Otolith microchemistry to identify sources of larval yellow perch in a fluvial lake: an approach towards freshwater fish management

The study aims at determining which spawning sites are contributing to yellow perch (Perca flavescens) juveniles' recruitment in Lake Saint-Pierre (St. Lawrence River, Canada). We expect to highlight new management perspectives. Thus, we investigated both natal origin and connectivity processes for young of the year prior to their first winter. Otolith chemical composition was measured at larval and juvenile stages using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Five spawning sites were sampled and discriminated using a three-elemental model (manganese, barium, strontium). Results showed that (i) all within-lake sites contributed similarly to juvenile production and (ii) production results from both local recruitment and lake-wide connectivity processes. The study suggests fish management should include an overall evaluation of the lake-wide recruitment. Both local and widespread actions are required, depending on the level of connectivity in the lake, which plays a central role in shaping the spatial pattern of recruitment. Finally, otolith microchemistry proves to be an efficient tool for freshwater fish managers to evaluate both natal origin and connectivity in heterogeneous aquatic ecosystems.