Biology, Management, and Protection of North American Sturgeon

Abstract

<em>Abstract.</em>—Lake sturgeon <em>Acipenser fulvescens</em> populations in the Great Lakes were drastically reduced in the late 1800s by commercial overfishing and habitat degradation. Although restoration efforts are underway, a lack of current information regarding the status of remaining populations has hindered recent rehabilitation efforts. The Manistee River is believed to support one of the largest remaining lake sturgeon populations in Lake Michigan. However little is known about the current status or population dynamics of this remnant stock. The main objectives of this study were to obtain annual spawning population estimates and to evaluate age and growth of the adult population. From April through June, 1999–2000, lake sturgeon were captured in the Manistee River using large mesh bottom-set gill nets. Population estimates were obtained using the Schnabel population estimator, and age was determined from cross-sections of pectoral fin ray samples. Back-calculations of length-at-age revealed that growth rates of Manistee River lake sturgeon were slightly higher than those obtained in previous studies of lake sturgeon populations inhabiting other similar river systems. Estimates of the spawning run were 106 in 1999 and 57 in 2000. Age analysis of captured fish, however, revealed that approximately one-half of the catch was composed of juveniles, suggesting that the actual number of spawning adults was probably less than 50 individuals in each year.