Spawning season, lunar-related spawning and mating systems in the camouflage grouper Epinephelus polyphekadion at Ishigaki Island, Japan
2008
Teruya, K.(National Center for Stock Enhancement, Shibushi, Kagoshima (Japan). Shibushi Station) | Masuma, S. | Hondo, Y. | Hamasaki, K.
We examined seasonal changes in the gonadosomatic index of wild fish and detailed the first spawning period of each year of cultured fish over several years to determine the spawning season and lunar-related spawning of camouflage grouper Epinephelus polyphekadion in a subtropical area of southern Japan. Additionally, we observed captive females' and males' spawning behavior and elucidated the mating system of this species. The main spawning season of wild fish was April-May of the solar calendar (Gregorian calendar), when gonadosomatic index (GSI) values of females and males peaked. The first spawning periods varied in the solar calendar. However, they were observed from the 19th to 23rd day in the third month of the lunar calendar (lunisolar calendar) during the full moon and the last quarter moon, excluding the years when spawning occurred one month later, because of low water temperatures before the spawning season in those years. This result indicates that camouflage grouper shows lunar-related spawning. The basic mating system of camouflage grouper is pair spawning between the largest dominant male and an ovulated female. However, some non-dominant males undertook sneaker spawning.
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