TVA	River Neighbors
April 2006

New operating policy may benefit sportfish

TVA Fisheries Biologist Donny Lowery says the initial findings are encouraging. “It appears that TVA’s new reservoir operating policy may prove to be beneficial for reservoir sportfish communities.”

Back in 2004, TVA made a change in the way it operates the river system — moving from an approach that focused on achieving specific pool elevations to one that manages the flow of water through the system. Naturally, concerns arose during the course of the Reservoir Operations Study about how the decision to change water levels (including when levels would be raised or lowered, and by how much) would impact fish populations.

To address that issue, TVA commissioned Mississippi State University’s Dr. Steve Miranda, a renowned expert, to conduct an independent study. Miranda examined data on reservoir levels and sportfish populations over a 25-year period of record. He compared different water level regimes and studied those years that happened to effectively mirror the scenarios set forth in the ROS in great detail. In a fisheries statistical modeling report released last year, Miranda concluded that the kinds of gradual water level increases that take place under the new policy will likely result in favorable conditions for not just a few select species, but for reservoir sportfish communities as a whole.

The results of TVA’s 2005 spring sportfish survey seem to bear that out. Data generated from sampling conducted on all main-stem reservoirs reveal an across-the-board increase in catch rates — a good sign, according to Lowery. “There are many factors — including rain events prior to sampling and environmental conditions — that can influence catch rates. While one year’s data is not conclusive, we are cautiously optimistic about what these results mean. Only time will tell for sure, but it appears that water level variability may prove to be advantageous for a wide range of sportfish species.”