Genoa National Fish Hatchery Interns Brandon Keesler and Ashley Umberger. - FWS photo

A construction worker shows the amount of dredge removed from the bottom of the hatchery ponds during the winter of 2003. This removal altered the pond water volume information which was used for decades. - FWS photo

In July and August of 2006, Genoa NFH interns Brandon Keesler and Ashley Umberger began surveying hatchery ponds in order to develop new water volume values. All nine of the renovated ponds were able to be completed over summer. The new water volume values will be a great asset in determining safe and efficient fertilization and treatment levels.

Walleye, largemouth bass, and smallmouth bass are three of the many species of fish reared at the Genoa National Fish Hatchery (NFH). These fish are integral in the propagation of endangered mussels such as the Higgins eye pearly mussel, as well as fulfilling commitments for fishery management requests throughout the Midwest.

Each of these species requires the use of the hatchery's outdoor rearing ponds, ranging in size from a half acre to 34 acres. Pond management during the growing season is critical for their survival and harvest.

Throughout the season, the nitrogen and phosphorus levels in the ponds need to be adjusted in order to promote phytoplankton and zooplankton communities which are beneficial as forage for young fish.

By taking water samples weekly, biologists can calculate the amount of inorganic nitrogen and phosphorus needed to add to the pond in order to attain a favorable ratio. However, the amount of fertilizer added is dependent on the water capacity of the pond.

Unfortunately, the last time the water volume of the ponds was calculated was decades ago. Since then, many of the ponds have been dredged and revamped, creating unknown pond volumes.