FIGURE 4 Between-year correlations of water temperature (a) and water level (b). Time windows are relative to the arrival timings of the same Sakhalin taimen individuals at tributary sites during MS2 in 2018 and 2019. PIT, passive integrated transponder.
Mean upstream swimming speed was 1.98 km day–1 for females and 2.90 km day–1 for males, which was not significantly different between sexes. However, downstream swimming speed for females (5.68 km day–1) was more than double that of males (2.63 km day–1) (t -test,P < 0.05). Travel time by the upstream migrants from the river mouth to the mid-point of tributary sites was estimated to be 12.2 days (95% CI: 4.2–35.6 days) for females (Fig. 5) and 8.3 days (95% CI: 1.9–36.1 days) for males.