Chang-En Chou1, Te-Yu Liao2, Hsueh-Wen Chang1, Shui-Kai Chang3. 1. Department of Biological Sciences, National Sun Yat-sen University, 70, Lien-hai Road, Kaohsiung 804, Taiwan. 2. Department of Oceanography, National Sun Yat-sen University, 70, Lien-hai Road, Kaohsiung 804, Taiwan. 3. Institute of Marine Affairs, National Sun Yat-sen University, 70, Lien-hai Road, Kaohsiung 804, Taiwan.
Abstract
BACKGROUND: Hirundichthys oxycephalus is an important flyingfish resource in eastern Taiwan and northwestern Japan. A substantial catch decline in Taiwan has caused serious concerns on stock status of the fish, prompting the government to impose a set of regulations on flyingfish egg fishery since 2008. However, the regulations were set in a precautionary manner, without considering the fundamental understanding of the population genetic structure. This study aims to investigate the population genetic structure of H. oxycephalus in the region based on mtDNA cytochrome oxidase I (COI) gene and to thus provide scientific information for sustainable management of theresource. RESULTS: Tissue samples (156) from six localities of eastern Taiwan and western Japan were collected, and 616 bpof mtDNA COI gene were sequenced. Seventy haplotypes were determined, and the haplotype diversity and nucleotide diversity were estimated as 0.93% and 0.57%, respectively. Results of various statistical analyses suggested that the genetic differentiations among the six localities were small and most variation occurred within populations, indicating a high gene flow in the region with undergoing population expansion. Although the study showed that the fishes were genetically divided into two groups, the support was low and the separation was not geologically evident. CONCLUSIONS: Thestudy revealed two groups of H.oxycephalus inthe northwestern Pacific Ocean. However, due to high gene flow, an association of either group to a spatial distribution was not observed, and so the two groups may be considered as one population. Thus, the results favored the conclusion that H. oxycephalus from eastern Taiwan and western Japan belong to the same population and, consequently, that the management unit of the current regulations only covering eastern Taiwan does not match the spatial structure of the population. Rather, the results suggest that joint efforts from countries within the population boundary are necessary to maintain a sustainable exploitation.
BACKGROUND:Hirundichthys oxycephalus is an important flyingfish resource in eastern Taiwan and northwestern Japan. A substantial catch decline in Taiwan has caused serious concerns on stock status of the fish, prompting the government to impose a set of regulations on flyingfish egg fishery since 2008. However, the regulations were set in a precautionary manner, without considering the fundamental understanding of the population genetic structure. This study aims to investigate the population genetic structure of H. oxycephalus in the region based on mtDNA cytochrome oxidase I (COI) gene and to thus provide scientific information for sustainable management of theresource. RESULTS: Tissue samples (156) from six localities of eastern Taiwan and western Japan were collected, and 616 bpof mtDNA COI gene were sequenced. Seventy haplotypes were determined, and the haplotype diversity and nucleotide diversity were estimated as 0.93% and 0.57%, respectively. Results of various statistical analyses suggested that the genetic differentiations among the six localities were small and most variation occurred within populations, indicating a high gene flow in the region with undergoing population expansion. Although the study showed that the fishes were genetically divided into two groups, the support was low and the separation was not geologically evident. CONCLUSIONS: Thestudy revealed two groups of H.oxycephalus inthe northwestern Pacific Ocean. However, due to high gene flow, an association of either group to a spatial distribution was not observed, and so the two groups may be considered as one population. Thus, the results favored the conclusion that H. oxycephalus from eastern Taiwan and western Japan belong to the same population and, consequently, that the management unit of the current regulations only covering eastern Taiwan does not match the spatial structure of the population. Rather, the results suggest that joint efforts from countries within the population boundary are necessary to maintain a sustainable exploitation.
Authors: Robert D Ward; Tyler S Zemlak; Bronwyn H Innes; Peter R Last; Paul D N Hebert Journal: Philos Trans R Soc Lond B Biol Sci Date: 2005-10-29 Impact factor: 6.237