Basin-scale spatiotemporal distribution of ayu Plecoglossus altivelis and its relationship with water temperature from summer growth to autumn spawning periods

Abstract As climate warming progresses, it becomes necessary to study the effects of water temperature on basin-scale dynamic distribution riverine fish. This examined spatiotemporal Plecoglossus altivelis using environmental DNA approach and its relationship with from summer growth autumn spawning periods in Nagara River basin, central Japan. The overall results P. were consistent known life history: a wide-range basin during aggregation middle mainstem autumn. Additionally, this found three intriguing patterns depending temperature. During (August), warmest period, was distributed upper mainstem, one tributary, downstream tributary confluences relation relatively colder (< 25 °C). early (September–early October), spread widely without constraint limit late (late October–November), steadily aggregated because migration for at temperatures below 20 °C. suggests importance river connectivity suitable habitats freshwater stages, tributaries as habitats, cooling mid-summer.