Determining Location from Pop-up Satellite Archival Transmitters When Earth Main Field Geomagnetic Data Is Insufficient: A Case Study with Lake Sturgeon in Eastern Lake Erie

Satellite telemetry has been employed in the study of fish migratory behavior for several decades. Early efforts of this technology relied solely on light-based data to determine longitude and latitude. However, advances in technology now incorporate magnetic field intensity (nT) data in addition to light-based data when determining latitude and longitude, respectively. While these data have proved useful in increasing position accuracy of migrations in open sea, they prove more challenging for a species such as Lake Sturgeon Acipenser fulvescens, in the Great Lakes where the main field intensity gradient is more subtle and dominated by magnetic anomalies. We employed an exploratory approach to assess Lake Sturgeon position from data collected by pop-up satellite archival tags (PSATs) within eastern Lake Erie and the upper Niagara River. Multiple metrics collected and archived by the PSATs, coupled with environmental data were used to determine the overall movement trajectory of an individual Lake Sturgeon during its deployment period.  While location resolution was low, this method did provide an overall description of Lake Sturgeon movement. Furthermore, these methods, while exploratory, may prove invaluable for researchers struggling to describe migration behavior of species equipped with PSATs in inshore waters or areas dominated by magnetic anomalies.