Fig. 6

Three-dimensional plots of the sampling location latitude (x), sampling day (y, 15 November 2016 = day 0), and the δ18Ootolith − δ18Owater (z) of Anguilla japonica glass eels. Note: the δ18Owater is set at +0.06‰. The regression plain obtained from the linear mixed model is shown as a green plain (pseudo r2 = 0.185, z = 0.0145x + 0.00254y − 1.30).