Abstract
Overuse of natural resources by humans is a major threat to biodiversity. Overuse often involves species of economic or esthetic value, and fish are a typical example for a group that is exploited both for economic reasons (for human consumption) and for esthetic reasons (e.g. by aquarists). Pseudorhodeus tanago (Tanaka, 1909) (formerly known as Tanakia tanago) is a small colorful but legally protected (fishing, keeping and transfer are banned) bitterling fish distributed around Tokyo, Japan. Whereas it is critically endangered and more and more habitat loss has occurred, at least four stocks have been newly found during the last decade. To explore whether emergence of these newly found habitats is a consequence of incomplete survey, we genotyped mitochondrial cytochrome b sequence of P. tanago from 17 localities and an illegal home aquarium. Populations known by the past extensive survey (13 localities) showed geographically structured population genetic characteristics. Population-specific haplotypes were common indicating past divergence and bottleneck events. Four (north, {center + west}, south_1, south_2) or five (north, center, west, south_1, south_2) geographic groups were detectable as for these known localities. On the other hand, newly found stocks were polymorphic and showed identical haplotypes from distant known localities. If we assume historical basis of distribution and genetic characteristics of these newly found stocks, it must be a series of unlikely geological events and haplotype sorting. We discuss potential issues posed by these questionable stocks.
Highlights
Overuse of organisms by hunting or fishing for trade or esthetic purposes is one of the biggest threats to biodiversity
Pseudorhodeus tanago from 13 known localities collected from 1993 through 2013 (55 individuals), four newly found stocks collected from 2010 through 2014 (22 individuals), and three individuals seized from an illegal home aquarium were materials of this research (Table 1, Fig. 1b)
The low sequence diversity of Pseudorhodeus tanago represented as monotypy in most known localities (11/13) conformed to their habitat characteristics (Table 2)
Summary
Overuse of organisms by hunting or fishing for trade or esthetic purposes is one of the biggest threats to biodiversity. Controlling these activities is fundamental for ensuring the persistence of endangered organisms, those that have traits attractive to humans. The red list of Japanese brackish and freshwater fish (Ministry of the Environment, Japan 2015) acknowledges 39 species out of 168 of endangered and vulnerable categories have threats of overfishing in connection with home aquarium. Poaching and dumping of endangered and protected fish, if any, disturb conservation programs and policy making and threat that species
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