Published April 05, 2011, 02:16 PM

Hooked on good fishing: Spirit Lake Fish Hatchery rears game fish for Iowa lakes

SPIRIT LAKE, Iowa — Several large aquariums filled with native fish lure thousands of visitors through the door of the Spirit Lake Fish Hatchery each year.

By: Julie Buntjer, Northland Outdoors

SPIRIT LAKE, Iowa — Several large aquariums filled with native fish lure thousands of visitors through the door of the Spirit Lake Fish Hatchery each year.

There, they can view everything from bass to bullheads and carp to short-nosed gar through large windows, and also see something they wouldn’t see in the wild — an albino catfish donated to the aquarium. It’s a definite hit with the youngsters, but then so are the tank of turtles, the aquariums of snakes, the dangling wildlife hides and assortment of mounts.

The real story, however, unfolds through the door and down a few steps, where the fisheries staff works to ensure the angler in us has a good day at the lake.

The first fish hatchery in Spirit Lake dates back to 1880, when the hope was that trout and whitefish, among others, could be reared and stocked into the Iowa Great Lakes — a chain that includes Big and Little Spirit lakes, East and West Okoboji lakes and several smaller bodies of water.

A new hatchery building was constructed in 1915 and expanded in 1927 before being torn down in 1963 to make room for the present structure, located on the south end of Big Spirit Lake. By the 1970s, concrete tanks were added in which to rear fish.

Already at that time, walleye had become the focus at the fish hatchery in Spirit Lake. One of eight located around the state of Iowa, the hatchery collects, spawns, incubates and raises walleye for stocking throughout the state. Northern pike and muskellunge are also reared at the facility.

Donna Muhm serves as hatchery manager, and says the reason the hatchery was established in Spirit Lake more than 130 years ago — it is the only fish hatchery in northwest Iowa — was because the state’s first fish commissioner hailed from the area.

Today, the fish hatchery serves as a source of predator fish — walleye, muskellunge and northern pike.

By the numbers

In a typical year, the Spirit Lake Fish Hatchery hatches about 100 million walleye fry, rears another half million 2-inch walleye and raises an additional 25,000 7-inch walleye inside its facility on the south side of Big Spirit Lake.

“We have two nursery lakes where we rear our 2-inch fish, and one of those lakes is used to rear walleye to about 6 inches,” said Muhm.

At the same time, the facility produces 5 to 6 million northern pike fry, 250,000 3-inch northern pike and about 100,000 muskellunge fry.

Of the three types of predator fish reared at the hatchery, the northern pike seems to be the most proficient at reproduction in the wild — still, the numbers aren’t great. Thanks to the fish hatchery, the average angler can enjoy some “pretty good fishing.”

All in a day’s work

Each April, the Spirit Lake Fish Hatchery staff anxiously awaits the ice off from the waters of what they call their brood lakes — Spirit Lake, East Okoboji and West Okoboji. Once they can get in with their boats and gill nets, they are ready to haul in the northern pike.

Fish spawn at varying times, based on a combination of water temperature and photoperiod (the amount of daylight hours). At Spirit Lake, it’s the northern pike that are ready to spawn first.

“We have to go out into the sloughs were they are staging to spawn and get them,” explained Muhm. “The lake itself may not be open, but if the sloughs are open, we can get in there with nets and get them out.”

The catch is then brought to the hatchery, where females are sorted into two groups — those that are “ripe,” or ready to spawn, and those that are green. While it isn’t known just how old a northern pike must be for reproduction, Muhm said they have caught pike as young as 2 years old that have produced eggs.

Using a dry method — dried-off fish, dry hands and a dry pan — staff members express the females’ eggs into a pan, where they are later mixed with milt collected from the males and water.

“There’s a pore on the egg called a micropyle that opens in the presence of water,” Muhm explained. “It’s only open for about 60 seconds — that’s how the sperm enters the egg. We want the sperm there and ready to go as soon as we open the micropyle.”

The milt and water are swirled with the eggs for two to three minutes, and then the eggs are rinsed before being soaked in lake water for about four hours. Soaking the eggs allows them to develop a hardened outer shell.

The eggs are then placed in jars and put on incubators, where heated water runs continuously to keep them oxygenated. About 10 to 12 days later, the eggs have hatched.

The process of egg harvesting is the same for walleye and muskellunge, although walleye eggs take 18 to 24 days to hatch because cold water is used for the incubation process.

“We don’t heat the water for the walleye because we just have way too many — 100 million eggs is a lot,” Muhm said.

Walleye eggs must also be coated with a clay mixture after they’ve been fertilized to keep the eggs from sticking together. The mix is washed off before the eggs are placed in incubators.

Walleye and muskellunge are harvested from the brood lakes after the water temperature has reached 45 degrees. Crews go out at night with gill nets and find them closer to the shoreline, where they naturally move to spawn.

“Crews will go out every night until we have enough fish to meet our quota of eggs,” said Muhm. “Last year, it only took four nights, which was a record. It can take quite a while, but we have a huge population of fish that are just coming to the breeding age in Spirit Lake, and we caught 1,400 in one night.”

Walleye must be at least 4 years old or older to reproduce, while muskellunge need to be 4 years old or older and at least 30 inches to 36 inches in length.

Fisheries people from across the state come and help the hatchery during entire process, which typically takes about six weeks.

In addition to harvesting eggs and milt, the hatchery also has a tagging system in place to help track fish. Every fish that enters the hatchery is recorded by sex, reproductive stage and the lake it was netted in. When the process is complete, each fish is returned to the lake from which it came.

Food for thought

When the walleye fry first hatch, Muhm said they look like a strand of hair with eyeballs — “they’re very, very tiny.”

The northern pike and muskellunge, on the other hand, look like pine needles when they’re babies and look like little sticks after they’ve grown a bit.

“It’s really kind of interesting how they change during their larval stage — they don’t look like the species they are until they get a little older,” she said.

Getting them to the point where they actually look like fish takes a lot of work — and a specialized feeding program.

Dry feed is fed to both the northern pike and muskellunge as soon as they absorb the yolk sac with which they were born. (The yolk sac serves as their food source until they form feeding mouth parts that aren’t present when they are born.)

The dry feed is fish-based, because predator fish normally eat zooplankton first in the wild, then graduate to aquatic insects and larvae. Eventually, as they grow big enough, they will eat other fish, including each other, Muhm said.

“That’s one of the problems we have with raising swim-up fry. There’s a point when they want to switch to a diet of fish,” she said. “We have to give them something that tastes pretty good to them — a fish-based, high-protein food.”

The dry food doesn’t work for walleye because they are so small, so the walleye fry are taken to nursery lakes where they can eat natural food.

“We can get them when they’re 2 inches long and then put them on dry food, which is what we do,” Muhm said. Stocking the state

Each summer, management biologists with the Iowa Department of Natural Resources collect data on fish populations from bodies of water located in their assigned 10-county districts. That data is used to determine what kinds of fish and approximately how many will need to be stocked in each of the lakes.

“In late fall and early winter, they draw up their list of what they want and submit it to the head of fish hatcheries,” said Muhm. “We get the requests of what they need, by species.”

The complete report is hundreds of pages in length and includes requests for more than just the walleye, muskellunge and northern pike hatched and reared at the Spirit Lake facility.

Muhm said it’s typical that the same lakes receive the same fish each year — mostly because of fishing pressure. Events like floods, droughts, winter kill and pollutants that lead to fish kills also dictate when and how many fish need to be restocked.

The type and location of a water body dictate what type of fish will get stocked there. For instance, southern Iowa lakes do not get stocked with northern pike or muskellunge because they cannot survive in the warmer water temperatures.

“Here in the (Iowa) Great Lakes, we have lots of different kinds of predator fish,” said Muhm. “We’ve found through research that the 2-inch walleye that we produce in our nursery lakes do extremely well in river systems, so we stock a lot of them in rivers.”

Many of the northern pike reared at the Spirit Lake Fish Hatchery also are stocked in the river systems.

As for muskellunge, the hatchery raises more than it can use because it has trade agreements with other states. Muskellunge are traded at 2-inch and 4-inch sizes to states that can supply Iowa with fish it does not rear.

“We provide Missouri with muskies in exchange for catfish,” Muhm said. “Hybrid striped bass and small mouth bass come from various places, so we typically trade muskies for those. It just depends what the need is at the time.”

Approximately 3,500 muskellunge are reared at the Spirit Lake Fish Hatchery, which is the only Iowa hatchery to rear the giant predator fish.

“Most lakes in Iowa are stocked every other year with muskie; there are only a few lakes in Iowa that get muskies,” Muhm said.

Need for growth

While Muhm said expansion would be welcome at the fish hatchery, it isn’t likely to happen in the near future. Iowa is in the midst of tightening its budget, and the fisheries department won’t be left unscathed.

“We may be curtailed the next year severely,” she said.

In Iowa, the fisheries, wildlife and law enforcement bureaus are all funded through the sale of hunting and fishing licenses. They get no additional dollars from the state’s general fund. While fishing license sales remain strong, the state has seen a decline in requests for the higher revenue-generating hunting permits.

For now, there is adequate money generated through license sales for the fish hatchery to operate with minimal cuts, but Gov. Terry Branstad has put a cap on how much money the state’s fishing bureau can spend.

“When the governor makes cuts, he wants to make everyone suffer the same,” Muhm said. “They can’t take money away from us, but they can keep us from spending it.”

That means the fish hatchery at Spirit Lake may not rear as many fish next year, if the cap remains in place.

“We have to cut money from the budget somehow,” said Muhm, who hasn’t seen a budget increase in the 11 years she’s worked at the Spirit Lake Fish Hatchery.

The hatchery has an annual budget of $500,000, the majority of which goes to personnel. There are six fulltime employees at the hatchery, and two more with seasonal jobs. Statewide, the fisheries bureau employs a staff of 98.

“It’s a tight budget year, and a tight budget coming up,” Muhm said. “Usually during the lean budget years, when we ask for license fee increases, we get turned down. There’s lean years coming.”

Plan a visit

The Spirit Lake Fish Hatchery will shift into high gear in early- to mid-April, or as soon as the ice is gone from the lakes and sloughs used to net fish.

“Usually when we start gill netting, we are staffed 24 hours per day, but we close to the public at 10 p.m.,” said Muhm.

The doors open at 8 a.m. seven days a week for the approximately six-week season.

Scheduled tours are offered for schools and other groups and can be arranged by contacting the fish hatchery’s office manager at (712) 336-1840. Individuals and families are welcome at any time. Informational displays are set up for self-guided tours, but questions may be asked of staff while they work.

Muhm encourages people to call ahead to ensure the hatchery has begun its harvesting, hatching and fishtagging processes. When that work wraps up in about mid-May, the facility reverts to normal hours, which are from 8 a.m. to 4 p.m. Monday through Friday.

On the Net:

www.iowadnr.gov/fish/pro grams/hatchery/spiritlak.html

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