Cooperative Fish and Wildlife Research Units Program: Tennessee
Education, Research and Technical Assistance for Managing Our Natural Resources

Minimum length limits were established in 1992 for sauger (Sander canadensis) populations in the Tennessee River to reduce exploitation and improve their size structure. The objectives of this study were to describe trends in stock characteristics since the early 1990s and assess the likelihood of overfishing in recent years. Otoliths were removed from saugers collected from late winter to early spring in 1993-1997 and 2008-2009 in Kentucky Lake and Watts Bar Lake, two mainstem reservoirs on the Tennessee River. Each fish was aged by examining its otoliths, yields were simulated using the Beverton-Holt yield per-recruit model, and spawning potential ratios were calculated to assess the likelihood of recruitment overfishing. Mean ages and mean total lengths (TL) did not exhibit any trends between 1993 and 2009 in Watts Bar Lake. No trend in mean ages was detected over time in Kentucky Lake but mean lengths increased ~ 3.2 mm/year. The Kentucky Lake sauger population in 2008-2009 did not exhibit signs of growth overfishing or recruitment overfishing under the previous minimum length limit of 356 mm TL. The Watts Bar Lake sauger population did not exhibit signs of growth overfishing under the current limit of 381 mm TL, but was susceptible to recruitment overfishing at high (> 40%) exploitation rates when natural mortality was low. Eliminating the size limits in either reservoir would increase the likelihood of both types of overfishing, but the extent of risk would depend on the level of exploitation and natural mortality in each reservoir.