Zoological Studies

Vol. 49 No. 2, 2010

Morphological and Molecular Analyses Reveal Separations among Spatiotemporal Populations of Anchovy (Engraulis japonicus) in the Southern East China Sea

Chih-Shin Chen1, Chih-Hsiang Tzeng2, and Tai-Sheng Chiu2,*

1Institute of Marine Affairs and Resource Management, National Taiwan Ocean University, Keelung 20224, Taiwan
2Institute of Zoology, Department of Life Science, National Taiwan University, Taipei 106, Taiwan

Chih-Shin Chen, Chih-Hsiang Tzeng, and Tai-Sheng Chiu (2010) Coastal and oceanic populations of Japanese anchovy (Engraulis japonicus) occur in the southern East China Sea.  The distributions of the larval stages of these populations provide a bases for subdividing anchovy into 3 spatiotemporal stocks for the management of local Taiwanese fisheries: spring coastal (sprW) and oceanic (sprE) stocks respectively in the western and eastern seas of Taiwan, and an autumn stock (autE) in Ilan Bay, northeastern Taiwan.  Using larval morphological analyses to evaluate population similarities, we found subtle differences between the sprE and sprW geographic stocks, but strong intra-geographic differences between sprE and autE seasonal stocks.  Molecular analyses, based on fragments of 740 bp (positions 200-939) of the mitochondrial DNA cytochrome b gene, revealed a substantial amount of genetic variations among populations.  Analysis of molecular variance indicated significant differences among stocks, primarily due to the sympatric contrast between sprE and autE (FST = 0.073, p < 0.001), rather than due to geographic subdivisions, such as sprE vs. sprW (FST = 0.039) or sprW vs. autE (FST = 0.007).  These results indicate the presence of a unique oceanic stock in eastern Taiwan in spring that is separated from the other populations.  This spatiotemporal heterogeneity suggests a dynamic state of larval recruitment along the coast of northern Taiwan.  We propose a dispersal route for larval anchovy from the Taiwan Strait to the northern coast, or active migration by adult anchovies in accordance with oceanographic patterns in the southern East China Sea.

Key words: Anchovy, Morphometry, Mitochondrial DNA, Stock, Cohort migration.

*Correspondence: Tel: 886-2-33662448.  Fax: 886-2-23634014.   E-mail:tschiu@ntu.edu.tw