Effect of Water Temperature on Embryonic Development of Yellowfin Tuna Thunnus albacares Inhabiting the Eastern Pacific Ocean

抄録

Effect of water temperature on embryonic development of yellowfin tuna was investigated. Eggs were incubated at different water temperatures: 22, 24, 26°C (Experiment-1) and 28, 30, 32°C (Experiment-2). Developmental condition was observed and the elapsed time from the 2 or 4 cell stages until hatching was measured. Hatching occurred at 18.58 h for eggs incubated at 32°C. Eggs incubated at 22°C stopped development after the morula (late cleavage) stage. Experiment-3 was designed to examine the relationship between hatching time and the incubation temperature, and was expressed by two regression lines which intersected at 26.9°C.