The lake sturgeon Acipenser fulvescens is targeted for rehabilitation across its range, but many questions remain about its movement patterns and habitat use beyond spawning migrations. An understanding of movements not related to spawning is crucial to understanding the life history of this threatened species and may play a key role in its recovery. To study movements and habitat use of the Muskegon River system by adult lake sturgeon, we tagged a total of 21 individuals with acoustic (i.e., emit a pulse of sound unique to that fish) transmitters and followed their movements using passive tracking methods (i.e., stationary receivers that detect the sounds emitted from acoustic transmitters). We have been following their movements since 2011 and plan to continue this project until the end of 2016. Our specific research objectives were to: 1) determine whether adult lake sturgeon are using the Muskegon River system (i.e., both the Muskegon River and Muskegon Lake) at periods outside the spring spawning season and whether primary residency (i.e., greater than 183 days/year) is occurring in Muskegon Lake or the Muskegon River, 2) determine the time (in days) that adult lake sturgeon remain in both Muskegon Lake and the Muskegon River (i.e., system residency) and the time (in days) individuals occupy the Muskegon River during spawning (i.e., river residency), and 3) characterize the spatial distribution (i.e., location in the river system) of spawning lake sturgeon in the Muskegon River with respect to river temperature, discharge, and calendar day. Our preliminary results suggest adult lake sturgeon are using the Muskegon River system extensively, some individuals are exhibiting primary residence, adults occupy the system during non-reproductive periods of the year, and their use appears to be independent of spawning activity in a given year.
Kregg Smith, Michigan Department of Natural Resources, Fisheries Division