The annual water management period for fish spawning officially began April 5 in the Savannah River Basin—and so far, conditions are favorable for a very productive spawn, said Jamie Sykes, fisheries biologist for the U.S. Army Corps of Engineers Savannah District.
According to Sykes, spawning season begins when surface water temperatures reach 65 degrees Fahrenheit at Hartwell, Russell and Thurmond lakes.
“We use 65 degrees as a starting point since that’s the preferred spawning temperature for largemouth bass, which is the most popular sport fish on our Savannah River reservoirs,” Sykes said. “But that temperature also falls within the spawning season for other species, so it benefits multiple species.”
During this period—which typically lasts between four and six weeks—water managers aim to maintain pool elevations with no more than a six inch drop in reservoir levels. Sykes said that a slight increase in pool elevation during spawning season is permissible, but drastic increases can be just as troublesome for spawning as rapid decreases.
“If we allow water to rise too high during spawning season, fish may spawn in those newly-flooded areas near the shoreline; but when the water recedes, fish will often abandon their nests and predators will overtake them,” Sykes said.
Outflows increased this week to maintain lake levels
Shortly after the spawning period began, the basin experienced a concentrated, heavy rainfall event April 7, which dumped 3 inches at Hartwell, 2.3 inches at Russell and 2.2 inches at Thurmond. That rainfall translates into additional “run-off” into the reservoirs, causing pool elevations to quickly rise.
To ensure minimal impact on critical fish spawning, our water managers have increased releases from the dams this week until we reach a target elevation of 660.5 feet above mean sea level (ft-msl) at Hartwell and 329.5 ft-msl at Thurmond.
Our water managers have revised the weekly declaration several times in the last few days in response to quickly-changing basin conditions. Daily outflows will change as basin conditions change, so be sure to check our water management website for the latest real-time data at http://water.sas.usace.army.mil. To view the latest declarations, click the “Declarations” button in the left menu.
Sykes predicts this spawning season will be very beneficial to the basin, but fishermen won’t reap the benefit until two or three years from now when the eggs become mature fish suitable for sport fishing.
“When the lake levels were down during the last drought, a lot of vegetation grew up along the shorelines,” Sykes said. “And now, all of that vegetation is flooded, so there is a tremendous amount of shoreline cover at Hartwell and Thurmond. That usually equates into a good spawning season.”
Sykes said shoreline cover is important since it provides protection from predators and provides a nursery area for small fish.
“This water level management during the spawning season is the single most important thing that the Corps can do to aid fisheries in our lakes,” Sykes said. “We don’t stock fish, we don’t set regulations—the states do that. But we do control the water. So it’s very beneficial to sustain fisheries at our reservoirs.”
~By Tracy Robillard, public affairs specialist