Figure 1

Schematic diagram of location of the cascade reservoirs (a) (Created by ArcGIS 10.5, www.esri.com), the trout production scale from 2009 to 2017 (b), and sampling points in the upstream Yellow River from LYR to JSR (c) (Created by ArcGIS 10.5, www.esri.com; Google Earth 7.3.3.7699, www.google.com/earth/). Solid red and hollow yellow circles indicated sampling points in CAA, with solid red circles indicating sampling points inside the cage groups, and hollow yellow circles indicating sampling points upstream or downstream the cages. Solid red circles also indicated where the trout cages groups located in UYR. Solid black triangle indicated sampling points in NAA.