Differentiating Resident from Migrant Lake Sturgeon in the Lower Niagara River

Little is known about the population status of lake sturgeon Acipenser fulvescens in the lower Niagara River. To help address this knowledge gap, we initiated a study investigating migration and habitat selection patterns of lake sturgeon in the lower Niagara River using fixed-station telemetry methods. To date, 60 lake sturgeon have been tagged with radio-telemetry transponders during spring of both 2011 (n = 30) and 2012 (n = 30). In October, 2011, an 8-receiver fixed-station radio-telemetry array was deployed along the lower Niagara River to continuously monitor radio tags. Through the summer of 2012, we gathered sufficient data to evaluate our study design, coverage area, and preliminary results. From October, 2011 through April, 2012, a large percentage of fish tagged during 2011 were observed in the river, and we observed some significant among-fish heterogeneity in occupancy pattern. However, more detailed inference was confounded by low observation rates. During tagging procedures in 2012, we identified sex and spawning stage of lake sturgeon during tag implant procedures. We then evaluated the use of site occupancy models and discrete choice habitat selection models to test for differences in lake sturgeon river usage by sex, spawning status, and other covariates both within spawning season and study-wide. Results from this analysis may be used to better estimate the proportion of resident lower Niagara River lake sturgeon versus migratory spawning adults and may help explain the distribution of age and size of lake sturgeon observed during spring surveys.