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Vol. 49 No. 4, 2010
The Migratory Environmental History of Freshwater Resident
Flathead Mullet Mugil cephalus L. in the Tanshui River,
Northern Taiwan
Chia-Hui
Wang1, Chih-Chieh Hsu1,2, Chih-Wei Chang3,4,
Chen-Feng You1, and Wann-Nian Tzeng2,*
1Earth
Dynamic System Research Center, National Cheng Kung University, 1
University Rd., Tainan 701, Taiwan
2Institute of Fisheries Science, National Taiwan
University, 1 Roosevelt Rd., Sec. 4, Taipei 106, Taiwan
3National Museum of Marine Biology and Aquarium, 2
Houwan Rd., Checheng, Pintung 944, Taiwan
4Institute of Marine Biodiversity and Evolution,
National Donghwa University, 1 Da-Hsueh Rd., Sec. 2, Shoufeng, Hualien
974, Taiwan
Chia-Hui
Wang, Chih-Chieh Hsu, Chih-Wei Chang, Chen-Feng You, and Wann-Nian
Tzeng (2010) The diversity of the migratory environmental
history of freshwater resident flathead mullet Mugil cephalus was
examined by analyzing the otolith elemental composition of mullet (n =
31) collected in midstream of the Tanshui River, northern Taiwan by
laser-ablation inductively coupled plasma mass spectrometry. The
mullet averaged 300 ± 33 mm in fork length and 410 ± 141 g in body
weight, and all were sexually immature at 1+ and 2+ yr old.
Strontium (Sr)/calcium (Ca) and barium (Ba)/Ca ratios in the otolith
core indicated that the mullet in the river were from 2 different
groups. Group 1 (18%) fish had higher Sr/Ca ratios and lower
Ba/Ca ratios in the otolith core region. Group 2 fish (82%) were
opposite to group 1, with higher Sr/Ca ratios and lower Ba/Ca ratios in
the otolith core region, indicating that these mullet had resided in
offshore waters in early life. Beyond the core region, the Sr/Ca
and Ba/Ca ratios alternately varied, indicating that the mullet
migrated between brackish and freshwater habitats after the juvenile
stage. This study demonstrates that M. cephalus occupied diverse
environments and migrated among marine, brackish, and freshwater
habitats. More study is needed to determine whether the mullet in
the Tanshui River of Taiwan is a local population and its relationship
to the well-known offshore migratory population that migrates to
southwestern Taiwan to spawn in Dec.
Key words: Mullet, Freshwater fish, Otolith
elemental composition, Migratory environmental history.
*Correspondence: Tel and Fax: 886-2-23639570.
E-mail:wnt@ntu.edu.tw
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