Serving Northern St. Louis County, Minnesota

The waiting game

After a quick end to egg-stripping, it’s incubation time at Pike River Hatchery

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PIKE RIVER— A strong walleye run and a lower-than-average egg quota this year allowed Tower area DNR fisheries staff to wrap up egg-stripping operations in just four days. Hatchery manager Jeff Eibler couldn’t say whether that’s the shortest time for egg-stripping ever at the hatchery here, but it’s the shortest since he’s been in charge at the facility.

“We put in our nets on the seventh of April, starting egg stripping on the twelfth and were done by afternoon on the fifteenth,” he said.

This year, a low quota of just 708 quarts of eggs probably helped shave at least a day off the operations. According to Eibler, the quotas are determined based on the cumulative requirements of lake management plans throughout the state. “Those numbers just happened to be down this year,” he said.

With the egg-stripping completed, it’s incubation time at the hatchery and that means the facility must be staffed 24 hours a day until the eggs hatch, which Eibler expects to happen the week before fishing opener. Hatching time creates its own set of logistical concerns, since the DNR staff tries to get the young fry to their designated lakes within a day, or two at the latest. That gives the young walleye a longer period to transition from relying on their small yolk sacs to feeding on zooplankton, which will remain their primary food source for their first few months. The young fry can only go about 3-5 days without finding food, so the quicker they make it to their destination, the better their chances of survival.

This year, said Eibler, the short window for egg-stripping means the eggs will hatch pretty much all at once, which will mean a hectic few days as fisheries staff work to get the roughly 20 million fry to their various destinations. That’s not so unusual for the fisheries staff. Their hatchery operations involve intense activity during the egg-stripping phase, lots of waiting and monitoring while the eggs incubate, and a mad rush at the end to get all the fry distributed.

Just over a third of the fry are destined for lakes in the Tower work area, with Vermilion slated to receive 5 million, or about a quarter of the total harvest. Bear Island and Jeannette lakes are slated to receive 900,000 and 600,000 respectively, while Low and Clear lakes are scheduled to receive 300,000 and 250,000 respectively. Stuart Lake is slated to receive 240,000 fry, while Bear Head Lake is scheduled to receive 175,000.

Lake Saganaga will be the largest recipient outside of Vermilion, with the big border lake set to receive 4.5 million fry. Another 5.9 million will be distributed to lakes in the Grand Rapids work area.

For now, all those potential fry are still in egg form, under the watchful eyes of Eibler and other fisheries staff. It’s not all watching, of course. According to Eibler, the hatchery crew works steadily to separate out the unfertilized eggs that inevitably wind up in the incubating jars. Those “dead” eggs tend to develop a fungal growth that can kill the fertilized eggs if it gets out of control. The unfertilized eggs appear white and are more buoyant than the living eggs, so they tend to float to the top of the jars where staff can painstakingly remove them. With as many as 250,000 eggs in a jar, hatchery staff can end up having to remove hundreds if not thousands of unfertilized eggs from every jar.

While three-quarters of this year’s fry won’t make it back to Lake Vermilion, that’s still much more than the lake would receive without the presence of the hatchery according to Eibler. “Our hatch rate at Pike River averages about 75-80 percent,” noted Eibler. “Mother Nature is about 2-3 percent at best. So, in most years we are returning more fry to Lake Vermilion than would have hatched naturally from all the eggs we take.”

At the same time, Eibler notes, it’s not clear how much Vermilion actually benefits from the stocking from Pike River. “We are finding in lakes with adequate natural reproduction, like Vermilion, that additions of stocked walleye fry generally are insignificant at best and in some cases can actually reduce overall survival by increasing the demand for the limited food resources out there.”

That said, don’t look for the DNR to change the practice anytime soon, given that many in the public still seem to view the hatchery operations as somehow robbing Vermilion’s reproductive potential. “As you know, some folks get pretty excited about where all the ‘Lake Vermilion’ walleye eggs are going,” said Eibler.

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