Population Status of Lake Sturgeon in the Muskegon River System, USA

The Muskegon River, a drowned river mouth system, is a Lake Michigan tributary that supports a remnant population of lake sturgeon (Acipenser fulvescens).  We have been working to assess the status of this population since 2008.  Adults were captured using both gill netting and boat electrofishing; and 24 of those individuals were ultrasonically tagged and their movements passively tracked.  Juveniles were captured using small mesh gill nets.  In fall 2013, we implemented random sampling in addition to fixed-site sampling for juvenile lake sturgeon.  We captured 108 unique adult lake sturgeon (range=103.5–191.0 cm TL) during this study.  Juvenile lake sturgeon were captured each year of the study (n=165; range=23.1 to 98.5 cm TL).  Age determination (n=181) indicates 27 year classes were represented in our catch (mean age=7.2).  Our results suggest: (1) the spawning run in the Muskegon River is small, (2) there is evidence of natural reproduction given the juvenile lake sturgeon captured in Muskegon Lake, (3) fall gillnetting at a fixed location (where juvenile lake sturgeon are known to inhabit) is more effective than random sampling for capturing more juveniles (t₁₀=4.20 P=0.002), and (4) seasonal usage of the Muskegon River system by adult lake sturgeon extends beyond annual spawning migrations.