Spawning season a delicate balance

An unfertilized fish egg sitting in a nest at Lake Hartwell was having trouble remembering what he was doing there … then it spawned on him.

Although today is April Fools’ Day, this time of year is no laughing matter for largemouth bass that live in sub-basins along the Savannah River.

Each spring, male fish build nests in shallow water by swinging their tails back and forth to create saucer-like depressions on the bottom, according to James Sykes, a fisheries biologist for the U.S. Army Corps of Engineers, Savannah District.

“If the water is clear enough, you can actually see the fish spawning,” Sykes said.

After establishing the nest, males attract females, who essentially lay eggs and swim away, leaving the males to protect the fertilized eggs.

Though the process seems straight-forward, it can be a harrowing experience for the males, who are vulnerable to predators from above (birds) and below (other fish) while they guard the eggs in the shallow water.

Far from the life-and-death action, district water managers also play a part during spawning season.

“The goal is to try to keep the pools as flat as possible,” said Jason Lavecchia, a water manager for U.S. Army Corps of Engineers, Savannah District. “It’s a challenge.”

During the four- to six-week spawning season, water managers monitor inflow and outflow, and strive to keep reservoir levels from fluctuating more than one half foot up or down, Lavecchia said.

This stability is critical for the success of the largemouth bass, which are the primary predators and have a considerable role in maintaining a balance in fish populations.

If water levels fall too quickly, males will abandon the nest, which makes the eggs vulnerable to predators, Sykes said.

However, it’s not all about the fish; in keeping with the Corps’ overall mission, biologists and water managers must balance the needs of local industry and citizens while protecting wildlife like the largemouth bass.

“We try to end the season as quickly as we feel practical … when we feel like most of the fish have spawned,” said Sykes. “It makes the [the water managers’] job harder, but it’s the most important thing we do for fisheries management.”

The 2015 spawning season began March 28 and is expected to last until late April or early May, Sykes said.

~ By Jeremy S. Buddemeier, public affairs specialist

About US Army Corps of Engineers Savannah District

The U.S. Army Corps of Engineers Savannah District oversees a multi-million dollar military construction program at 11 Army and Air Force installations in Georgia and North Carolina. We also manage water resources across the Coastal Georgia region, including maintenance dredging of the Savannah and Brunswick harbors; operation of three hydroelectric dams and reservoirs along the upper Savannah River; and administration of an extensive stream and wetland permitting and mitigation program within the state of Georgia. Follow us on Twitter @SavannahCorps and on Facebook.com/SavannahCorps
This entry was posted in Fish and Wildlife, Recreation, Studies, Water Management, Water Quality/Water Supply and tagged , , , , , , , , , . Bookmark the permalink.
  • yu nah ee tah

    Do the pine trees, mostly now drowned out, that sprouted in the lake bed down to about elevation 328′ provide cover for the young fish?

    OK
    Dumb question…