Measuring the historical conservation status of dragonet fishes in Tosa Bay, Southwestern Japan: ecological and genetic approach

Abstract

Dragonets are one of the dominant species in Tosa Bay, Southwestern Japan. However, until now, there is no baseline information on the conservation status of its species and populations. This study gathered genetic and ecological data and information to analyze and measure the historical conservation status of dragonets in the Bay. Quantitative values were converted into qualitative ranges to measures the conservation status of dragonet species. Eight dragonet species/populations were found to be in stable condition in the early 1990s, namely: Callionymus planus Ochiai, 1955; Callionymus lunatus Temminck and Schlegel, 1845; Callionymus curvicornis Valenciennes, 1837; Callionymus japonicus Houttuyn, 1782; Callionymus enneactis Bleeker, 1879; Synchiropus altivelis (Temminck and Schlegel, 1845); Repomucenus virgis (Jordan and Fowler, 1903); and Repomucenus huguenini Bleeker, 1858. Others were globally endangered and rare (Callionymus draconis Nakabo, 1977), locally highly vulnerable (Callionymus valenciennei Temminck and Schlegel, 1845; Callionymus beniteguri (Jordan and Snyder, 1900), locally vulnerable (Callionymus formosanus Fricke, 1981; Bathycallionymus kaianus (Günther, 1981)), and globally highly vulnerable (Callionymus sokonumeri Kamohara, 1936). The information gained in this study provided baseline knowledge on the historical species risk status of dragonets in Tosa Bay, which can be used as a basis for future studies. It also provided some scientifically-based options for managing biodiversity in a defined spatial management unit, which is applicable to e.g., marine protected areas, parks, bays, islands, lakes, etc.