Evaluation of optimum temperature for the early larval growth of Japanese eel in captivity

Abstract

Early larval growth of the Japanese eel Anguilla japonica reared at five different water temperatures (19, 21, 23, 25, and 27\xa0°C) is described for the first month post-hatching, a critical period of time in the culture of these sensitive larvae. After 3\xa0weeks of culture, larvae reared at 27\xa0°C attained the greatest total length and body height of all temperature treatments. Larvae reared at higher temperatures developed rapidly due to active feeding, despite higher metabolic costs. At lower temperatures of 19–21\xa0°C, sudden mortality 12–16\xa0days post-hatching coincides with the transition of larvae from endogenous to exogenous feeding. A linear relationship between water temperature and otolith diameter for cultured eel larvae otoliths suggests that the mean ambient water temperature experienced by wild larvae during their first month after hatching is about 23\xa0°C. This temperature corresponds to mean water temperatures likely experienced by larvae during diel vertical migrations in the North Equatorial Current. We propose rearing early stage Japanese eel larvae at variable temperatures throughout the light/dark cycle to enhance their survival and growth in captivity.