. Incidental observations on eggs and larval suspension, as well as rate of heart beat at different salinities were obtained. Although the present study needs further detailed and more comprehensive experiments, it can be said that: (1) Optimum salinity for eggs incubated at 22°-24°C was 22-23 ‰. (2) Hatching occurred in all salinities from 15 to 42 ‰ and percentages of hatching generally increased with increasing salinities. (3) Optimum salinity for 2 day old larvae was around 23 ‰ , lower than that of newly hatched and 1 day old larvae. (4) The salinities of neutral buoyancy changed from 33 ‰ for fertilized eggs to 30 ‰ for pigmented embryos and to 25.5 ‰ for newly hatched larvae.