Vol. 46 No. 6, 2007
Evidence of Flathead Mullet Mugil cephalus L. Spawning in Waters Northeast of Taiwan
Chih-Chieh Hsu, Yu-San Han, and Wann-Nian Tzeng*
Institute of Fisheries Science, College of Life Science, National Taiwan University, Taipei 106, Taiwan
Chih-Chieh Hsu, Yu-San Han, and Wann-Nian Tzeng (2007) A new spawning ground for flathead mullet (Mugil cephalus
L.) in waters northeast (NE) of Taiwan was identified using comparisons
of the maturation status of fish to that of well-known spawning grounds
in waters southwest (SW) of Taiwan from 20 Nov. 2005 to 12 Jan. 2006.
Similarities in hydrographical conditions between the NE and SW waters
produced concurrent oceanic fronts with 20-23°C isothermal lines,
temperatures which are suitable for mullet spawning in both areas. Mean
fork length, body weight, the gonadosomatic index, and gonadal
maturation of mullet in the NE waters were all comparable to those in
the SW waters in the spawning season around the winter solstice (21 or
22 Dec.) ± 10 d. The gonadosomatic index of mullet in the NE waters
significantly increased from < 0.5 at the beginning of the spawning
season to greater than 21.0 for females and 19.0 for males at the peak
of the spawning season. Oocytes were all either late-stage vitellogenic
or post-vitellogenic from mid-Dec. to midJan. In addition, a few
individuals with hydrated oocytes or post-ovulatory follicles were also
found. This evidence suggests that waters NE of Taiwan are a suitable
spawning ground for the flathead mullet.
Key words: Mugil cephalus, Maturation, Spawning ground, Kuroshio Current, China Coastal Current.
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