YANKTON, S.D. — A fish hatchery in South Dakota has seen big changes after the discovery of invasive zebra mussels in the Missouri River in recent years.

The Gavins Point Fish Hatchery focuses on sturgeon recovery, Missouri River paddlefish restoration and providing recreational sport fish like walleye and yellow perch.

“In 2003, they found the first suspect veliger (zebra mussel larvae) in Lews and Clark Lake,” said Jeff Powell of the hatchery. “That was when we set up a hazard analysis and critical control points plan. So, basically, since 2003, we have treated our lake water as positive for zebra mussels.”

The hatchery now has a slew of new precautions to ensure that the mussels would not contaminate any other bodies of water across the state. It also has a filter building at a total cost of about $700,000 to the South Dakota Fish and Wildlife Service, the Press and Dakotan (http://bit.ly/2uNBgms ) reported.

“We had to begin using filter socks on our ponds and drum filters on our sturgeon and endangered species buildings,” Powell said. “We also had to start using a chemical treatment on our fish prior to stocking to ensure that there are no zebra mussels in the water.”

While the new filtration system creates a barrier against aquatic invasive species, it has also stopped some of the hatchery’s natural food sources from entering the facility.

“It filters out all the zooplankton and some of the phytoplankton,” Powell said. “That has caused a little shift in our fertilization rates because we don’t get that larger amount of plankton. It puts us about a week behind, so we have to be a week ahead of where we used to be when filling up our ponds.”


Information from: Yankton Press and Dakotan, http://www.yankton.net/