Genetic Diversity and Structure of Cultured Broodfish of Tiger Pufferfish Takifugu rubripes Produced in Nagasaki Prefecture

Abstract

Anecdotally, it is considered that there are several populations for the cultured tiger pufferfish, Takifugu rubripes, in Japan; however, strict pedigree managements are not undertaken in hatcheries. To understand the genetic diversity and relationship among broodfish used in Nagasaki Prefecture, where the majority of aquaculture seedlings of this species are produced, genetic analysis was conducted using 12 microsatellite markers. DNA samples and pedigree information of each broodfish used for production in 2015 and 2016 were collected from private hatcheries. Samples from a total of 56 broodfish including 15 wild females were obtained. The artificially raised broodfish were grouped into three putative populations, Population A-C, based on pedigree records. The results of several genetic statistics showed significant genetic divergence from wild individuals among the populations. Population structure analysis revealed genetic independency of Population B and Population C, while it was implicated that Population A was occasionally interbred and crossbred with wild individuals, suggesting the susceptibility of population loss of Population A. Moreover, discordance in population assignments was observed between pedigree records and what inferred from molecular markers. These results indicated the necessity of pedigree managements with the aid of molecular markers for the sustainable use of these populations.