Musky are confused by the weather, and so is the DNR
By Dave Orrick – Pioneer Press (4/10/12)

It got warm, then hot, and now it's chilly. If that threw your spring wardrobe out of whack, imagine what it's done for spawning muskellunge.

The warm water temperatures in central and southern Minnesota lakes brought the males in shallow, ready for some action. Many have been stood up by females not quite in the mood yet, their eggs not ready, while other females inexplicably seemed to have dumped their eggs.

The dating scene in the walleye world isn't a whole lot different: There's a lot more flirtation than actual spawning.

The fish are confused by the weather, and so are fisheries biologists, who are trying to gather eggs and sperm to hatch fish to be stocked statewide.

"I've talked to everyone I can think of, guys who have been doing this for 30 years, and all these guys are scratching their heads this year," said Neil Vanderbosch, who coordinates the annual egg-taking program for the Minnesota Department of Natural Resources. "Nobody has much experience with this kind of weather."

Vanderbosch said people from private hatcheries and Iowa have told him they're having similar experiences, and it looks like it will be a challenge for many hatcheries to gather enough eggs to meet their quotas. The confusion lies in the balance of temperature and the length of day. Generally, fish rely on both to spawn.

Case Study:

Lake Rebecca in western Hennepin County provides an example of how the unseasonably warm March threw a wrench into things.

Rebacca is a brood stock lake that serves as the source of eggs for muskies to be hatched and stocked statewide. (The fish are originally from Leech Lake, and muskies directly from Leech are stocked into Rebecca every four years.)

Muskies usually begin spawning when shallow waters reach 54 degrees, so the DNR closely watches the temperature and sets nets when the temp hits 53. Since 1988, the earliest that ever had happened was April 12. This year, it happened Tuesday, April 3.

Not wanting to miss their opportunity, BJ Bauer, a fisheries specialist for the DNR's west metro area, set out nets the next day, even though the length of daylight was nowhere near what it typically would be for spawning.

The nets caught plenty of males, including a 45-inch stallion that has proved to be geyser of semen. But as of Tuesday, April 10, only six females had been netted, and only three of them have yielded eggs, Bauer said.

"We've still got a long way to go," Bauer said Tuesday. The DNR's goal is to reap at least 800,000 eggs; they're at about 100,000. Strangely, some of the females appeared to have released their eggs - a phenomenon egg collectors also are seeing in northern pike and walleye throughout the state.

"It makes no sense."

BJ Bauer, fisheries specialist with the Minnesota Department of Natural Resources, releases shows a vile of ovarian fluid collected from a female Muskie netted on Rebecca Lake in western Hennepin County near Independence during an annual egg and sperm gathering for stocking April 6, 2012. The fluid will be tested for diseases. (Pioneer Press: Dave Orrick) at all," Vanderbosch said. At the same time, "green" females, whose eggs aren't yet developed, are being netted.

EGGS WANTED

Vanderbosch is guardedly optimistic that the DNR won't come up short when the season is over. The agency will gather enough eggs to raise enough fish in hatcheries to stock enough fry and fingerlings to supply anglers with enough fish to be caught in a few years. Most Minnesota lakes are stocked by natural reproduction of game fish, but many lakes popular among anglers are stocked with hatchery-raised fish, a process funded by fishing license sales. "We'll get our eggs, eventually," Vanderbosch said. "But a lot of the guys are getting tired."

Crews that collect fish and eggs are a combination of DNR staff and volunteers who spend a lot of time waist-deep in water, up to their necks in fish slime and even slurping semen on occasion. (The process for extracting milt, or sperm, from a male muskie involves inserting a tube into an orifice and sucking to create a siphon, much like the old-school way of pulling gas out of a fuel tank.) Because the process involves netting quantities of prized game fish and keeping them penned up overnight, many egg-gathering locations are staffed 24 hours to prevent thievery.

The DNR's egg-gathering program has backup plans, and Vanderbosch said he expects that the backup Muskie lake - Elk Lake near Lake Itasca - likely will have to be tapped.

The sporadic spawning season might lead to a low year for fish that hatch naturally, because early males might tire and leave the area before females drop their eggs. But Dirk Peterson, chief of the DNR's Fisheries Division, said fishermen need not necessarily worry. By the time the fish are grown, they might be plentiful. "Sometimes low natural reproduction can result in lower competition, which can lead to a healthy year class," Peterson said.