Here’s to Hoover-Mouth

There are species of fish in your lake that you may rarely if ever see, yet are important to the health of the fishery. The white sucker is a classic example.

You may know this fish best as bait. Raised in ponds, it is sold in increasing sizes for walleyes, northern pike and muskies. If like me you grew up on a Lake Michigan tributary, you may have fished for suckers using a dip net hung by a rope from a bridge, in springtime when the fish migrate upriver from the lake to spawn.

If your lake contains suckers, why don’t you see them? Well, because they tend not to take what anglers offer. I’ve fished for more than 50 years and have caught just one white sucker from a lake on hook and line.

Suckers are mainly bottom-feeders and have mouths well adapted to that purpose. The leathery lips aim downward instead of straight ahead, so the fish can cruise along, dining in comfort, casually vacuuming up food like insect larvae, worms, small mollusks and crustaceans, plant matter and fish eggs from the sediment. In turn, suckers are a vital food for favored game fish; they may also be eaten by herons, loons, bald eagles and osprey.

White suckers live in almost any lake and stream here in Northern Wisconsin. In fact, they’re abundant throughout the Northeast and Midwest U.S. and in parts of the Northwest. They do fine in clear, clean waters but also tolerate relatively low dissolved oxygen and so can thrive in turbid urban waterways.

Suckers have fine scales. Sides are dark greenish with a metallic luster; the belly white, and hence the common name. Adults can grow up to 20 inches long and weigh two pounds or more; musky anglers are known to use those at the top of the size range for bait in the fall.

Spawning generally starts when the fish are about four years old (later in colder climates where they grow more slowly). Spawning season runs from April to early May. The fish move into streams or, in lakes, select bottoms of gravel or coarse sand. The actual spawning happens at night. Most often, two males mate with one female. With one male to each side, the female lays 20,000 to 50,000 eggs, which the males fertilize.

The fish do not make spawning nests and do not care for the eggs, which simply sink to the bottom. The eggs hatch in five to ten days, and a week or two later the fry leave the spawning area and disperse.

Thus are born swarms of fish on which your lake’s most prized species may depend for growth. So even if you never see suckers on your lake except in your bait bucket, be sure to assign them a little respect. Here’s to Hoover-Mouth!

How does your lake get its water?

You’ve read here about classifying lakes by trophic state – how poor or rich in nutrients they are. But that’s not the only way to categorize them. Another, just as interesting, is by how water gets in and out.

The number of lake types based on source of water depends partly on who is doing the defining. The Wisconsin Department of Natural Resources lists four types, but there is a fifth that many geologists mention. Here are five basic lake types found in Northern Wisconsin and Upper Michigan:

Drainage lakes. On these lakes, a stream brings water in, and a stream takes water out. That is, the lake has an inlet and an outlet. Some lakes may have more than one of each. The water level in these lakes tends to stay fairly constant. Think of a bowl into which you run a slow flow of water from the tap: An equal amount of water flows in and flows out. I live on a drainage lake and its level is largely self-regulating. In 30 years, through wet times and dry, there has been at most a foot of difference between the highest and lowest levels.

Spring lakes. These lakes have no inlet on the surface, but they do have an outlet. They get their water mainly from groundwater flowing in. Many streams originate in spring lakes, which are quite common in northern Wisconsin.

Seepage lakes. These lakes have no stream flowing in or out. Their water comes mainly from rainfall and runoff, sometimes supplemented by groundwater. Their water levels are therefore cyclical, rising and falling with wet and dry years and their effects on the water table.

Drained lakes. These lakes are like spring lakes in that they have an outlet but no surface inlet. They differ in that they are not fed by groundwater – they get their water almost solely from rainfall, snow and runoff. For that reason, their levels can fluctuate greatly. During long dry spells, the streams flowing out of these lakes may dry up. Drained lakes are uncommon here in northern Wisconsin.

Perched lakes. These lakes are truly landlocked. They have no inlet, no outlet, and no contribution from groundwater. In fact they sit on relatively high ground, above the water table, with dense bottom sediments that hold the water in. Water levels in perched lakes can drop dramatically during long dry spells.

If you want, you can add a sixth type of lake: Reservoirs. These of course are like drainage lakes in that they have a stream inlet and outlet. The difference is that they were created by humans – they wouldn’t exist if not for dams. Here in the northern Wisconsin we have the Willow, Rainbow, Turtle-Flambeau, Chippewa and other smaller flowages.  

Which type is your favorite lake? If you don’t already know, consider doing some investigating to find out.