Spatial Scale and Natal Influence on Spawning Site Fidelity in Northern Pike: Investigation Using Otolith Microchemistry Techniques

Reliance on wetlands for Northern Pike reproduction renders populations vulnerable to anthropogenic disturbance including habitat impairment and water level regulation.  While spawning site fidelity has been well documented with tagging studies, few have attempted to directly address natal site fidelity.  Integrated tagging and genetic studies in a Minnesota lake and the St. Lawrence River provide mixed evidence for natal site fidelity. Further, otolith microchemistry analysis did not support natal site fidelity in degraded Wisconsin waterways.  Otolith microchemistry analysis of Baltic Sea Northern Pike showed evidence of natal homing in only 50% of study streams, separated by >50 km.  Trace analysis of 3 St. Lawrence River tributary wetlands shows significant elemental differences among individual branches and associate bays.  Otolith microchemistry analysis could provide insight into the natal origin of spawning pike.  Two spatial scales will be investigated to examine the confounding influence of low dispersal on natal site distinction.   Comparison of tributary spawning sites separated by 10-20 km representing coarse scales, to branches in closer proximity (<100m) provide an opportunity for a fine-resolution analysis.  A more complete understanding of spawning site fidelity would enhance our mechanistic view of Northern Pike population structure and influence conservation and management of reproductive habitats.