Forensic geochemistry identifies the illegal introduction of Walleye into Lake Cascade, Idaho

The illegal introduction of fish species can disrupt ecosystems, collapse food webs, and undermine recreational fishing opportunities. Determining whether introduced fish are locally reproducing is important for resource managers. Here, we used the geochemical analysis of otoliths to investigate the potential illegal introduction of a Walleye Sander vitreus caught in 2022, in Lake Cascade, Idaho. Lake Cascade is known for its recreational Yellow Perch Perca flavescens fishery and has no documented resident population of Walleye.