Freshwater jewels

You’ve probably seen neon tetras, bleeding hearts, clownfish and yellow tangs in aquariums. In all likelihood a fish just as beautiful, or more so, swims in your lake.

For my money, no fish is prettier than the sunfish – officially the pumpkinseed. I sometimes question why they are named for something as nondescript as those off-white ovals pulled from Halloween jack-o-lanterns. But of course the name “sunfish” belongs to a family of fishes that include the bluegill. Still, what the experts call pumpkinseeds are always sunfish to me.

Bluegills are pretty fish in their own right, but they look pale next to sunfish: Those eyes with bright-red iris around the dark pupil. The wavy lines that radiate from the mouth across the gills, in a color like aquamarine charged by blacklight. The deep black gill spot with the accent of brilliant red. The subtle pattern of blue-and-emerald vertical bars across the golden body. And then that bright yellow-gold belly.

Years ago (and I’ll admit I did this illegally, without a permit) I kept a couple of sunfish in an aquarium – they looked great amid the green artificial weeds, lit by the fluorescent lamp, and our toddler daughter loved watching them.

Fortunately for us all, sunfish are extremely common. They’re generally not as abundant as their bluegill cousins, but you can find them in almost any lake. They live in the shallower water and in the weed beds, eating mostly insects and their larval forms. They prefer water temperatures in the low to mid-70s. They live up to 10 years and can grow to 8 or 9 inches, though you won’t often see specimens that size around here.

Sunfish are easy to catch. They’ll take almost any live bait – worms, grubs, crickets, small leeches – but also artificials like dry flies, poppers and small spinners. When fishing with kids, nothing will bring more cries of delight than one of these jewels, popped from the lake, multiple colors glistening in an evening sun.

Why can you see better into water with polarized glasses?

Many of us know we can discern more features in shallow lake water when wearing polarized sunglasses. It’s easier to see fish we want to catch, observe bottom features, or discover treasures like lost fishing lures with those glasses on. But how exactly do polarized lenses work?

They do it by filtering out reflected light. Light consists of waves that are oriented in all directions. Light waves that reflect off water (or any surface) are oriented horizontally – think of a flat sheet of paper, parallel to the water, coming toward you edgewise. That light is said to be polarized.

Now, the lenses of polarized sunglasses are specially treated so as to form filter that acts like a vertical picket fence (except that the spaces between the fence “slats” are extremely small). Imagine you’re holding a long rope that’s tied off against a tree. Between you and the tree is a picket fence, and the rope passes between two of the fence slats.

If you were to move your end of the rope rapidly up and down, you would create a wave in the rope, and that wave would pass right between the vertical fence slats and reach the tree. Now imagine moving the rope rapidly side-to-side. The narrow space between the slats would block the formation of a horizontal wave, which would never reach the tree.

That’s what polarized sunglass lenses do to reflected light. Light that would otherwise impede your ability to see into the water is filtered out before it hits your eyes. Light waves with a vertical orientation are allowed to pass through, revealing all those secrets from below the surface.

So, when on your lake exploring, wear your polarized glasses. You’ll get to know a little more about your lake. Not as much as if you looked below the surface through a snorkeling mask – but that’s a subject for another time.

Can walleyes make a lake clearer?

We all like our lakes to be clear, and most of us prize walleyes as a sport fish and table fare. But is there a connection between the two? Between walleyes and water clarity?

I learned at this year’s Wisconsin Lakes Partnership Convention that there can be. Scott Van Egeren, a water resources management specialist with the state Department of Natural Resources, gave a talk on the food chain in typical lakes such as we have in Wisconsin.

To oversimplify matters a bit for brevity, the food chain starts with one-celled algae (plant plankton, or phytoplankton), which are eaten by animal plankton (zooplankton), which include small crustaceans like Daphnia (water fleas). Fish such as cisco (planktivores) eat the algae eaters, and predatory fish, including walleyes, eat the cisco.

Now, what has that to do with water clarity? Well, in general, the lower the level of algae in a lake, the clearer the water. And in general, the more algae-eating water fleas are present, the less algae there will be. But what happens if cisco (and other smaller fish) are abundant and are gobbling up the water fleas? That means fewer algae-eaters, more algae, and cloudier water.

And here is where walleyes come in. Walleyes graze on cisco. If the walleyes are abundant, they can thin out the cisco and other smaller fish considerably. That means the water fleas and other algae-eaters have a chance to thrive, and the algae population goes down. And the water is clearer.

Now, of course, water clarity has to do with much more than just the walleye population. An important factor is the level of nutrients – which cause algae to thrive and can lead to nuisance blooms. Other factors include lake depth (deeper water has more capacity to absorb nutrients), surrounding land uses (which can contribute sediment in runoff), and wind and wave action, (which especially in shallow lakes can stir up sediments from the bottom).

But it’s interesting to think that a healthy population of walleyes can have a benefit beyond providing mornings and evenings of excellent fishing.

How do you like these odds?

Look in the shallow water around your pier these days and you may see schools of hundreds of tiny fish – probably newly hatched bass, perch, bluegills or other species. If you were to imagine many more such schools around the lake’s perimeter, you might assume your lake would soon be chock full of fish for catching.

The reality is far different. The odds of survival for these fry are exceedingly long. One scientific study used DNA tracking to estimate the success of spawning smallmouth bass on a lake in Ontario. To make a long story short, the study found that only 27.7 percent of male bass that acquired eggs (it’s the male who guards the young after the eggs hatch) had at least one offspring survive to the fall young-of-the-year stage. Just 5.4 percent of all the spawning males produced 54.7 percent of the total number of the fall young-of-the-year, which range in size from 1 1/4 to 3 inches.

To look at it another way, consider that female smallmouth bass deposit anywhere from 2,000 to 10,000 eggs on a spring spawning bed. Even under the best conditions, most eggs don’t survive. They’re vulnerable to changes water temperature and oxygen levels, flooding or sedimentation, disease and predation (as from panfish and crayfish).

When the eggs hatch, the larval fish live off a yolk sac attached to their bodies. Once the yolk is fully absorbed, the fry, about an inch long, rise from the bed and start eating on their own. For a time the male bass protects the school, but eventually he leaves and the fry scatter. They survive on tiny crustaceans until they are big enough to eat aquatic insects, then larger crustaceans and fry of other fish species that spawned later. As the fish grow, they face the same threats as the eggs – in addition to which all manner of predators feast on them.

When they’re small, they get attacked by bluegills, perch, pumpkinseeds and sunfish. As they grow, they become prey for walleyes, northern pike and muskies. Other enemies, again depending on the fishes’ size, include kingfishers, loons and herons, mink, frogs, and some snakes. The end result is that only a tiny fraction of the eggs laid in a spawning bed, and only a tiny fraction of the fry you may see near your pier, ever become adult bass. Yes, nature can be a cruel mother. I am certainly glad the odds of survival for our grandsons, Tucker and Perrin, are considerably better than for a newly hatched smallmouth bass.