Lunar periodicity in spawning of white grunt, <I>Haemulon plumierii</I>

Abstract

Understanding lunar periodicity in spawning is necessary for guiding studies on reproduction in fishes, but is unknown for the abundant and economically important white grunt, Haemulon plumierii (Lacepede, 1801). We sampled mature white grunts in the eastern Gulf of Mexico during each of the four lunar periods of April 2016, coinciding with the seasonal peak of their spawning activity. Spawning-capable white grunts were macroscopically distinguishable from actively spawning fish, which we further confirmed microscopically. There was a clear lunar pattern with peak oocyte hydration and presence of flowing milt (i.e., actively spawning fish) during the full moon. A full moon spawn may be advantageous to juveniles settling during the following new moon after a short pelagic larval duration previously determined to be approximately 14 d. These findings can guide future research seeking to quantify either batch fecundity or production of white grunts by identifying the lunar period during which sampling should occur.