Walleyes spawn once a year using water temperature and photoperiod(length of day) as cues to spawn. DNR crews captured 3,318 adult female walleyes at East Okoboji, Rathbun, Spirit, Clear, and Storm lakes, as well as the Mississippi River.
Rathbun and Storm lakes began netting operations on April 4, while Clear, East Okoboji, and Spirit lakes started gill netting for walleyes on April 8. The last night of netting was April 10, but the spawning of fish continued as “green” females ripened in the hatchery until egg quotas were met.
“We entered this year’s walleye broodstock collection and spawning season with a little uneasiness due to the mild winter and unseasonably warm weather in the middle of March,“ said Jay Rudacille, DNR Warm and Coolwater Fish Culture supervisor. “But the 2024 season turned out to be exceptional with a quick season and overall efficient operation. Enough female walleyes were collected to meet our lofty egg quota in 14 combined nights of netting across operations at four locations across Iowa.”
Along with some walleye adults that stay at the hatchery all year long, netting crews collected enough walleyes to produce 701 quarts at Rathbun Fish Hatchery. Crews at East Okoboji and Spirit lakes collected females that produced 549 quarts of walleye eggs now incubating at Spirit Lake Fish Hatchery. Storm Lake crews spawned enough females to produce 448 quarts of walleye eggs, while efforts at Clear Lake produced 191 quarts of eggs. The Clear and Storm Lake satellite hatcheries transferred their eggs to the Rathbun and Spirit Lake Fish hatcheries to be incubated and hatched.
“Our goal was to collect 1,738 quarts of walleye eggs to produce nearly 155 million walleye fry (newly hatched fish) that we can stock in Iowa lakes or raise to a larger size in hatcheries before being released,” Rudacille said. “In total, 1,889 quarts of walleye eggs are currently hatching or are being incubated.”
“Walleye populations in our ‘broodstock lakes’ are very strong thanks to our district fisheries management teams who manage these lakes, as well as the walleye culture and stocking program of our three DNR coolwater hatcheries,” Rudacille said. “Mississippi River walleye populations are absolutely phenomenal. Naturally reproducing and self-sustaining, this population is not dependent on annual stockings like the walleye populations in Iowa’s lakes and reservoirs.”
Producing 155 million walleye fry is a team effort with most DNR fisheries employees intimately involved.
“Many employees work a night shift during this season to collect walleyes into the wee hours of the morning,” Rudacille said. “Several employees work at stations more than 100 miles from their homes and away from their families during collection efforts.”
Participation in the annual walleye broodstock collection and spawning operations extends outside of the Fisheries Bureau with employees from the DNR’s Law Enforcement and Parks bureaus. Entities outside of the DNR play an important role in this “once a year” operation. DNR staff from Fairport Fish Hatchery and the Bellevue Fisheries Station teamed up with staff from the fish hatchery associated with the Quad Cities Clean Energy Center just north of Cordova, Ill., as they have for several years. Personnel from DNR and the Quad Cities Fish Hatchery joined forces to collect broodstock and spawn fish to meet egg quotas for both facilities.
Iowa is one of the top producers of walleye fry in the United States, surpassed only by Minnesota in annual production. While some walleye eggs have already hatched, hatchery staff will keep a watchful eye over the remainder of the eggs during the 12-21 day incubation period. Walleye fry will be stocked into 35 public bodies of water and eight watershed rearing ponds. While the majority of walleyes are stocked as fry, some are cultured in Iowa DNR hatcheries and stocked at different sizes. More than 1.1 million two-inch walleyes are expected to be stocked into lakes, rivers, and streams across the state this summer. Nearly 330,000 6- to 9-inch fingerlings will be stocked in lakes later this fall.
With little natural reproduction in most Iowa lakes and rivers, Iowa’s walleye populations rely heavily upon stockings. Walleyes are stocked throughout Iowa into natural lakes, interior rivers, flood control reservoirs and selected larger man-made lakes.