1National Research Institute of Aquaculture, Fisheries Research Agency, Shibushi, Kagoshima 899-7101, 2Seikai National Fisheries Research Institute, Fisheries Research Agency, Ishigaki, Okinawa 907-0451, 3Marine Fisheries Research and Development Center, Fisheries Research Agency, Yokohama, Kanagawa 220-6115, 4Hokkaido National Fisheries Research Institute, Fisheries Research Agency, Kushiro, Hokkaido 085-0802, Japan
Under the current rearing conditions (control) of eel larvae, the larval period of Japanese eel Anguilla japonica in captivity is longer than that in nature. In this study, we first investigated the effects of feeding frequency and rearing temperature on larval growth and survival. Based on these results, we demonstrated that eel larvae grew faster than the control by three modifications: rearing at higher temperature, feeding at higher frequency and decreasing the number of rearing larvae by dividing them into several rearing tanks. As a result, we obtained an average larval period of eel of 210 days from hatch to completion of metamorphosis, in contrast to 303 days in the control. These results suggest that careful modifications of rearing conditions can shorten the larval period of eel.