Mechanisms underlying natural variation in otolith elemental fingerprints of larval Lake Whitefish

Fish otolith elemental composition is used to infer natal origins and early life histories, but the relative roles of environmental exposure versus maternal influences remain uncertain for many species. We examined otolith elemental fingerprints of larval Lake Whitefish ( Coregonus clupeaformis) in Green Bay, Lake Michigan, finding two distinct geochemical groupings among wild-caught larvae. To identify mechanisms generating this variation, we conducted a reciprocal transplant experiment testing whether incubation environment drives larval otolith signatures. Larval signatures differed primarily by maternal spawning origin, while incubation environment contributed minimally. Classification analyses showed high assignment success to maternal source, with most misclassification among groups sharing maternal origin. These results indicate that maternally associated chemical signatures dominate larval otolith fingerprints through early development, complicating interpretation of larval otolith chemistry as a “natal environment” signal. Our findings clarify when larval signatures likely reflect maternal provenance versus environmental exposure and highlight the need for additional reference collections and temporal validation to strengthen natal assignment frameworks in the Great Lakes.