Moravia, Iowa – The northern pike spawn is over in plenty of time to get ready for the walleyes. It hasn’t happened this way in a few years but thanks to Mother Nature, the fisheries staff will have enough time – and more importantly tank space – to prepare for the thousands of walleyes soon to be heading their way.
The DNR normally collects walleyes beginning in early April, but the warmer than normal winter and spring is making 2012 collection a bit less predictable.
Walleyes spawn when water temperature is in the middle 40s and the photoperiod (daylight) length is around the first week of April. The water temperature at Lake Rathbun is 51 degrees at the dam and 60.5 degrees at Bridgeview. Spirit Lake is around 52 degrees.
“Walleyes are a little confused right now. The water temperature has passed the point where they would normally spawn, but the photoperiod is not right,” said Joe Larscheid, chief of fisheries for the Iowa Department of Natural Resources. “We netted last night at Rathbun and found more than 50 percent of the females were ripe so we’ll net again there tonight and likely start going on Wednesday night.”
The Spirit Lake crew will set test nets on East Okoboji Lake Thursday night to collect enough females to determine how far they are progressing toward the spawn.
“Our goal is not to merely collect eggs, but to produce fry for stocking,” said Donna Muhm, hatchery manager at Spirit Lake. “Spawning fish before they are ready will not result in viable fry.”
Lake Rathbun and Spirit Lake are major suppliers of walleye eggs for the state, with some eggs coming from Storm Lake and Clear Lake. Fisheries crews need to collect more than 170 million walleye eggs to meet stocking requests.
The walleye collection takes place at night, using entanglement nets, called gillnets, set perpendicular to the shoreline in likely spawning areas.
Walleyes move in to shore in the evening and get hung up in the nets. Crews collect fish around 9 p.m., re-set the nets, and then make a second run 11 p.m. or midnight.