Spawning Aspects of the Grey Mullet, Mugil cephalus L. Living on the Coastal Region of Kochi Prefecture

Abstract

The mature grey mullet, usually called “Karasumu-bora”, were examined based on the materials taken from the coastal water of Kochi Prefecture, Pacific coast, Shikoku Island, Japan.There is a tendency that the size of mature female is larger than ripe male;the former measuring 32 to 56 cm in standard length and the latter 27 to 42 cm. The ovarian eggs grow larger gradually from September to early October, when the eggs are small measuring less than 0.04 mm n in diameter, but they grow faster thence up to early November, when they gain the diameter of about 0.7 mm.The spent females are found only in the first decade of November in the area surveyed, while, the ripe males occur during the middle of October and early November.Various evidence thus accumulated will suggest the spawning of the grey mullet, Mugil cephalus taking place from late October to early November in the coastal water of Kochi Prefecture.
(Department of Cultural Fisheries, Faculty of Agriculture, Kochi University Nangoku City, Kochi Prefecture, Japan)