For nearly half of March, biologists and technicians from the Ohio Department of Natural Resources Division of Wildlife spent their time netting walleye in Mosquito Lake. Their goal was to make more walleye — or, in some cases, saugeye — to release there or in other lakes and reservoirs. But they also make a lot of fans.
Anglers aren’t allowed on the netting boats but are welcome to pull up nearby and observe. And when the walleye make it to the dock, where eggs and sperm are harvested and combined, “they always draw a big crowd,” said Dan Wright, a fisheries management technician.
“We do a lot with education, including some school groups.”
Unless there is ice preventing it, netting usually starts around March 15. That is when walleye come to shallow water, looking for proper breeding habitat. For walleye, that’s a hard, rocky bottom.
Division staff put their nets out in shallow water where they hope to find more females, as well as more that are ready to release their eggs.
A single female can carry as many as 150,000 eggs, Wright said. When breeding occurs naturally, there’s a bevy of bachelors swimming around a female that is ready to spawn. What they do to make her release her eggs almost sounds like domestic abuse.
“Biologists talk about walleye rolling,” Wright said. “The female swims higher in the water column, then the males swim under her and beat on her belly with their noses. They basically push her to the surface, and it looks like she’s rolling in the water.”
Walleye are scatter spawners, he said. As the female releases her eggs, the males release their sperm. The eggs are fertilized almost instantly as they drift to the bottom. And then are totally ignored.
That’s very different from the breeding habits of, say, bluegill or bass. In those species, females lay eggs in specific places, then the males guard them until they hatch.
Most walleye prefer to breed in places with a current, which keeps the bottom clean. There is no current in Mosquito Lake, but there is usually enough wind on the eastern bank to make waves, which have much the same effect.
In Mosquito, “we put out 16 nets that are between 60 and 150 feet long,” Wright said. “We set them from the dam on the southern end all the way to the Route 88 causeway.”
Walleye hoping to breed come to explore the shallow water near the shore, then are pretty much funneled into the nets. Wright and the rest of the walleye-netting crew get to Mosquito about 7 a.m. each morning to “run the nets,” he said.
They take out any walleye that have been caught and release everything else back into the lake. In fish biology terms, everything else is called “bicatch.”
The bicatch this year included crappie, channel catfish, flathead catfish, largemouth bass, northern pike, yellow perch and various bait fish. But other years there was the occasional mudpuppy, “which made things interesting,” Wright said.
If they’re “making walleye” that day, the staff will need to harvest both eggs and sperm. In that case, both the walleye males and females that are caught are kept and put in tanks in the boat.
“If we’re making saugeye that day, we just keep the females,” he said.
Saugeye are hybrids, the result of walleye eggs and sauger sperm. Walleye tend to spend more time offshore, while sauger are river fish.
Saugeye tend to do better in Ohio’s inland lakes, Wright said. And because they’re hybrids, they grow faster and are more aggressive, making them popular with anglers. Saugeye are usually “made” during just a few days in the middle of netting season.
That’s because the sauger that donated sperm were caught by electrofishing on the Ohio River about a week before netting began. The sperm were transported from a hatchery, and could only be kept alive so long.
The hatchery folks needed an average headcount on the female walleye to know how much sperm to bring.
Back on the boat, biologists who find walleye in their nets give the fishes’ bellies a little squeeze to see whether eggs or sperm come out. That’s how they know whether the fish are male or female; in other words, which to keep and which to throw back.
If the fish is a female, biologists squeeze again to see if a larger number of eggs come out. If that doesn’t happen, she’s not “flowing” or ready to release the eggs, Wright said. She’s then put back in the lake, perhaps to be caught again at a more opportune time.
Male and female walleye are already separated into different tanks when the boats get to the dock. Then the hatchery people take over.
Fertilized eggs from Mosquito Lake go to three different state fish hatcheries: Senecaville, near Salt Fork; St. Mary’s on the eastern bank of Grand Lake St. Mary’s, and Hebron, north of Buckeye Lake. All three are run by the Ohio Division of Wildlife. The hatchery staff on the dock start with female walleye, squeezing their bellies to make the eggs drop into pans — just roasting and baking pans that can be found in any store. Each pan is filled with the eggs of several females. If it’s a walleye day, the bellies of male walleye are squeezed over the pans to make the sperm or milt come out.
That part is usually pretty easy because “male walleye are like teenage boys,” Wright said.
When the sperm lands on the eggs, hatchery staff stir the mixture with a goose feather. Why goose? They’re soft enough so they don’t bruise the eggs, but strong enough to get the eggs and sperm to mix well, he said. If it’s a saugeye day, sauger sperm from the hatchery is put on the eggs and stirred. Again, fertilization is almost instantaneous, so five minutes of stirring is usually sufficient.
Afterward, the fertilized eggs are put in water containing tannic acid, which removes the sticky coating on the eggs. In nature, the eggs would be stuck to a rock with water flowing all around. In the hatchery, there could be as many as 125,000 eggs in each quart jar, into which water is pumped.
“They don’t want the eggs clumping or sticking together in the jars,” Wright said. “The water needs to circulate so the eggs can get nutrients and oxygen.”
The hatchery staff on the dock then add water to the fertilized eggs to make them harden and form a protective layer. The water that is added comes from the specific hatchery where the eggs will be sent.
After that, the eggs are placed in an iodine solution to remove any contaminants.
Invasive zebra mussels can be found in Mosquito Lake, along with a bacteria that can cause sepsis. “We don’t want those contaminants to get into other lakes and waterways,” Wright said.
The goal in netting walleye is to get 800 quarts of eggs, which are divided between the three hatcheries. The hatcheries also get eggs that originated from walleye in the Maumee River. The eggs usually take two or three weeks to hatch, depending on the temperature of the water that is flowing through the jars at the hatchery.
About 80 percent of the eggs in those jars will hatch successfully, a hatch rate that far exceeds that in nature, Wright said. When the eggs have hatched, they are either bagged up and sent to lakes and reservoirs as fry, or released into hatchery ponds to grow into fingerlings.
Lakes in Ohio are stocked at the rate of 1,000 fry or 200 fingerlings per acre. That means Mosquito Lake gets 7.2 million fry and 1.4 million fingerlings, Wright said.
Without the efforts of the division of wildlife staff at both Mosquito Lake and the Maumee River, “walleye and saugeye fishing would not exist at inland lakes across Ohio,” he said. “Because of these efforts, walleye and saugeye will continue to be stocked for anglers to enjoy.”
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