Walleyes spawn once a year using water temperature and photoperiod (length of day) as cues to spawn. DNR crews captured 1,910 adult female walleyes at East Okoboji, Rathbun, Spirit, and Storm lakes, as well as the Mississippi River.
Crews began netting operations on Rathbun Lake on April 5, while gillnetting at Storm Lake started on April 7. Operations at East Okoboji and Spirit lakes began the night of April 9. 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.
“The 2025 walleye netting season represents another highly productive and very efficient broodstock collection season,” said Jay Rudacille, DNR Warm and Coolwater Fish Culture supervisor. “This year is one of the shortest, if not the shortest, netting seasons in our walleye gillnetting history as enough females were collected to meet our egg quota in eight combined nights of netting operations at four locations across Iowa.”
A quick netting season led to a brief spawning season as well. “Typically, it takes five to seven days of spawning to collect enough eggs to meet fry production requests, but this year, only three days were needed,” said Kim Hawkins, Hatchery Manager at Spirit Lake Fish Hatchery. “During this time, Spirit Lake Hatchery staff spawned more than 540 female walleyes, yielding about 560 quarts of eggs.”
Along with some walleye adults that stay at the hatchery all year long, netting crews collected enough walleyes to produce in excess of 682 quarts at the Rathbun Fish Hatchery. Crews at East Okoboji and Spirit lakes collected females that produced 562 quarts of walleye eggs now incubating at Spirit Lake Fish Hatchery. Storm Lake crews spawned enough females to produce 151 quarts of walleye eggs. The Storm Lake satellite hatchery transferred their eggs to the Rathbun and Spirit Lake fish hatcheries to be incubated and hatched.
“Our goal was to collect 1,324 quarts of walleye eggs to produce nearly 116 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 explains. “In total, 1,399 quarts of walleye eggs are currently hatching or are being incubated.”
“Walleye populations in our ‘broodstock lakes’ are in exceptionally good shape thanks to our district fisheries management teams who manage these lakes, as well as the walleye culture and stocking program of DNR coolwater hatcheries,” Rudacille stated.
“The walleye population in Rathbun Lake is at a 10-year high,” said Mark Flammang, District Fisheries Management biologist. “This is mostly due to very little precipitation in recent years which has resulted in good water quality and excellent survival of our stocked walleyes.”
Further evidence of the strength of walleye populations in lakes where broodstock are collected for spawning purposes is that over 1,800 walleyes were collected by just four crews in two nights of netting in Spirit Lake. “Mississippi River walleye populations are phenomenal and have been for some time. This population is naturally reproducing and self-sustaining and not dependent on annual stockings like the walleye populations in Iowa’s lakes and reservoirs,” Rudacille stated.
Efforts to produce 116 million walleye fry is a team effort with most DNR Fisheries employees having a role in the project. “Many employees work a night shift during this season to collect walleyes into the wee hours of the morning,” explains Rudacille. “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, IL, 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. This team worked collaboratively to produce 79 quarts of eggs from Mississippi River females that were transferred to Rathbun Fish Hatchery for incubation and hatch. Fry hatched from these eggs will be used in an important research project comparing their survival rate to fry produced from lake strain females.
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 32 public bodies of water and 10 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 million two-inch walleyes are expected to be stocked into lakes, rivers, and streams across Iowa this summer. Larger 6- 9-inch fingerlings (nearly 310,000) will be stocked in lakes later this fall.
With little natural reproduction in most Iowa lakes and rivers, Iowa’s walleye populations depend on stockings. Walleyes are stocked throughout Iowa into natural lakes, interior rivers, flood control reservoirs and selected larger man-made lakes.