Migration and philopatry are important components of the life history strategies of many fish species. Migration trajectories and the extent of philopatry of native fish species in western Lake Erie were explored using naturally occurring trace elemental markers in fish earbones (otoliths). Some naturally occurring trace elements such as strontium and barium are incorporated in otoliths such that otolith chemistry reflects water chemistry. Therefore, fish movements between water masses with different chemistries can be inferred by changes in trace element otolith chemistry. To investigate the potential for using otolith chemistry to identify fish migrations in western Lake Erie, a controlled field enclosure experiment was conducted to identify site-specific otolith chemistry signatures. Juvenile yellow perch (Perca flavescens) were placed in field enclosures at multiple locations in the western basin of Lake Erie. Following the experimental trial, site-specific otolith chemistry signatures were assessed using Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICPMS). Results of this study indicate that the site-specific otolith chemistry signature from enclosures located in the Sandusky Bay and likely the Maumee Bay were unique from all other enclosure sites. Furthermore, site-specific otolith chemistry signatures from the offshore regions of western Lake Erie did not differ. A synoptic survey of trace elemental water chemistry supported the trends observed in otolith chemistry.
The unique site-specific otolith chemistry signature of Sandusky Bay provided a unique opportunity to assess the extent of philopatry of white bass (Morone chrysops). This native fish species undergoes spawning migrations into the Sandusky Bay and River from mixed offshore populations in western Lake Erie. Therefore, if spawning white bass collected in the Sandusky River are philopatric, then otolith chemistry will reflect the characteristic Sandusky River otolith signature. Results of this study suggest that 73% of the white bass population was philopatric to the Sandusky River spawning site, suggesting that the overall population may exist as multiple spawning subpopulations linked by non-philopatric individuals. This is the first observation of philopatry in a naturally reproducing, iteroparous fish species in the Great Lakes.