Otolith microchemistry as a stock identification tool for freshwater fishes: testing its limits in Lake Erie

We evaluated otolith chemistry as a tool for identifying natal origins of potamodromous fishes using historical Lake Erie water chemistry (1983–2001) and yellow perch ( Perca flavescens ) otolith elemental composition (1994–1996) data. Lake Erie’s tributaries had stream-specific chemical signatures that were temporally stable. Correspondingly, the otolith microelemental composition of larvae collected from tributary embayments (Sandusky and Maumee bays) was shown to be geographically distinct and the use of known-origin juveniles showed that larval otolith microelemental signatures could be used to accurately identify natal origins and indicate fish movement. Discrimination between offshore spawning locations was relatively difficult, however, indicating limitations to working in systems that are dominated by flow from a single large river (i.e., Detroit River). Interannual variability in otolith microelemental signatures was high such that larvae from one year could not reliably classify natal location of larvae in another year. Development of an annual library of site-specific signatures and exploration of complementary ways to discriminate natal origins would improve the use of otolith microchemistry as a fishery management tool in freshwater systems.