Comparative study on origin and formation of lunar-synchronized spawning in reef fish

为了阐明珊瑚礁鱼类与月亮同步产卵活动的起源和形成，对印度尼西亚爪哇中部热带珊瑚礁鱼类的年繁殖周期和产卵节律进行了研究。大多数研究都是用兔子鱼进行的，因为日本冲绳的亚热带珊瑚礁也进行了类似的研究。当鱼按月从珊瑚礁采集或从渔民那里购买时，大多数鱼都有一定的繁殖季节，发生在从干到湿或从湿到干的季节转换前后。在繁殖季节，根据农历周期每周采集一次鱼，以了解产卵节律。因此，兔鱼物种在繁殖季节重复与月球有关的产卵。例如，金兔鱼Siganus guttatus在上弦月前后发育性腺并产卵。印度尼西亚中爪哇和日本冲绳与月球相关的产卵活动对比显示，金兔鱼在相同的月相(上弦月)产卵。本研究表明，该鱼具有与区域环境密切相关的年度繁殖季节，并且在任何地区都可以利用来自月球的相同信号作为同步产卵的采样器。

In order to clarify origin and formation of lunar-synchronized spawning activities in reef fish, annual reproductive cycle and spawning rhythm of fish inhabiting tropical coral reefs in Central Java, Indonesia were examined. Most studies were carried out using rabbitfish, because similar studies have been conducted in sub-tropical coral reefs in Okinawa, Japan. When the fish were monthly collected from coral reef or purchased from fishermen, most fish had definite reproductive seasons, which occurred around changing season from dry to wet or from wet to dry. During the reproductive season, the fish were collected weekly according to lunar periodicity in order to know spawning rhythm. As a result, rabbitfish species repeated a lunar-related spawnings during the reproductive season. For example, the golden rabbitfish, Siganus guttatus, developed the gonads toward and spawned around the first quarter moon. Comparison of lunar-related spawning activity between Central Java, Indonesia and Okinawa, Japan, revealed that the golden rabbitfish spawned around the same lunar phase (the first quarter moon). The present study suggest that the fish have annual reproductive season which is closely related to regional environments and that the same cues from the moon are used as Zeitgeber for synchronized spawning in any regions.