Effects of water temperature on embryonic development and hatching rate in three-lined tonguefish, Cynoglossus abbreviatus

Abstract

The effect of water temperature on the time taken to reach each embryonic developmental stage and on hatching rates were studied in the three-lined tonguefish, Cynoglossus abbreviatus. Eggs hatched at temperatures ranging from 13 to 24°C. The time between each developmental stage of eggs decreased exponentially with increasing temperature. The time taken from spawning to first hatching decreased from 102 hours at 13°C, to 30 hours and 30 minutes at 24°C. An intersection between regression lines was observed at approximately 20°C, when the logarithm of time taken from spawning to hatching was plotted against water temperature. More than 50% of all eggs hatched normally at temperatures ranging from 13 to 20°C and eggs incubated at temperatures ranging from 13 to 24°C produced normal hatched larvae. The relationship between normal hatching rate and water temperature was expressed by a curve, with a maximum value of 15–17°C. We conclude that 15–17°C is the optimum water temperature for embryonic development and hatching of the three-lined tonguefish. This coincides with the water temperature observed during the peak natural spawning season in Okayama Prefecture, Japan, for this species.