The ice abides: The otter slides

Last winter for the first time, on one of my walks around the rim of Birch Lake, I saw otter tracks in the snow. I wasn’t certain that’s what I had seen until I did a little research – which also told me I wasn’t rightly interpreting what I had seen.

Along the frozen shore of your lake is a great place to look for otter tracks, especially before the snow gets too deep. Otters (technically river otters, scientific name Lontra canadensis) come out of their winter burrows, usually near water, to forage for food.

The tracks I saw had paw-print trails interrupted by long, slender depressions in the snow. I assumed those depressions were made by the otter’s belly dragging. That wasn’t quite accurate. Actually, according to an article from Wisconsin Natural Resources magazine, otters “conserve energy moving across the snow by taking a few bounds and then sliding on their tummies. From above, these tracks look a bit like Morse code, in a dot, dot, dash pattern.” Otters can travel quite fast, about 15 to 18 miles per hour, faster than most people can run.

So knowing what I do now, I am even a little more inclined to be anthropomorphic about otters and say: Here’s an animal that knows how to enjoy life.

I followed the trail of last winter’s otter until I came to a hole in the ice up against a mucky shoreline interlaced with tree roots, near our lake’s outlet to a creek. I had followed him (or her) home. Go down to your lake soon and see if you can’t find an otter’s trail to follow across the snow. 

The ice abides: If Thoreau had a Secchi disc

Your lake is probably clearest at the time you’re least likely to be looking down into it – which is now, in winter, the water encased in ice and covered with snow.

Lakes clear up in winter for a variety of reasons. Cold water slows down the growth of algae (phytoplankton). In addition, the snow cover shuts out sunlight so that the algae cannot photosynthesize (make food) and so die back. Also, in essentially a closed vessel, the water is very still – no wave action from wind or boaters means bottom sediments are not stirred up and particles suspended in the water can settle out. There’s no rainfall runoff to wash soil and debris into the lake. Water still enters from springs, but that’s groundwater, essentially clear.

If you’re lucky enough to experience an early winter when the lake freezes solid enough to walk on, and a week or so goes by with no snow, you can enjoy a real spectacle. Even in fairly deep water, you can see all the way to the bottom and make out every detail.

Scenes like this remind me of a favorite passage from Henry David Thoreau’s Walden, telling about the clarity of the author’s beloved pond:

“Once, in the winter, many years ago, when I had been cutting holes through the ice in order to catch pickerel, as I stepped ashore I tossed my axe back on to the ice, but, as if some evil genius had directed it, it slid four or five rods directly into one of the holes, where the water was twenty-five feet deep.

“Out of curiosity, I lay down on the ice and looked through the hole, until I saw the axe a little on one side, standing on its head, with its helve erect and gently swaying to and fro with the pulse of the pond; and there it might have stood erect and swaying till in the course of time the handle rotted off, if I had not disturbed it. Making another hole directly over it with an ice chisel which I had, and cutting down the longest birch which I could find in the neighborhood with my knife, I made a slip-noose, which I attached to its end, and, letting it down carefully, passed it over the knob of the handle, and drew it by a line along the birch, and so pulled the axe out again.”

I wonder what a Secchi disc clarity measurement would have yielded in water that clear. Of course, Walden pond was naturally clear – Thoreau reported seeing the bottom 25 to 30 feet down while canoeing even in mid-summer. Your lake most likely is not that clear; my lake (Birch, near Harshaw, Wis.) certainly isn’t. Still, I long to experience an early December of clear ice. It almost happened this year. A couple of cold, still nights created a smooth skin, but then came snow. Now about a foot of snow lies on the ice; there will be no looking down into clear, cold water this year.

The ice abides: Turtles in winter

On my winter walks on the Birch Lake ice I come upon fallen logs where, in summer, painted turtles line up to sun themselves.

You may have asked, “Where do the turtles go in winter?” And that’s an easy answer, right? To the lake bottom, to hibernate. But then, we know turtles aren’t like fish. They spend a lot of time underwater, it’s true, but they don’t have gills. They need to surface to breathe; we’ve seen their snouts poke up in calm water, then disappear.

So, if in summer they need to surface every so often for a breath, how do they survive under the ice for, say, four to five months with no access to the air? It turns out they actually can breathe down there – though not with their lungs, by way of the snout. And they need very little oxygen to make it through the winter, because their metabolism slows to almost nothing. 

At the lake bottom, the winter water temperature hovers around 4 degrees C (39 degrees F). Since turtles are cold-blooded, that becomes their body temperature. They become extremely sluggish; if they crawl or swim at all, it’s very slowly. Their hearts slow down to as low as one beat every ten minutes. They eat very little, if at all.

Yet because their body functions don’t shut down completely, they need oxygen. They get it from the oxygen dissolved in the water. It enters their bodies through the linings in the mouth and throat, and through two small sacs near the anus with very thin skin, laced with numerous tiny blood vessels. They could never survive breathing this way in summer, when their metabolism is high, but in winter, it’s enough. ← Larry the Bullfrog speaks about living in Wisconsin

Ice Fishing Contest on the St Croix Flowage Saturday, January 19 →

So unless we go through a winter of truly epic proportions, there will be enough oxygen in the water for turtles to survive. And next summer we’ll see them again, sunning themselves on those same old fallen logs.

The ice abides: When winter kills

When winter starts this way – snowy and very cold from early December – we know we’re in for a long slog until spring. We may worry about the birds, about deer starving in their yards, and about the fish in our lakes, especially if those lakes are shallow. We’ve all heard of winterkill. Can a lake really freeze clear to the bottom?

Well, not likely. But that doesn’t mean a long, cold winter can’t kill fish. It can, and it does. Only it’s not the ice that kills them – not directly anyway. They die from lack of oxygen, which is to say, from suffocation. The ice seals the lake, cutting off the supply of fresh air. The water’s oxygen level then has only one way to go, and that’s down. The fish themselves, and the decay of organic matter, use up oxygen. If the ice cover remains for too long, there’s so little oxygen left that the fish can’t breathe.

Fish need a certain level of dissolved oxygen in the water – at least 2 parts per million. An oxygen concentration below 1 part per million is lethal to many if it persists. Fish that are the most vulnerable are those in shallow lakes with lots of vegetation and mucky bottoms rich in organic matter.

“Winterkill begins with distressed fish gasping for air at holes in the ice and ends with large numbers of dead fish, which bloat as the water warms in early spring,” says an article on the Michigan Department of Natural Resources website. Of course, some fish tolerate low oxygen better than others. Bass, walleyes and bluegills are fairly tolerant; perch and northern pike are more so. Bullheads can withstand severe oxygen depletion.

“February is usually a critical period and is the best time to check the oxygen content of lakes prone to winterkill,” says the Michigan DNR article. “A good mid-winter thaw about then often recharges the lake’s oxygen supply by means of photosynthesis and melt water. Conversely, a prolonged winter, with continuous snow cover and late ice-out increases the chance of winterkill.”

People on many small lakes protect them against winterkill by pumping in air with motor-driven aerators. It’s effective, though not a permanent solution. The real answer is to reduce the amount of nutrients entering the lake – nutrients that feed an abundance of plants that ultimately die, decompose, and deplete the winter oxygen supply.

Property owners can help by avoiding lawn fertilizers and making sure their septic systems are functioning properly, instead of seeping nutrient-rich water into the lake. Of course, some lakes are just naturally rich in nutrients, and in such cases there isn’t much lake residents can do, short of an extremely costly process of dredging out sediment. Winterkill in such cases is just part of the natural cycle. 

What happens to lakes that go through winterkill? Well, seldom do all the fish die. Enough usually make it through to reproduce. If the lake has an inlet stream, fish may come in that way and repopulate it faster. Nature takes its course; things heal. Some even maintain that a minor or moderate fish kill can be good for a lake: The fish populations are thinned out so there is more food for the survivors, which then prosper and grow.

Still, a winter die-off is not something to look forward to. If you live on a shallow lake, or if you have such a lake as a favorite fishing spot, a long and harsh winter can be a legitimate cause for worry.

The ice abides: In cold blood

What’s it like to live under the ice? We’ll never know the sensations, because after all, we’re not fish – and we can never relate to their experience because our metabolism is radically different from theirs.

We are warm-blooded; fish (along with frogs, crayfish, turtles and other water creatures) are cold-blooded. Our bodies regulate our temperature; much of the energy we consume as food goes to feed the inner furnace that keeps us at 98.6 (or so) degrees F. Cold-blooded creatures’ temperatures rise and fall with the temperature of their environment, which means right now the fish in your lake are at somewhere around 40 degrees F, just like the water.

What does that mean in a practical sense? It means the fish are quite sluggish. Their muscle movements rely on complex chemical reactions that proceed rapidly when warm and slowly when cold.

Imagine what it would be like to live in cold water as the warm-blooded mammals we are. Staying warm would be impossible. Even at 70 degrees, water pulls heat out of our bodies dramatically faster than does air at a similar temperature. At 40 degrees water temperature, our bodies simply could not keep up; we would be uncomfortable to say the least and would die soon from hypothermia. Think about the mammals that live in water (like whales) or spend a lot of time in it (seals, sea otters, walruses). Their adaptations tend to include heavy fur, a thick layer of insulating blubber, or both.

Cold-blooded creatures are perfectly fine in cold water. They don’t have to heat themselves, which means they don’t use a lot of energy. They don’t have to eat a great deal in winter because the cold tamps down their metabolism. Ice anglers can see evidence of this in the fish they catch and clean – the stomachs are often full of food. Prey that might digest in a day in summer may take a week in winter.

You may have wondered, if you ice fish, why you catch certain species in winter more so than others. It’s because fish react differently to the cold. Walleye and northern pike eat plenty as ice forms, weeds die back, and prey fish become more exposed. Bass and muskies, on the other hand, don’t move around much and eat just enough to sustain basic functions.

Where do fish go in winter? Some stay relatively near the surface where the water contains more oxygen. Some hunker down in the depths. Bullheads bury themselves in the bottom, not actually hibernating but moving very little.Many fish hang around the same kinds of places they haunted in warmer times – weed beds, brush piles, manmade cribs and other cover. Bluegills, for example, crowd around cover for protection. The flips side is that their presence in turn attracts predators, like northern pike.

Right now, the air temperature over my lake (Birch, near Harshaw, Wis.) hovers in the single digits, and a wind whips over the snow. Talk about wind chill all you want, but being in the water below the ice would feel much colder. This warm-blooded creature is glad to have a heated cabin and a bowl of soup to come to after a walk.

The ice abides: What if you break through and fall in?

It’s every winter adventurer’s nightmare: Breaking through the ice on a lake or river and falling into deep, frigid water. It’s obviously an adventure to be avoided, but also to prepare for, just in case the worst should happen.

First, remember that ounce of prevention. If you’re not sure the ice is safe, stay off or, at the very least, stay where you know the water beneath you is shallow, so that if you break through, you can essentially walk out.

If you’re planning to venture out where it’s deep, ideally go with a companion. Go with a survival plan already mapped out in your head. And go with a little equipment, which includes proper clothing. If you are mentally and physically prepared, you will be less inclined to panic and more able to act appropriately.

Contrary to what you may think, winter clothing is not a handicap if you fall through the ice. Heavy clothes will not drag you down. They will trap air inside, helping you float and keep warm. Snowmobile suits are especially good in this regard.

It also helps to take along simple survival tools, in the form of spikes or a pair of screwdrivers. If you fall through, you can use them to gain enough traction to pull yourself back up onto the ice. Last winter my son made me a pair of ice picks, each with a half-inch or so of a nail protruding from a wooden handle. The picks are connected by a string that I can feed through my coat sleeves, so in case of an accident they would be at the ready; I would not have to fish in my pockets for them and would be at no risk of losing them.

As for taking action, here are a few ice accident survival tips from the Minnesota Department of Natural Resources:

• If you fall in, turn back toward the direction from which you came. Chances are the ice is stronger there.
• Place your hands and arms on the ice surface and hold yourself up. If your clothes have trapped a lot of water, you may have to lift yourself partly out of the water, such as on your elbows, to let the water drain – lightening the load – before you start forward.
• This is where the ice picks (or screwdrivers) come in. Reach out, jab them into the ice, and try to pull yourself up. As you do that, kick your feet to provide forward propulsion (think of those kick boards you used in swim lessons).  
• Once you are on solid ice, lie flat and roll away from the hole. This keeps your weight distributed and may help prevent your breaking through again.
• As soon as you can, get to a warm, dry, sheltered place.

The lake ice is wonderful, but don’t push your luck. Be careful – and be prepared – when you do go out.

The ice abides: Be careful out there

Late in the movie Titanic, a couple of the lead characters slogg their way through waist-deep water in the ship’s passageways as they try to escape. The flaw in these scenes is that the people show no signs of physical comfort – only emotional panic – when the reality is they would have been in utter agony.

I grew up on Lake Michigan and remember what it was like at the beach on days when the water temperature was in the mid- to high 50s. Step in and within seconds your feet would ache; you just had to get out and take a break. You could get accustomed to the water after a while and the pain would subside; you might even decide take a dip. But that first encounter with the water? Brrrrr! 

Now imagine how water at around 32 degrees would feel. And in the ice-strewn North Atlantic where the Titanic went down, the water might have been even colder than that. Dissolved salt lowers water’s freezing point; seawater freezes at 28 to 29 degrees F.

But I digress. The point I am getting to is that you want to be careful on your lake now that, most likely, ice has taken hold, as on Birch Lake, near Harshaw, Wis., where I live. Because if you were to break through, drowning might not be your most pressing concern. Hypothermia likely would be.

Odds are that if you broke through you would find yourself holding onto the “shelf” of unbroken ice around the hole you made. And the very cold water would go to work on you immediately. If the water you fell into were between 32 and 40 degrees – a likely scenario on our winter lakes – you would have 15 to 30 minutes before becoming exhausted or losing consciousness. That’s according to the United States Search and Rescue Task Force (USSRTF). Here is how the USSRTF describes the effect of falling into frigid water:

“The first hazards to contend with are panic and shock. The initial shock can place severe strain on the body, producing instant cardiac arrest...Survivors of cold-water accidents have reported the breath driven from them on first impact with the water. Should your face be in the water during that first involuntary gasp for breath, it may well be water rather than air. Total disorientation may occur after cold-water immersion. Persons have reported “thrashing helplessly in the water” for 30 seconds or more until they were able to get their bearings.

“Immersion in cold water can quickly numb the extremities to the point of uselessness...  Within minutes, severe pain clouds rational thought...finally, hypothermia (exposure) sets in, and without rescue and proper first aid treatment, unconsciousness and death. Normal body temperature of course, is 98.6 [degrees F]. Shivering and the sensation of cold can begin when the body temperature lowers to approximately 96.5. Amnesia can begin to set in at approximately 94, unconsciousness at 86 and death at approximately 79 degrees.”

So, don’t kid yourself that you could easily survive a trip down through your lake’s ice. Be extremely careful out there. In the next post I’ll pass along some experts’ tips on what to do if you were to break through – or how to help a companion who has that misfortune.

The ice cometh: A few facts and figures

To get to know the ice on your lake, it helps to know its physical properties. Here are a few worth noting.

•         Density: 0.916 grams per cubic centimeter at 32 degrees F. For comparison, the density of water is one gram per cubic centimeter.
•        Stiffness modulus: This is a measure of how stiff a material is. The stiffness modulus of ice is about 1.5 million pounds per square inch – or about three times as stiff as a hard plastic.
•         Heat of melting (or heat of fusion): 80 calories per gram. This is the amount of heat required to melt a gram of ice that starts at a temperature of 32 degrees F.
•         Heat capacity: This is the energy required to raise the temperature of a gram of ice one degree Celsius: 0.50 calories per gram. Interestingly, this is only half the heat capacity of liquid water.
•         Fracture toughness: This measures how easily a crack spread through a substance. Ice is about one-tenth as tough as glass in this respect.
•         Thermal conductivity: Ice conducts heat almost four times as well as water.
•         Refractive index: Light travels more slowly through a solid material than through air or a vacuum. The speed of light in ice is about 75 percent of its speed in a vacuum.    

The ice cometh: Why won’t moving water freeze?

Yesterday strong winds blew across Birch Lake; as I stood on our frontage it smacked me straight in the face, the temperature in the single digits, the wind chill factor surely below zero. The near-shore water lay frozen; a few yards out, slabs of ice, like pieces of a crude jigsaw puzzle, rose and fell on waves. Other than that our lobe of the lake was open, choppy in the wind. Looking left toward the narrows leading to the other, more wind-protected lobe, I saw that it was frozen, covered in snow.

All it would take now, I thought, would be a cold, still evening, and the lake would freeze clear across. This morning confirmed my belief. Looking out from our hill as the morning brightened, I saw an unbroken sheet of white, a skin of ice dusted by the night’s light snow.

And I wondered: Why did it take a still night to make the lake freeze? Why wouldn’t it freeze despite the wind and waves? After all, 32 degrees is 32 degrees, and 8 degrees is 8 degrees. What difference should wind make in whether water gives up its requisite 80 degrees of heat energy per gram and freezes?

I searched all over the Internet without finding a satisfactory answer. One place said the motion of the water meant the molecular motion could not slow down enough to lower the temperature. I rejected this on the grounds it seems to confuse the macroscopic motion of the water with the sub-microscopic motion of molecules that correlates with temperature -- are we to believe that the mere fact of physical motion imparts heat? Another source said the mechanical motion of the water continuously fractures any ice crystals that form. I don’t have a technical argument against this; it just doesn’t seem plausible.

So I came up with a theory of my own, which is that the wave action creates a stirring effect, bringing up warmer, denser water from below and sustaining the surface temperature above freezing. Remember that, as earlier posts have said, water is the most dense at about 4 degrees C (39 degrees F). So the temperature gradient in a lake in winter runs from near zero degrees C at the surface (32 degrees F), gradually down to 4 degrees C. If the surface is heavily disturbed, as it was yesterday, then the agitation would be constantly bringing up warmer (or less cold) water from below, so that the surface water could not reach the freezing temperature. Then, once the wind calmed down and the water lay smooth, the surface water would readily give up its heat to the far-below-freezing air above and turn to ice.

Well, then, a critic might say, what keeps a river or creek flowing all winter, no matter how cold it gets, even if the river is rather slow-flowing and there is no wave action to speak of? Here we need to remember that a river or creek is not a closed system. In winter its source is likely, to a great extent, groundwater, which in northern latitudes is going to bubble out of the earth at temperatures in the low 40s F. Water at that temperature will enter continuously at numerous points along the stream’s route, so there is no real possibility of freezing. Of course many rivers do freeze on the surface, although the water beneath keeps flowing.

Now, as for Birch Lake, which has only a very small creek running in and out, and so is to a large extent a closed system in winter (absent snow melt and runoff) – what if the temperature remained at, say, 10 degrees indefinitely, and strong winds continued for weeks on end? Would the lake’s surface ultimately freeze?

That’s a good question. Does anyone have an answer? And would anyone care to confirm or shoot down my theories as to why rivers, streams and wind-blown lakes won’t freeze despite very cold air above them? I am all ears.

The ice cometh: Hear it boom

Ice is slowly taking hold here on Birch Lake, near Harshaw, Wis. Actually the lake had a skin of ice over more than half its surface late last week, but that was before winds kicked up. Last night the temperature was in single digits, where it remains this mourning, yet our entire lobe of the lake – more than half the total surface – is wide open. A 20 mph winds is keeping it so. If things calm down and the weather stays cold, we are in for a very fast freeze.

As I wrote earlier, this ice is a fascinating substance. One of its properties is its expansion. Most compounds contract when they cool and expand when they warm up. At the level of chemical structure, that means the molecules pack closer together when the substance is cold and spread out when it is warm.

Water and ice break that pattern. In liquid water (H₂O), each molecule – two hydrogen atoms (H) and one oxygen atom (O) – is bonded to three or four others. In ice, each molecule is bound to four others. That means more open space between the molecules, and so an expanded – thus less dense – substance.

As kids my brother and I found our about the expansion of ice when we left a few quart bottles of pop on the enclosed but unheated porch one very cold night. In the morning the necks of the bottles were blown clean off (or parents were not amused). Actually expanding ice is a nearly irresistible force. Water that creeps into a crevice in a rock can break that rock apart when it freezes. The expansion if ice is responsible for much of the natural weathering that takes place in northern landscapes.

How much does ice expand? About 9 percent by volume. Stated another way, ice is about nine-tenths as dense as water. This is why you may hear it said that only one about one-tenth of a floating iceberg is above the water.

One of the joys of winter on your lake is the sound if ice expanding. It is an eerie sound, a bit disconcerting if you happen to be on the lake at the time. Often while skating I have heard and seen an expansion crack sizzle right past me and off into the distance. If you can take having a window open on a very cold, still night, try lying in bed and listening to the ice boom. I guess it’s winter’s version of listening to the loons call.

The Ice Cometh: How much weight can it hold?

When I was a kid, I went with a brother and a couple of friends down to our local river on a cold December Sunday morning. We found the river (actually at that place an estuary, its water level determined by Lake Michigan) frozen clear as glass.

We first thought of skating – but was the ice thick enough? We dropped a couple softball-sized stones from the bridge and, instead of breaking through, each landed with a solid thock! That sent us scrambling down the embankment to the water. One by one, we inched out from shore, the water under the ice less than a foot deep. We kept inching farther, staying well apart, still over shallow water. A few stress cracks showed the ice to be about two inches thick. Mustering our courage, we each tried jumping and landing hard. The ice held firm. Then we moved together into a circle and jumped in unison. Still no sign of weakness.

We ended up skating (with parents’ permission) for hours that day, on ice so clear we could see every detail on the bottom, two to four feet down. But were we really safe? Just how strong is ice? How thick does it have to be to walk on, skate on, drive a car on? I grew up with an old saying, allegedly from someone’s grandfather, that “Two inches of ice will hold a team of horses.” Every authoritative source I’ve read lately contradicts that.

Any discussion of when ice is “safe” must account for the possibility of springs, flowing water underneath (as on a river), snow on top, objects like logs or rocks protruding, recent temperature changes (have there been any freezing/thawing cycles?) and the condition of the ice itself (late-winter ice that is honeycombed is notoriously hazardous). Most experts will tell you there is no such thing as “safe” ice – venturing out is always at your own risk.

Even when we’re talking about clear blue ice – the kind formed from calm, very cold nights – authorities disagree on how much ice is acceptable. Some say to stay off ice three inches or less in thickness. Others say less than two inches will do in some circumstances. I have skated on river ice barely two inches thick. It was creaky, but I didn’t worry too much because I stayed near the bank, over water no more than a foot or two deep. If the ice broke I would at worst end up with cold and very wet feet and lower legs, and the river was right behind my house, so a warming place was nearby.

I won’t be so casual venturing out onto Birch Lake, where the depth just a few dozen yards from our shore drops to eight feet and more. If you’re looking for a little guidance on ice safety, here are a couple of perspectives from knowledgeable sources. The Lincoln (Neb.) Fire and Rescue dive and water rescue team gives this advice:

·        Less than 3 inches: Keep off

·        4-5 inches: Ice fishing and skating (person up to 250 pounds)

·        6-7 inches: Snowmobile or ATV (1,100 pounds)

·        8-11 inches: Light car or truck (3,500 pounds)

·        12-14 inches: Medium truck (8,000 pounds)

The U.S. Army Corps of Engineers breaks it down this way:

·        Less than 1.75 inches: Keep off

·        1.75 inches: One person on skis

·        2 inches: One person on foot or skates

·        3 inches: One snowmobile or a group of people walking single file

·        7 inches: Automobile

·        8 inches: 2.5-ton truck

·        9 inches: 3.5-ton truck

·        10 inches: 7- to 8-ton truck

This guidance applies to clear, blue, sound ice. So the old folk wisdom about the team of horses is not to be trusted. Here is an old saying you can live by:

Thick and blue, tried and true.

Thin and crispy, way too risky.

When in doubt, don't go out. 

The ice cometh: Why is it slippery?

One of my great winter joys has been ice skating – on a lake or river rather than a rink (especially an indoor rink). Nothing beat the first venture with blades onto brand new ice, barely thick enough to be safe, often clear as glass. And I’m not just talking about childhood here. As recently as 10 years ago we lived on a dammed section of river that by Thanksgiving usually had frozen solid. I would skate on it as often as I could, winding upstream through marsh and woods, until snow came and covered the ice. I am hoping one of these years our Birch Lake will freeze and stay clear of snow for at least a few days. It is fascinating to look down into a lake through sheet of ice.

Do you skate on your lake, conditions permitting? Have you ever wondered why you’re able to skate – that is, why ice is slippery? After all, the solid phases of most compounds are not. Perhaps you don’t wonder because you think you know the answer. If you’re like me, you were taught in grade school that we can skate because the pressure of the blades lowers the melting temperature (32 degrees F) at the ice surface, creating a thin film of water on which we glide. But if that’s true, why are we able to slide across ice while wearing flat-soled shoes, which exert much less intense pressure?

It turns out science has pretty well rejected the pressure explanation. In an article in the New York Times (http://www.nytimes.com/2006/02/21/science/21ice.html?pagewanted=all&_r=0) Robert Rosenberg, an emeritus professor of chemistry at Lawrence University in Appleton, Wis., explained why: “The explanation fails, he said, because the pressure-melting effect is small. A 150-pound person standing on ice wearing a pair of ice skates exerts a pressure of only 50 pounds per square inch on the ice. (A typical blade edge, which is not razor sharp, is about one-eighth of an inch wide and about 12 inches long, yielding a surface area of 1.5 square inches each or 3 square inches for two blades.) That amount of pressure lowers the melting temperature only a small amount, from 32 degrees to 31.97 degrees. Yet ice skaters can easily slip and fall at temperatures much colder.”

There are now two other explanations – apparently not mutually exclusive. One is that friction from the skate blade (or shoe) is what heats and melts the ice and creates the slipperiness. The other is that the ice surface is inherently slippery. “This argument holds that water molecules at the ice surface vibrate more, because there are no molecules above them to help hold them in place, and they thus remain an unfrozen liquid even at temperatures far below freezing,” the Times article said.

Among scientists who believe in inherent slipperiness is Dr. Gabor Somorjai at Lawrence Berkeley National Laboratory. His sophisticated tests support the theory and so does a basic observation: A person standing motionless on ice is not creating friction – yet still may easily slip and fall.

One who disputes the importance of the liquid layer is Dr. Miquel Salmeron, also of Lawrence Berkeley. The Times reports that he and colleagues dragged a device similar to a tiny phonograph needle across ice and found the friction to be “very high.” And high friction of course would generate meaningful heat.

“Dr. Salmeron said this finding indicates that while the top layer of ice may be liquid, it is too thin to contribute much to slipperiness except near the melting temperature. In his view, friction is the primary reason ice is slippery,” the Times article said.

Which theory is right? Maybe one or the other, maybe both. Scientists disagree. For all the advances in scientific knowledge, ice remains a mysterious substance. So, let’s not worry too much about the explanation. Let’s get out on the ice and slide around!

The ice cometh. Time to get to know it.

Is there any ice on your lake yet? There’s some on Birch Lake near Harshaw, Wis., where I live. It’s creeping out from the shore in ovoid shapes around the shallow inlet we call Indian Bay. I haven’t seen any ice on the main body of the lake yet, but then we haven’t seen temperatures down into the low 20s and teens, not even the overnight lows. Just give it time I guess.

Ice is a fascinating substance, and I’ll be writing about it in the next few posts. Right now the water in your lake is cooled down close to the freezing point of 32 degrees Fahrenheit (zero degrees Celsius). Or I should say, that’s the temperature at and near your lake’s the lake surface. It’s a little warmer deeper down.

Water is a peculiar compound in that it doesn’t continue getting denser as it cools. It reaches its greatest density at about 4 degrees Celsius (39 degrees Fahrenheit). And of course denser water sinks. So the water at the bottom of your lake is at around 4 degrees C, and the water at the surface is about ready to freeze. A very cold night or two will get the job done, forming a skin of ice over the surface that will thicken with more cold weather.

Here’s an interesting thought: What would happen if water and ice behaved the way most compounds do with falling temperature? That is, what if the coldest water were the densest and ice were denser still? Well, if you were to take a jar full of melted wax, and drop in a chunk of wax, that solid piece would drop to the bottom.

If water behaved that same way, ice forming at your lake’s surface from exposure to very cold air would sink. As more and more ice formed, it would continue dropping to the bottom, until after a long winter the lake most likely would be frozen solid from top to bottom. Nothing would survive the winter. In fact, deeper lakes probably would not thaw completely even through the summer.

As it is, ice floats. And the ice sheet that forms on your lake provides insulation that allows most of the water below to remain in a liquid state. So the fish, clams, turtles, frogs, snails and all sorts of macro- and microscopic life get through the winter just fine.

This anomalous density pattern is just one of many interesting properties of ice. In the next post we’ll explore why ice is slippery. You probably think you know the answer – I thought I did – but the latest scientific consensus says that answer is wrong.

The ice cometh: The hard work of freezing

In freshman high school science class my teacher led us through a simple but enlightening experiment to show the difference between water and ice. It’s worth describing as we wait for our lakes to freeze over, likely in a month or so from now.

The teacher had us half-fill two glasses with water. Into one we dropped an ice cube, and into the other an equal volume of ice water. We then recorded the temperature of the water in both glasses for half an hour.

In the glass that received the ice water, the temperature dropped instantly, but then began rising and kept doing so. In the glass that received the ice cube, the temperature dropped more slowly, but then bottomed out and stayed down as the ice melted. The teacher then asked: Which would be the better way to cool a drink on a summer day?

The answer was obvious. What the experiment illustrated was a property of water called the heat of fusion, which will soon come into play on your lake and mine. Heat of fusion for water is the amount of heat energy that has to be removed to turn it from liquid to ice.

The definition of a calorie is the heat required to raise the temperature of one gram of water by one degree Celsius. It turns out that it takes a great deal more energy to turn water into ice than simply to change its temperature. In fact, 80 calories must be removed from that one gram of water in order to freeze it – and during the process the water’s temperature doesn’t change.

This works in reverse, too: It takes 80 calories to melt a gram of ice. In other words, it takes 80 times as much energy to melt ice as to warm water by one degree; or the same energy to melt ice as to warm water from zero degrees all the way to 80 degrees Celsius.

Now, let’s think about our lakes. As the days and nights get colder, the water temperature is dropping, rather quickly. Overnight low temperatures are now routinely below the freezing point of water, which is zero degrees Celsius (32 degrees Fahrenheit). So, why don’t our lakes freeze sooner? It’s because of that heat of fusion.

The water temperature will get down near the freezing point fairly quickly, but once it does, the water must give up a very large amount of heat energy before becoming ice. Finally, as the days and nights keep getting colder, we’ll see ice crystals forming along the shore, then a skin over the shallows, and finally, after a very cold, still night, a sheet of ice over most or all of the lake.

I saw the ice go off our lake last May. This year will be my first chance to watch day to day as a lake freezes. I am looking forward to it.

Wind, leaves, needles, walleyes

If you went down to your lake yesterday, you no doubt saw its near-shore surface decorated. About noon a strong wind arose, breaking the now-tenuous bond between leaves and their twigs.

As I walked the 57 (yes, I’ve counted) steps down to Birch Lake, near Harshaw, Wis., oak leaves drifted by, sliding through the air like paper airplanes. Maple leaves spiraled down. Brown clusters of discarded white-pine needles littered the stairway. Around the pier, those same items dotted the water and lay on the bottom.

I had never fished this late in the season before – have you? It’s a beautiful way to watch the season wind down. The sun, amid gray clouds, slowly settled toward the woods. The trees to the east (mostly the oaks) still bore their colors, though less brilliantly, and more sparsely. As I anchored over my favorite reef, the wind, less energetic than earlier in the day, put what anglers call a “walleye chop” on the surface. Between my boat and shore, a musky angler drifted by, tossing a slender crankbait.

It soon became clear I had some things to learn about this late-fall fishing. The walleyes still haunted the reef, which rises to five feet below the surface, from 17 feet on the deep side and 10 or 12 toward shore. It took just a few minutes for the first walleye to grab a minnow and pull my chartreuse-topped slip bobber down. I waited to a count of 10, then yanked back on the rod and...nothing. I reeled in the minnow, still lively.

I cast out again. The bobber soon disappeared. I counted to 15...nothing. Next cast, count of 20 and...nothing. In summer a five-count was enough. These fish were behaving differently. I pictured the walleyes swimming slowly, mouthing the minnow, as if savoring before swallowing.

I learned to wait until a count of 30, or 40. I ended up with two keepers in the livewell, both lip-hooked even after the long delays. Given that much time in summer, the fish would have gulped the minnow down, the hook embedded deep in the throat, a situation to be avoided.

The lights went down on the evening, until I could barely see the bobber on the wavelets. It slid under the surface, and I waited. My basketball coach used to say always to end a practice on a made shot. I wanted to end my season with a caught fish (because, in all likelihood, this was my last outing of 2013).

I counted: 20...30...40... 45. Set! The season’s last fish – a 9-inch walleye. Lip-hooked. Released unharmed. I motored at low thottle through the semi-dark to the pier. On the way up the stairs I could half-see, half-feel, oak leaves still gliding down. The two walleyes? They'll be frozen and saved for a winter fish fry -- in memoriam.

What color are your lake’s loons now? Are they still around?

Long years ago a friend and I took our first autumn fishing trip, to a Northwoods lake we usually visited in June. As we set up on our fishing spot on a chilly mid-October morning, a bird popped up near our rowboat. It had a shape like a loon – the graceful neck, the long, pointed bill – but its colors were different, the sleek black of the head replaced by brownish gray, the spots now sparser and on a gray background.

Something told me even than that is was a loon, in its winter plumage. I’m not sure how I knew; perhaps because no other bird (in these parts anyway) has that distinctive shape, and I knew loons haunted the lake where we were fishing.

Have your lake’s loons changed their plumage? In all likelihood they have. I saw a loon in winter dress as far back as September 6, on a small wilderness lake in Wisconsin’s Northern Highland-American Legion Forest. There was a loon on our Birch Lake (near Harshaw, Wisconsin) as late as last Saturday, Oct. 5. I never got close enough in the fishing boat to see its markings; it was more skittish than loons on our lake usually are (and anyway, as ethics require, I didn’t pursue, only hoped our paths would cross close enough to allow a good look).

I’ve wondered: How exactly do loons change their plumage? It seems to happen pretty quickly. I’d seen September loons on our lake in summer attire, then that specimen on the backwoods lake decked out for winter. Well, it turns out the color changes through molting: Summer feathers fall out to reveal winter ones grown or growing in. At the same time, the loons' eyes lose their bright red and fade to brown. They also pretty much quit calling.

Neighbors here on Birch Lake have expressed concern for the remaining loon, which they say should have left by now. I suspect there is still plenty of time; there is no risk yet of the bird getting iced in, and won’t be so long as enough water remains open for a long runway. As it keeps getting colder, this loon and others will head south toward the ocean for open water and a ready food supply. Loons gather in groups during migration – as many as a hundred, or even more. That would be a sight worth seeing.

Keep an eye out for your lake’s loons – if not gone already, they soon will be. They won’t start their journey back until February or March, and they’ll time their arrival here for just after ice-out. They’ll be dressed for summer – wedding attire.

Closing time

This season for me begins the fulfillment of a dream: To spend an entire year on a Northwoods lake. Of course, this is now our one and only home, so with luck that year will turn into many. For now we enjoy the magic of peak fall color reflected in water.

Do you live at your lake? Stay for the summer? Visit for the occasional week or weekend? Until this year I had never been here in the north to experience the slow turn toward winter. Right now we’re on the brink. Have you seen your lake this way? We’re torn between carving out a few more fishing days and giving up, pulling in the pier and buttoning the boat up for storage.

Recent evenings it has been mesmerizing to watch a slip bobber float on a gently undulating palette of reflected oranges, yellows and reds. Such evenings now are numbered. Yesterday I took the last dozen minnows, anchored the boat on a favorite reef, and tried once more for the walleyes and smallmouth bass that haunt the rocks. The sky threatened. Wind poked through my fleece jacket. Waves tossed my bobber around. Nothing bit. This could be the time when the fish retreat to the depths and become harder to find. Or a few more warm days could intervene and change the pattern.

Back at the pier, the boat tied off, I sat on our bench and scanned the shore. The trees lining the lake had taken longer to turn than those at the top of our hillside, but now they blazed, especially when for a few interludes the sun pierced the gray sky. Years ago my father, returning from two weeks in Norway, said that so much beauty, seen everywhere, brought a kind of fatigue. I feel that way now, not just viewing fall’s majesty but surrounded by it, immersed in it, splashes of brilliance outside our every window, around every bend in the road, arcing over our narrow private road and the town roads I travel on bicycle. It is fleeting, I know. We are just a few days, or a frigid night, or a strong wind, from lights out, the trees suddenly bare, the ground a colored kaleidoscope for a few days, then brown.

So if you are visiting your lake now, even if you have been through all this before, get out and see it. Autumn is closing down. Winter closing in.

Overnight low: 31 F

This time of year we start seeing boats put into storage, piers pulled out, cottage piping drained and windows shuttered. And yet it’s possibly the most beautiful time to be out on your lake. Not swimming in it, mind you, but on it or looking out over it.

This time of year, we see outdoor enthusiasts packing the fishing gear away and pulling out the shotguns, the grouse guns, the deer rifles. Yet it’s still a great time for fishing. A sense of urgency pervades the underwater world. Muskies, walleyes and bass are feeding heavily for the winter. It’s the time of big baits for big appetites. Last week on Birch Lake near Harshaw, Wisconsin, where I live, I caught a 7-inch smallmouth bass on a 5-inch walleye sucker minnow. Imagine what the muskies are eating.

I ignored this morning’s near-freezing temperature and went fishing for a while, parking the boat above a favorite rock bar. The 20-inch smallmouth I caught wasn’t the highlight – that was the general sense of urgency to be felt all around. Urgency for me because the remaining fishing days are few (and I am not a hunter). And urgency for the wild things. I saw ducks stopping by on their migrations. Seagulls swooping down to pluck something or other from the water. And above, a vee of geese. I heard their calls but had to scan the sky to locate them, very high, straight over my head, against cottony clouds.

There’s a narrow window between now and winter, a window quickly closing. Within two weeks, maybe three, the leaves will flare, fade to brown, and blow away. The air's crispness will give way to bite, and November's winds will turn vicious.

So now is the time to be with your lake. Pick a warm autumn day and take a long, slow boat ride. Soak some minnows in a favorite fishing spot. Take a cup of coffee or hot cider,  sit on the pier bench you will soon take down, scan the shorelines and enjoy the colors of the trees reflected in still water. Enjoy the lake while you can. Make a few more memories. Winter’s on the way, and winters here are long.

The air down there

I once told friends how a fishing pal and I spent an August morning catching bluegills in 60 feet of water on a lake in Waukesha County, Wis. The fact is we were floating in a boat above water 60 feet deep, but there was no way the bluegills were down there on the bottom. What happened was that bluegills suspended about 15 feet down were catching our baits as they fell. We only thought we were pulling them out of the depths.

How do I now know this is true? Because there was no way those bluegills could have lived that deep under the surface. And why? Because there was no air down there – or more properly, not enough oxygen.

In a previous post I wrote about how lakes thermally stratify in summer – a layer of lighter, warm water on top, and a layer of denser, cold water below. The difference in density is enough so that the two layers don’t mix very much. And as a result the lower, cold layer becomes very deficient in oxygen, more and more so as summer wears on. That upper layer (called the epilimnion) gets recharged with oxygen daily and the wind kicks up waves, or just through normal diffusion. The lower layer (the hypolimnion), of course has no access to the surface, so no way of getting recharges, and meanwhile its oxygen gets steadily used up.

Algae, dead plant matter, dead fish, and all manner of organic material sink to the bottom throughout the summer. There, it is broken down by aerobic bacteria – the kind that need oxygen to live. Gradually, the amount of oxygen dissolved in the water decreases, until there is too little to support fish or much of any kind of life. The depletion may become so extreme that the job of breaking down dead matter falls to anaerobic bacteria, which exist without oxygen. So that zone toward the bottom of the lake becomes almost a dead zone – a hostile place.

This is one reason why summer anglers are cautioned not to “fish too deep.” If you drop a bait beyond the upper, oxygen-charged layer, into the lower, oxygen-poor zone, you might as well be fishing on the moon. There’s a thin zone between the two layers (sort of like the thin layer of peanut butter in a sandwich) where the temperature changes rapidly, from warm to cool. This is called the thermocline, and fish will stay at or above it – they have no choice. The bluegills my pal and I were catching that August day in all likelihood were sitting at the thermocline.

Of course, lakes do not remain stratified. At this time of year, as the days and nights cool, so does that surface water. The epilimnion gets steadily cooler and thinner, until finally the whole lake temperature equalizes, at which point the wind can stir things up, adding life-giving oxygen throughout. This is called the fall turnover. You can actually see this happen on your lake as the water all of a sudden becomes cloudy, as the dirtier water from below mixes with the cleaner water from above. You might even notice a hint of sulfurous smell – the result of hydrogen sulfide (“marsh gas”) produced by those anaerobic bacteria in the depths as they fed on dead material through the late summer.

The turnover on our lakes here in northern Wisconsin is happening about now. It’s a rite of autumn, as inevitable as the oaks and maples turning color.

Is everyone a fisheries expert?

Are you satisfied with the fishing on your lake? Is it as good as it used to be? Is there talk about a need to stock more fish? Or change bag and size limits?

Many lake associations and friends groups want to improve the fishing, and that is certainly the case here on Birch Lake, near Harshaw, Wis., where I live. Here, the fishing most certainly is not what it used to be. Years ago, this was, in the words of one long-time cottage owner, a “dummy lake,” meaning any dummy could catch fish. Bluegills and crappies abounded. Perch could be caught at will. Walleyes grew to trophy sizes. Largemouth bass and northern pike were available, as were muskies.

Then about a dozen years ago, rusty crayfish invaded and mowed down the cabbage weed beds that created much of the fish habitat. Fishing was bleak for a few years until the lake Friends group began trapping the crayfish, smallmouth bass moved in, and they and other fish began feeding on the invaders. Now we have trophy smallmouths, abundant walleyes, (though on the small side), and a good musky population, but panfish are about nonexistent. People long for the old days, as do I, since my family vacationed here for about 20 years and we saw the before and after of the crayfish explosion.

At meetings of Friends of Birch Lake, someone almost inevitably brings up the fishery and how we can improve it. The group has placed a couple dozen cribs in recent years, five last year alone. Some members want to petition the DNR for a special walleye regulation that would let us keep fish below the statewide legal size limit of 15 inches. Others want the DNR to stock fish here. The latest idea to surface, in the newsletter of the Friends group (of which I am treasurer), is to have people start keeping (instead of catching and releasing) smallmouth bass. The thought is: The bass are abundant and we need to “balance the species.”

Now, this informal fishery management practice has no scientific foundation – no lake survey, no assessment by an aquatic biologist. I am fully sensitive to the concern about the lake and its fishery. I’ve had ideas of my own on how to improve things. But I must admit my ideas have no more scientific merit than anyone else’s, so I have largely kept them quiet. I might suggest that, if we can afford it, our Friends group commission a lake study by an independent biologist. Then we might know where the fishery stands and be able to propose changes that have a reasonable chance of success.

In the meantime, I am going to release smallmouth bass – anything that eats rusty crayfish is my friend. In fact, I imagine most other anglers feel the same. Anyway, the catch-and-release ethic is strong, and most would be about as likely to start keeping bass as to quit brushing their teeth.

The point is that we all care about our lakes and the fisheries, and we’re all willing to invest time and to some extent money to make them better – but we need to build our actions on a foundation of knowledge. If we do just a little research, we find that stocking fish is rarely a long-term solution. Lakes prove out Aldo Leopold’s findings about carrying capacity: It’s habitat that decides which fish species thrive and in what numbers and sizes. We also find that usually cribs do more to concentrate fish already there than to expand their populations. And we find that tinkering with size and bag limits and changing the catch-and-release ethic are at best exercises in guesswork, unless we know through research what we’re doing.

So if we care as deeply about our lakes as we claim to, perhaps we need to put our money where our passions are and learn what’s happening under the water before we start trying to change things to suit our wishes.

What’s the rush?

I call them “pencil reeds.” That’s because they grow sticking straight up out of the water like, well, pencils. When I was a kid, my dad called them reeds. On the lake where we vacationed, he would row us through a patch of them and let each of us pluck one to trail in the water.

I now know they aren’t reeds at all, but rushes. I also know they hold fish. If I’m fishing on an unfamiliar lake and see “pencil reeds” along a stretch of shoreline, or better yet, away from shore, that’s a place I’m going to try. They grow in shallow water, but bass, panfish and sometimes northern pike haunt them regularly.

Hardstem and softstem bulrushes are common here in northern Wisconsin, and in fact there’s a bed of what I believe to be hardstem right next to our pier. In fact, by mid- summer, they grow up between the pier boards and I need to give them a haircut. Some people along our shoreline have dug the rushes out to expose the sand bottom for swimming.  I’ve mainly left them along because of the shelter they provide for young fish; I often see schools of perch and smallmouth bass fry in “our” rush beds.

These rush beds typically aren’t too dense, so when fishing one is tempted to cast a lure deep into them to tempt a big fish holding in the cover. When I try it, I usually regret it. On the retrieve a treble hook is all but sure to snag a rush, and it’s difficult to pull it out of the tough, fibrous stalk. That means paddling or trolling-motoring over to extract the lure by hand.

Do  “pencil reeds” grow on your lake? If so, test them for their fish-holding potential. And note that snorkeling through them or along a bed’s edges can bring you lots of fish sightings.

How clear is your lake?

Is you lake clearer than the next one over? Clearer than the one where your best friends live? Maybe the questions don’t matter to you, but water clarity is one attribute people think of when judging the quality of a lake. So how do you find out whose lake is clearer? You could get a qualitative judgment by slipping on fins, a mask and a snorkel and kicking your way around both for a while, eyes down. Or you could get hold of an electronic turbidity meter and scan a test-tube sample taken from each lake.

Of course, there’s a middle ground, and that’s to make yourself a Secchi disk. It’s a very simple tool for measuring lake water clarity with reasonable accuracy, and it’s really quite a bit of fun to use. Secchi disks (pronounced SEKK-ee) are accurate enough so that freshwater biologists often use them for their water clarity measurements. Look at a Department of Natural Resources report on fish stocking for a lake and you’re likely to find a Secchi disk reading.

A Secchi disk is simply a circular, plate-like object on a rope that’s painted with quadrants, like a pie cut in four pieces. Two quadrants are white, the other two black. To use the disk, you go out in a boat to where the water is deep, then lower the disk slowly, slowly, until you can no longer see it. Mark the rope at the waterline. Then slowly, slowly, pull the disk up until you can see it again. Once more, mark the rope at the waterline. Now retrieve the disk and measure the distance from the disk to both marks. Take the average, and that’s your Secchi disk reading.

What the Secchi disk actually measures is how deep light penetrates into the water. Suppose your Secchi disk disappears at 10 feet below the surface. How deep does the light penetrate? That's easy, right? Ten feet. Ah, but no! The light you see bouncing back from the disk actually has to make a round trip, from the surface and back up to your eyes. So a Secchi reading of 10 feet means light penetrates to a depth of about 20 feet. 

A Secchi disk is quite easy to make. On the Internet, you can easily search up instructions on how to make a one good enough that a biologist would be happy to use it. Since you don’t need one good enough to sell in a scientific supply catalog, all you really need is a round object, a weight to make it sink, a drill to bore a hole in it, a length of rope, and a couple of cans of paint (ideally waterproof).

As long as you can get the disk to stay face up as you lower it, it’s good enough for your purposes. Try making one and checking your lake water clarity – not just once but at different times of year, including winter, through the ice. Keep a record of Secchi disk readings in your home or cabin log. You’ll enjoy it, and chances are the kids will love it.

In the middle of nowhere

I often hear lake home and cottage owners say, “My lake is no good for fishing.” In fact, I heard such a person say that about an Upper Peninsula Michigan lake that is my all-time favorite and rarely if ever lets me down. Maybe people who say that are just using the old angler’s trick of keeping the mouth shut about a good spot. Or maybe they haven’t discovered the magic of something called the mid-lake hump.

Serious fisherman know about humps, of course. They’re also known as bars, reefs, or sunken islands. Call them what you will, they hold fish. If you see a boat parked out on your lake, away from shore, seemingly in the middle of nowhere, chances are that angler is working a hump. Novice fishermen, and even long-timers who never got serious, tend to fish along the shore, in the lily pads, around piers, or in fallen timber. Wisconsin guide and lure-maker Joe Bucher calls that tactic “bank beating.”

You can find fish in the shallows, of course, especially at early-season spawning time. But more often you’ll find more and bigger fish around deeper-water features, and one such feature is the mid-lake hump. How do you find humps? The easiest way to start is to buy a topographic map of your lake that shows the depths. That will give you the approximate locations of spots to try. If no map of your lake exists, then you have to go exploring. One good place to look is in an area well away from shore where you’ve seen people fishing.

With or without a map, you can pinpoint humps by prowling around slowly with your depth finder (fish locator) running. Before I owned one of those devices, I would find humps by rowing or motoring slowly with the anchor hanging down about 15 or 20 feet. When it hits a hump, you’ll know.

How do you fish a hump? It’s not difficult. You fish pretty much the way you would in a near-shore area. If the hump is shallow (say, five or six feet), you can cast spinners. If a little deeper (maybe 10 to 12 feet), throw deep-running crankbaits. Or in either case, you can hop jigs along the bottom, or cast slip-bobber rigs.

How good are humps? So good that once you know about them, you may give up “bank beating” for good. Just last month, on a small lake near our home (no, I’m not telling which one), I worked a hump I’ve known about for some 25 years. This hump, about 100 yards from the nearest shore, rises from 20 feet of water up to seven feet.

While people in three other boats worked the wood along shore, I anchored on the hump and cast leeches on a slip-bobber rig. In about three hours, I caught 12 smallmouth bass, plus 10 walleyes – eight of them easily legal size, and two of them well over 20 inches. I released all the bass and kept three of the smaller walleyes, which are now in my freezer awaiting a special occasion.

If you’ve been mostly a “bank beater” on your lake, try taking a day to find yourself a mid-lake hump. Once you do, you have a great place to take your kids. And you might never again have cause to say, “My lake is no good for fishing.”

People tell us we’re lucky. I’m still not sure if we are.

Do you live on your lake? Or own a cottage that you visit for weekends and vacations? Or rent a cabin you come back to for a week, year after year? Your status no doubt affects the way you look at your lake and lake life.

Right now it’s Labor Day weekend, the last big hurrah for the part-timers here at Birch Lake near Harshaw, Wisconsin. Of 80 or so places on our lake, maybe 10 are full-time homes, the rest weekend and vacation retreats. This weekend, everyone is here. Yesterday cars, pickups and SUVs streamed down the private road on which we live (“streamed” being a relative term, perhaps eight or 10 vehicles last afternoon and evening, which means twice as many vehicles as there are cottages on the road between our place and the dead end).

We used to be cabin renters. Now we live here full-time. And the change in our perspective is dramatic. Before, we might have been among those weekenders, arriving on Friday night after work, the car crammed with kids, dog, duffel bags, water toys, fishing gear, books, groceries, all of us looking forward to a few days on the water, the last few days before we face a long winter. Leaving on Monday would mean facing the reality of not seeking this lake again for several months.

Now, while glad to see our (part-time) neighbors and wanting to get to know them better, we also see this weekend as the last spell of noise before the lake quiets down. In the evenings there will be lakefront parties, music throbbing from outdoor speakers, fires crackling. After dark there will be fireworks (not the organized, authorized kind, but explosions and flashes from various spontaneous private displays).

If the weather is warm (and it appears that will be the case), there will be speedboats, JetSkis and water skiers out much of the day, maybe even up to sunset and beyond, which means into the prime fishing hours. And as for that, I’ll have more competition for the prime fishing spots on the reef along the lake’s northeast shore.

All this, too, is relative, since even at its busiest our little 180-acre lake is pretty sedate, not at all like the lakes in the epicenter of the tourist town of Minocqua a dozen or so miles north. Still, while before we would have wanted this three-day weekend to last, now in large part we’ll be glad when it’s over, because then the lake will truly quiet. When summer has gone, when people have used up their vacations, when the kids are back in school, there’s almost no one up here. We have the lake essentially to ourselves.

There are those who envy us. At the lake association picnic last month, when we told neighbors we had moved here, the usual response was, “You’re lucky.” For the most part it seems, those with lake places who do not live here wish they did, and hope one day they will. We have come face to face with the reality of full-time Northwoods life, and I am not yet certain how, in the long run, we will like it.

I still work for a living (though now just four days a week, not five). And life as a full-time resident is far different from life as a tourist. You move, and you discover that, up here, there are still only 24 hours in a day – imagine that! So the hiking, biking, fishing, car touring, shopping (my wife’s favorite) and all the fun still have to fit in around work, exercising, cooking, cleaning, and work around the property (which for us no longer includes mowing lawn). To paraphrase an old saying: Before moving north, cut wood and carry water. After moving north, cut wood and carry water (and move lots of snow).

So we will see how all this plays out. Right now we do feel lucky, especially with autumn coming, the bracing cool days, the spectacular color of the oaks and maples on our place, around the lake, and down every road – and the wonderful thought of not having to take leave, with all the pain that once entailed. We’ll enjoy it now and not worry too much about whether, two or five or ten years from now, we will still feel lucky.

The ring of life

You know your lake is rich in living things – but the land immediately around it is, too, especially is it’s left natural versus being planted to lawn.

I heard an incredible presentation on this subject at the 2013 Wisconsin Lakes Convention in Green Bay. John Haack, natural resource educator with the University of Wisconsin Extension, talked about “Animal neighbors,” focusing on the 30-foot zone of land around a lakeshore.

Perhaps not coincidentally, 30 feet is with width of the so-called “no cut” zone where shoreland zoning laws and regulations say vegetation is not to be removed. The idea is to preserve the scenic value of the lakeshore as seen from the water, and to protect the abundance of near-shore life.

Haack’s presentation was full of insights about creatures “Cute, slimy, spooky and beautiful,” to use his words, that I had never heard of or did not closely associate with water. Cute? How about the water shrew, a tiny mammal actually able to run on the surface of the water and dive under it.

Slimy? Salamanders, which spend a major part of their lifecycle in water and emerge to make homes in moist places, like under fallen logs.

Spooky? Bats make their homes near the water, coming out at night to hunt for insects (and occasionally echo-locate their way into collisions with my fishing line or slip bobbers).

Beautiful? Loons, of course. They nest right at the water’s edge. And dragonflies qualify as beautiful, although some may put them in a “creepy” category. Next time you head down to your lake, give a moment’s thought to the 30-foot zone of life you pass through and make yourself a promise to take special care of it.

Your lake has “fleas” – and that’s a good thing

What might be the most important living thing in your lake is a tiny organism you probably have never seen, at least up close.

Daphnia, often called water fleas, are an essential food source for fish fry as well as for water insects and the immature forms of frogs, toads and salamanders. Creatures that eat the Daphnia become food for larger and larger fish – ultimately the perch, walleye, bluegills and others that grace your dinner table. So a healthy Daphnia population is critical to your lake’s ecosystem.

In reality, Daphnia are not fleas at all. They’re called fleas because their herky-jerky swimming patterns remind observers of the jumping of fleas. Daphnia are actually crustaceans, related to crayfish and shrimp. You don’t need a microscope to see them – the ones in your lake are probably about a millimeter in size or somewhat bigger. So if you scooped up lake water in a fruit jar and looked through it, you’d probably see a Daphnia or two kicking about.

Of course, they look much more interesting under magnification, with their translucent (actually almost transparent) shell, called a carapace. Through this you can see the innards – include a green gullet if the specimen you’re observing has just eaten its fill of algae. The heart lies just behind the head and beats roughly 180 times a minute – about three times as fast as the heart of a healthy human at rest. Under a microscope, you can watch the heart beat, watch blood corpuscles pass through the circulatory system, and even see unborn Daphnia moving in the brood pouch.

Daphnia have helmet-shaped heads that sprout long antennae, which they use (believe it or not) for swimming. A downward thrust of the antennae propels the creature upward; it then floats back down, on the way breathing and collecting food. Steady movement of the 10 legs creates a current that moves food into the digestive tract. Besides algae, Daphnia eat bacteria and protozoans (one-celled animals).

Daphnia generally undergo parthenogenetic reproduction – offspring develop from unfertilized eggs. Once hatched, the young molt (shed their shells) several times before becoming adults.

Now that you know a little about water fleas, be aware of them when you swim and fish in your lake. And don’t worry that they will infest your dog (because, of course, they are not fleas). You can see lots of cool pictures of a Daphnia at http://images.search.yahoo.com/search/images?_adv_prop=image&fr=altavista&sz=all&va=daphnia.