| Summary: | 碩士 === 國立臺灣大學 === 動物學研究研究所 === 95 === In Taiwanese neritic waters, blue mackerel (Scomber australasicus) and chub mackerel (S. japanicus) are found pelagic and migrating in shoals for feeding and spawning. These two species are important fishery resources for purse seiners and set-netters. For the purpose of fishery management and resource conservation, it is essential to discriminate two species and study their intra-population structures. There are a few studies related to the population structure of S. australasicus, and much fewer for S. japonicus. As a whole, the stock status of blue and chub mackerels in the hydrographic region of Taiwan is still far from comprehensive for management purpose.
In this study, my objectives are 1) to clarify inter-specific relationship of S. australasicus and S. japonicus, and 2) to explore intra-species structures in different hydrographic regions. Statistical analysis on morphometric measurements and RFLP-PCR analysis on the complete sequence of cytochrome b gene (cyt-b) were used to provide a quick, convenient and precise method to identify S. australasicus and S. japonicus. Morphometric measurements and microsatellite polymorphisms were used to study population differences among hydrographic regions.
The findings indicated the lack of clear-cut resolution in morphometric analysis for species discrimination and stock structure identification. Nonetheless, RFLP-PCR analysis based on cyt-b on can be an effective agent for species identification. Analysis of population structure based on microsatellite polymorphism revealed that two stocks of S. australasicus off Taiwan should be considered – one located in the northern water and the other in the southern. On the other hand, one unit stock of S. japonicus is suggested for management purpose.
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