The effect of salinity on jungle perch Kuhlia rupestris egg buoyancy and larval hatch rates

Abstract

This paper reports on the first ever observations of jungle perch Kuhlia rupestris egg buoyancy and hatch rates over a range of salinities and represents important information for the husbandry of this species. Dead or unfertilized jungle perch eggs tend to sink in static seawater (>34,000 mg/L), whereas fertilized eggs tend to float. However, at salinities below 32,000 mg/L most fertilized eggs also sink, making it difficult to separate them from unfertilized eggs. Separating fertilized from unfertilized and dead eggs is important for maintaining water quality in aquaculture hatch tanks. Hatch rates of fertilized jungle perch eggs were significantly higher (p < 0.05) at salinities at or above 32,000 mg/L than at lower salinities. The highest mean buoyancy and hatch rates were recorded at 36,000 mg/L. This suggests that jungle perch are fully marine, rather than estuarine spawners. It is recommended that fertilized jungle perch eggs be held at salinities of 32,000 mg/L or higher to maximize hatch rates and to facilitate removal of dead egg material from hatch tanks.