Zoological Studies

Vol. 45 No. 2, 2006

Population Genetic Structure of the Swordfish, Xiphias gladius (Linnaeus, 1758), in the Indian Ocean and West Pacific Inferred from the Complete DNA Sequence of the Mitochondrial Control Region

Ching-Ping Lu1, Chaolun Allen Chen1,2, Cho-Fat Hui3, Tzong-Der Tzeng4, and Shean-Ya Yeh1,*

1Institute of Oceanography, National Taiwan University, Taipei, Taiwan 106
2Research Center for Biodiversity, Academia Sinica, Nankang, Taipei, Taiwan 115
3Institute of Cellular and Organismic Biology, Academia Sinica, Nankang, Taipei, Taiwan 115
4College of Liberal Education, Shu-Te University, Yen-Chiao, Kaohsiung, Taiwan 824

Ching-Ping Lu, Chaolun Allen Chen, Cho-Fat Hui, Tzong-Der Tzeng, and Shean-Ya Yeh (2006) The population genetic structure of the swordfish, Xiphias gladius, was studied using tissue samples collected from the Indian Ocean and West Pacific between 1999 and 2003 by Taiwanese longliners. In total, 175 individuals comprising 9 sampled units (2 units from the Pacific Ocean and 7 from the Indian Ocean) were surveyed using the complete DNA sequence of the mitochondrial control region (841 bp in length), which yielded a total of 142 haplotypes with a mean haplotypic diversity (h) of 0.9967 and nucleotide diversity of (π) of 0.01476 0.00046. Significant population subdivisions detected by F-statistics (Fst) and analysis of molecular variance (AMOVA) indicated that samples drawn from the waters off northern Madagascar and the Bay of Bengal were 2 distinct groups compared to the other populations from the Indian Ocean and West Pacific. In concordance with previous studies indicating the worldwide swordfish population's genetic structure, our study further suggests that the stock structure of swordfish in the Indo-Pacific region can be summarized into the following groups: an area off northern Madagascar, the Bay of Bengal, and the rest of the Indian Ocean and western Pacific, thus providing important information for management units of swordfish fisheries in the Indo-Pacific region.

Key words: Swordfish, Population genetic structure, Mitochondrial control region, Fishery management, Indian Ocean.

*Correspondence: Tel: 886-2-23637753. Fax: 886-2-23661197. E-mail: sheanya@ntu.edu.tw