Relationship between the index of relative current direction to the AR (Dir) and number of eDNA copies (A) and predicted number of eDNA copies (B) of Trachurus japonicus. Open triangles, black circles, and gray squares of (A) show the number of eDNA copies at Dist 0.1, 0.2, and 0.4, respectively. The dotted, solid, and gray lines of (B) show the predicted number of eDNA copies at Dist 0.1, 0.2, and 0.4, respectively.