Onset of estivation in western sand lance Ammodytes japonicus is not solely triggered by elevating water temperature

Western sand lance Ammodytes japonicus exhibits dormancy in summer known as estivation, a distinctive ecology among teleosts. Estivation starts in early summer and continues until winter even water temperature lowered than the initiation threshold. In this study, we examined the onset of estivation in western sand lance reared under two experimental conditions of 14–25 °C-shift or 12 °C-constant. Our observations revealed that estivation in this species can be induced by intrinsic circannual rhythms other than either high or fluctuating water temperatures.