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

Humans can radically alter aquatic ecosystems directly and indirectly. Fragmentation of river systems via the construction of dams affects the ability of migratory fish to move throughout a system and can hamper their ability to spawn. Overexploitation of fish stocks, especially when they congregate below dams, can result in recruitment overfishing where harvest exceeds the ability of a stock to replenish its numbers. Restoration of fisheries should focus on the anthropogenic influences that preceded their decline. Sauger Sander canadense in the tailwaters of several Tennessee impoundments represent the largest percid fisheries in the southeast USA. However, declining Sauger populations have been evident since historical spawning migrations were blocked by dams and little is known about current spawning areas in the Cumberland River. Additionally, Sauger were seasonally vulnerable to anglers in tailwaters and it is important to evaluate the population-level effects of catch-and-release (CR) mortality. The objectives of this research were to (1) describe the spawning migration of Saugers in the Cumberland River, and (2) estimate the instantaneous rate of CR and harvest mortality. To assess spawning movements, Saugers were implanted with radio transmitters in January2014and tracked weekly throughout the spawning season. To estimate the instantaneous mortality rate associated with CR fishing, Saugers implanted with radio transmitters were also tagged with an external high-reward ($100) tag and the reporting rate was assumed to be 100%. Telemetry relocations in conjunction with tag-return data allowed for the estimation of catch rates, release rates, and CR mortality for released fish. The monthly instantaneous mortality rate (Z) was 0.11, which represented one natural mortality, one harvest mortality, and two fish that died of CR mortality. Therefore, monthly M = 0.03, F_h= 0.04, and F_cr= 0.04. The weekly instantaneous emigration rate was 0.02 and their movements downstream and out of the tailwater began after water reached 10°C.