Sunday, December 14, 2014

Travels etched in snow

All spring, summer and fall, animals come and go across our woodland and lakefront properties, but we barely notice because they leave little evidence.

In winter, though we easily see their tracks in the snow. Your snow-covered lake is a great place to track wildlife: The trails traverse open space instead of weaving among trees and brush.

The only trouble with winter tracking is that it can be hard to identify the actual prints. The animals’ footfalls don’t leave clear impressions in powdery snow the way they would in mud or soft sand. You need to go by clues such as the track pattern, the sizes of the impressions, and the spacing of the prints.

The New Hampshire Fish and Game Department offers a free “Pocket Guide to Animal Tracks” (http://www.wildlife.state.nh.us/Wildlife/Wildlife_PDFs/Track_Card.pdf). Its detailed images of the various prints won’t help you as much in winter as in other seasons, but the guide does include the types of track pattern and the typical print sizes.

Anyway, an essential step in tracking winter wildlife is knowing who is out and about. For example, you won’t find bear tracks in snow, since the bears are denned up until spring. Beavers don’t hibernate but typically store enough food underwater to get them through the winter, so they’re not seen very often.

So how can you identify those trails in the snow? The New Hampshire guide identifies four basic track patterns. First are the hoppers, chiefly squirrels and rabbits. Squirrels leave roughly box-shaped sets of tracks, a larger pair (the hind paws) toward the front in the direction of travel. At each hop, the front paws land first, and the rear paws leapfrog past them. Rabbit track sets are similar except that the front paws fall one behind the other instead of side by side.

Then there are tracks that proceed in a nearly straight line. Foxes, coyotes, bobcats and deer share this pattern. Deer hooves commonly exert enough pressure to leave well-defined cloven marks in the snow. As for foxes and coyotes, absent clear paw impressions, track spacing can help you tell the difference: 14 to 16 inches for red foxes, 19 to 21 inches for coyotes.

Raccoons, porcupines, opossums, skunks and muskrats leave pair of tracks, one behind the other. The sizes can help you differentiate. Otters, fishers, minks and weasels leave pairs of prints side by side (and otters, as mentioned last week, leave their unmistakable slide marks).


The recent thaw has eliminated much of the tracking snow on the lakes, but more snow will come. Consider heading out (when convinced that the ice is safe) and trying to determine just who made all those trails in the snow.

Sunday, December 7, 2014

Just you and the otter

If you live on a lake, one of winter’s pleasures is walking the snow-covered ice, until the snow gets too deep, after which you can walk it on snowshoes.

You soon find you’re not the only one who takes these walks – animals will have left their tracks before you. Imagine about six inches of snow on the ice and a soft snow falling, a couple of inches of new powder already down, as you embark in your insulated boots.

You stay close to shore, because it’s a bit too early in the season to trust the open ice, but also because this is where you’ll find most of the hoof and paw prints. Now and then an animal will shortcut across a bay, or across the lake proper, but mostly the tracks hug the shoreline, food and cover close by.

Not far on your walk, you come upon sausage-shaped depressions in the snow, each six to eight feet long, paw prints between. These are the slide marks of otters. You know they’re fresh because they remain well defined, the edges not even slightly softened by the falling snow.

You may not like assigning human qualities to animals, but when it comes to otters, you can’t helping thinking that here are creatures who know how to have fun. They don’t walk or trot along – they run and slide. Yes, they take a few running steps, then flop on their bellies and glide over the snow. A few more steps and glide again.

And so it goes, the tracks continuing as you walk along. The paw prints’ orientation shows you and the otter are heading in the same direction. You keep your eyes forward, hoping to catch a glimpse, since these marks can’t be more than a few minutes old. Here and there the trail heads up into the woods, then emerges again on the ice.


You never see the otter, just follow its trail halfway around the lake to where it finally enters and stays in the woods. On this day, the new snow has cleared the lake’s slate; the only tracks in evidence are yours and the otter’s. You’re glad to have shared the moment.

Sunday, November 30, 2014

The lid goes on

If you wonder what happens in your lake after the ice forms, the answer is: Not a great deal. Sure, fish still bite, some more readily than others (bass being among the reluctant).

But in general, things get quiet, still and dark down there under that translucent, snow-covered sheet. The three inputs that make your lake so very much alive in high summer – light, heat and oxygen – are much less abundant.

Only cold-blooded creatures spend winter in the water (though foraging otters may come and go through near-shore holes in the ice). In temperatures not much above freezing, fish move around sluggishly; reptiles and amphibians stay mostly still or outright hibernate. Aquatic insects winter in the bottom sediments.

Except to the extent that it receives inflows from a stream or groundwater springs, your lake becomes essentially a sealed container. Very little oxygen gets in. The deeper the snow cover, the less light can penetrate, and the less oxygen plants produce from photosynthesis.

And vegetative life itself is limited. The rooted aquatic plants (weeds if you will) have long since died back. The populations of plankton – the tiny critters and one-celled algae that form the base of the lake food chain – have plummeted. Whatever oxygen was dissolved in your lake’s water at the time ice formed steadily declines through the winter.

If you’re able to look through clear ice to the bottom, you may see places where occasional bubbles of gas issue from the muck and rise until they meet the ice cover. But biochemical activity and life in general slow to a crawl. For fish and other lake creatures, it becomes a question of survival until spring.

Imagine what it’s like down there, under the ice. There’s barely a sound. Maybe the noise of a roaring wind penetrates sometimes. But there’s no sound of wave action. No splashing as eagles strike carrion fish on the surface. No swirling noises as loons dive down to fish. No whine of outboard engines. Just unbroken silence.

On windless days and nights, before the snowmobile trails open, it’s a lot like that up here on the surface, too. It’s a time to treasure the quiet, to feel life’s pace slow down, to enjoy a sort of suspended animation that lasts until spring.

If it feels miraculous to see the earth burst forth with life as the weather finally turns warm, how much more so to ponder the way lake life blooms again when at long last the ice recedes.


Friday, November 14, 2014

The loons: Still here




A week ago I saw them, through the living room window, in a frame of white pine boughs and trunk, far out on the lake, in a perfect row, four white spots on deep blue.

 

I had my suspicion but reached for the binoculars to confirm, steadying by pressing one barrel against the glass. Yes, loons, even at long distance, their shapes unmistakable, slowly swimming toward me, white breast feathers lit by a low sun.

 

So, they were still here. Or maybe these were not Birch Lake’s resident loons but migrants coming south from Canada. I was surprised to see them after all the cold, in winter plumage for sure (though so far off that even at 8X magnification I couldn’t discern the colors clearly).

 

I worried for them a little, the lake’s southwest lobe largely iced over and a crust on the main lake starting to push out from shore. I have heard stories of loons getting iced in, though it does seem somehow they know enough to leave before it’s too late.

 

The fact remains, loons need a lot of space in which to take off. Just as a jet plane is marooned at an airport with a too-short runway, loons are stuck if there isn’t enough water on which to run and flap up to takeoff speed. The qualities that makes loons adept divers and hunters – short wings for streamlining underwater, and bodies less buoyant than those of other birds (solid bones instead of hollow) – are handicaps when it’s time to get airborne.

 

If loons live on your lake, you surely know the sound they make as they take flight. It’s that sound Fred Flintstone’s feet made as he ran his stone-wheeled car up to travel speed: Pat-a-pat-a-pat-a-pat-a-pat-a...And not just a few pat-a’s. Loons have to beat their webbed feet over a long distance to lift clear of the water.

 

Ducks? Startle them and they seem to leap right up, airborne in an instant. Loons, on a calm day, might need to skim 600 to 700 feet along the surface. They need less room if able to take off into a wind, which provides lift, and yes, they do aim themselves upwind if they can, without the benefit of the wind sock human pilots use. Once in the air, they fly fast, some 50 miles per hour, though their flight is energy-intensive. Soaring is out of the question; the wings must beat every second.

 

So there they were out on the lake in the middle of an Arctic cold front, in all likelihood gone by the next morning or maybe even that same evening. Anyway, I will assume so. It looks like a long, long time before they come back.

Sunday, October 12, 2014

Closing Time

I hope you were among the fortunate souls who spent last weekend at their lake homes or cabins. I met several such folks as I took a solo paddle, my last of the season, around the shoreline of Birch Lake, at Harshaw.

This was a prototype October Saturday afternoon, clear sky, temperature mid-50s, the softest of breezes, the lake’s surface smooth, oaks and birches still holding their colored leaves, the air scented like (to borrow a phrase from Garrison Keillor) fine brandy.

When traveling alone in our red Kevlar Old Town, I always assume the bow seat and paddle stern first; sitting farther amidships keeps the canoe flat instead of nose-up in the water. At this season there’s something appropriate about paddling “backwards”: The trip is more about looking back than forward.

You tend to think, as autumn closes down, on what was instead of what will be. My annual spring canoe reconnaissances are about watching for life in the shallows, spotting painted turtles released from hibernation, following smallmouth bass across the reef on the lake’s east end, spying on walleyes hunkered deep in sunken tangles of brush.

On this mid-October ride, there was of course little life to observe other than a somewhat heavier-than-usual clouding of green algae. The fish had gone deep. Several small ducks in a cluster skittered away and up well before I could get close enough for an identification.

I did encounter several lake neighbors enjoying the day in various ways: one man disassembling a pier, ratchet wrench periodically rasping; another enjoying a drink while seated atop a short stairway of timbers; a woman at the end of a pier with a small black dog that barked at me sharply; a man and wife prepping a pontoon boat for storage, two fishermen in boats working rocky points, presumably for muskies.

From here on there would be few days like this. It’s hard at such times not to regret the decline of the seasons and to long, far prematurely, for spring. It’s too soon to embrace the idea of November’s bleakness and then the long winter. So, while taking in the glory of the day, we tend to scan back over the good times of spring and summer past.

As I pulled the Old Town from the lake and tipped it over on shore, for the last time until next year, the couple from three lots down paddled by in their canoe, just two more lake country folks lucky enough to enjoy this day, around or on the water.

Saturday, October 4, 2014

This turnover isn’t for dessert

Right now many Northwoods lakes are going through (or soon will) something called the fall turnover. It’s a phenomenon as beneficial as it is interesting. 

Fall turnover is a restorative process, a bit like opening doors and window in a long-sealed, musty basement and letting lots of clean, fresh air course through.

A previous column in this space told how lakes stratify (form layers) in summer – warmer, lighter water above and colder, denser water below. At the height of the warm season, these layers don’t mix very much because the difference in density between surface water (at, say, 80 degrees F) and deep water (at, say, 40 or 45 degrees) is considerable.

So as the summer wears on, all kinds of materials sink from the surface water into that cold bottom layer. Plant parts, algae, fish carcasses, dead insects and more drift down and decompose, consuming oxygen. As a result, the oxygen down there can become quite depleted.

What would happen if your lake remained stratified all the time? Those deep waters would become largely lifeless, hospitable mainly to organisms that thrive in anaerobic (without oxygen) conditions.

But fortunately, along comes the fall turnover, generally sometime in late September or early October (likely on the early side this year because of all the chilly weather). In simple terms, what happens is that the surface water gradually cools, and the difference in density between the surface and deeper water decreases, so that eventually wind and wave action can mix the layers together. And that means the lake, from surface to bottom, becomes infused with oxygen.

This is great for all manner of lake creatures – especially fish that dwell in the depths – that need oxygen to make it through the winter.

How can you tell if your lake has turned over? Well, for one thing, the water suddenly becomes cloudier than usual because the mixing action brings up nutrients and debris from the bottom. You might even notice a hint of sulfur scent (like rotten eggs) as decomposing material comes to the surface. When the turnover is complete, the water becomes clear again, likely more so than in high summer.

Some anglers say fishing is tougher during the turnover because with oxygen available everywhere, the fish are more scattered.

Different lakes experience fall turnover in different ways. Deeper lakes take longer to turn over. Shallow lakes may not turn over at all because they never actually stratify in the first place – wave action keeps them well mixed all through summer. The turnover itself can play out in a few days in some lakes, or during a week or more in others.


So watch for signs of turnover in your lake. It’s another seasonal milestone, like ice-in and ice-out, that can be fun to track over the years.

The bounty of the benthos

Leaving an airport, you see signs that say Ground Transportation. After flying at 36,000 feet and a few hundred miles an hour, that travel mode seems quite unglamorous.

So it is with life on at the bottom of a lake, which the limnologists (freshwater biologists) call the benthos. Up above in the water column the fish are like the aircraft and birds of our dry-land world. Creatures less appreciated live on (an in) the “ground” below.

It’s appropriate at this season to think about the benthos, because that’s where a lot of lake life is heading as the water gets cold and winter comes on. The term “benthos” comes from a Greek word, “bathys,” which means “deep.” It’s a zone much richer in life than most of us appreciate.

Of course, crayfish live on the bottom, as do clams, mussels and snails. Aquatic insects like mayflies and damselflies also live on the bottom, or buried in sediment, at stages of their metamorphosis from egg, to nymph, to winged adult.

These creatures are important links in the lake food chain. They eat algae or sunken plant matter and in turn provide food for fish (as anyone who has ever caught bluegills with nymphs or perch with wigglers can attest). An assortment of worms can also be found in upper layers of bottom sand and muck.

Leopard frogs and bullfrogs become benthos dwellers in winter. They do not (as many believe) dig into the bottom – the sediment contains too little oxygen to get them through until spring. Instead, they lie on the bottom, or only partly bury themselves. Some may even swim around slowly from time to time.

Painted and snapping turtles, on the other hand, do burrow into soft lake bottom mud and hibernate. In that state, they need very little oxygen and can absorb it through exposed mucous membranes in the mouth and throat.

An important function of the small benthic creatures (the worms and inserts) is that they allow scientists to assess water quality in a lake (or stream). A researcher can take “grab samples” of the bottom sediment, sort out and identify the organisms it contains, and get a good idea how healthy the lake is.

One measure they use is species diversity. In general, the more different creatures they find, the better the water quality. Another criterion is pollution tolerance. If a bottom sample is rich in immature forms of mayflies and stoneflies, which are sensitive to pollutants, that indicates good water quality. But if only midges and worms are present, that signals polluted water.

So while we get ready to “hibernate” for the winter, it’s good to think about the importance of all those creatures spending the cold season on and under the benthic blanket.



Friday, August 29, 2014

How acid or alkaline is your lake?

A characteristic you can’t see or feel can have subtle or significant effects on life in your lake. It’s called pH, and it’s a measure of how acid or alkaline your lake’s water is.

We know that water molecules contain two atoms of hydrogen and one atom of oxygen (H2O). However, some of those molecules actually exist as positively charged hydrogen ions (H+) and negatively charged hydroxide ions (OH-).

In pure water, those ions exist in essentially equal numbers. But when chemicals are added to water, the balance can shift in one direction or the other. A solution with more hydrogen ions is acidic; a solution with more hydroxide ions is basic, or alkaline.

pH is measured on a scale from zero (extremely acidic) to 14 (extremely alkaline). Pure water, which is considered neutral, has a pH of 7. Relating this to common substances, lemon juice is a fairly strong acid (pH just over 2), while household ammonia is strongly alkaline (pH about 12).

Lake waters are not that strongly acidic or alkaline. Their pH falls generally in a range from about 6 to 8, close to neutral. Interestingly enough, natural rainwater is fairly acidic (pH about 5.6), and air pollutants like sulfur dioxide and nitrogen oxides can lower the pH significantly – causing the harmful phenomenon of acid rain.

Fortunately, most lakes contain substances that neutralize (or “buffer”) acids, thus keeping the pH stable. One of the most important of these is calcium carbonate (limestone).

How does pH affect life in your lake? That’s complicated, but it determines how well certain fish species, plants, insects and other life forms survive and reproduce. For example, at pH below 6.5, walleye spawning is inhibited, and smallmouth bass disappear below pH 5.5.

pH can also determine the extent to which certain pollutants are released into the water from sediments in the lake bottom. For example, a change in pH can cause more phosphorus to dissolve in water, making it available to feed algae. In addition, many scientists believe that higher acidity is related to the release of toxic mercury into lake water. The mercury then can accumulate in fish.


pH and its effect on lake life is a complex subject. In healthy lakes, the effects are mostly subtle – pH is just one of many qualities that make each lake unique.

Sunday, August 10, 2014

Who decides where the school goes?

Hundreds of perch schooled off our pier last week. The problem? They were an inch and a half long, which means nano hooks, water flea bait, very sharp filet knife.

Looking down at that swarm of black-striped fry, moving in unison, I couldn’t help wondering: What holds that school together? Why are they schooled in the first place? And which fish decides where the school goes?

The first thing to appreciate is that these fish don’t “decide” anything. They don’t form the school out of conscious strategic thinking. The behavior is built into their genes; it conveys certain evolutionary advantages that promote survival.

First off, it’s easier for a predator to track down and capture a solitary fish than to eat fish in a school. This seems counter-intuitive, since we’d think attacking a school would amount to the proverbial “shooting fish in a barrel.” However, scientists have found that a school confuses predators. A school moving together, the sides of multiple small fish flashing in sunlight, can appear to a predator as one large fish, discouraging attack. In addition, the sheer numbers of fish in a school disorient predators, making it hard for them to zero in on one individual.

Another advantage to schooling is that more eyes watching means greater ability to find food. Schooling also helps fish conserve energy – in effect they’re able to draft on each other. The principle is the same employed by bicycle racers, one closely following another to reduce wind resistance.

But how does a school of fish move as one? According to an article on the North Carolina Aquariums website, “Each fish maintains an exact spacing from its neighbor. As they swim, they follow the movements of their neighbors and change their course in unison. Vision is the primary sense used to hold their place in a school. Visual markers play a big role – each member of a school follows some key feature of the fish around it, usually a stripe or spot on their bodies, fins or tails. The vibration-detecting lateral line, a row of sensory cells that runs along the sides of the body, also provides information about neighbors’ movements.”


A closer look at the school of perch off our pier showed the individual fish contentedly picking off white specks in the water – likely Daphnia (water fleas) or some other zooplankton. Those of us here on Birch Lake can only hope the schooling behavior helps those perch grow to catchable, edible size. Time will tell.

Sunday, July 27, 2014

The functions of fins

The fins on flashy 1950s cars were, practically speaking, useless appendages, all style and no substance. The fins on fish, though, are a different matter.

Fins may add to fishes’ beauty – take for example the “sail” on a marlin – but they are also highly functional, as essential as arms and legs are to us humans.

So, what exactly do these fins do? Let’s start with the tail fin, or what the scientists call the caudal fin. It’s mainly for propulsion. If the fish’s muscles are the engine, then the tail fin is the propeller. A few whips of the tail and the fish can be off in a flash, chasing prey or fleeing a predator. The tail fin also contributes to steering.

The dorsal fin, the one that runs along the top of the spine, adds stability during travel, a little bit like the centerboard on a sailboat or the fletching on an arrow. In many fish the dorsal fin also contains spines. It can lie flat or be unfurled, spines vertical.

The expanded dorsal fin can help protect a fish by making it appear, to a predator, larger than it actually is. The spines themselves can also deter attacks. If you’ve ever been “speared” while unhooking a perch, imagine how that would feel to the inside of a larger fish’s mouth. The anal fin, on the fish’s underside forward of the tail, also lends stability.

Deep-bodied fish, like bluegills or crappies, generally have larger dorsal and anal fins because they need more support to hold themselves upright.

Pelvic fins, on the underside coming off the belly, also help the fish stay level, providing stability against rolling from side to side. The pectoral fins, generally on the side of the fish just behind the gills, add stability and help the fish maneuver and control depth. Pelvic and pectoral fins also act as brakes – when flared out they help the fish slow down and stop.

Fin sizes, shapes and configurations vary with fish species, where they live, and how they feed. If you’d like to know more, there's a great online presentation from the the Minnesota Department of Natural Resources.


Friday, July 4, 2014

Tales in the scales

Alive without breath, as cold as death
Never thirsty, ever drinking
All in mail, never clinking

The answer to this riddle from J.R.R. Tolkien’s The Hobbit is: Fish. And the “mail,” of course, refers to fish scales.

Scales are fascinating structures that can tell a great deal about the fish in your lake. By looking at scales from fish taken during test nettings, scientists can tell how old the fish are, how fast they have grown, whether they has been seriously ill or stressed, and more.

The types of fish in our area lakes are hatched with all the scales they will ever have. Scales originate from points in the fishes’ skin and overlap like shingles in a roof. They grow larger as the fish ages by adding to the outside edge. The scales show growth rings somewhat like those seen in the cross-section of a tree trunk. A difference is that while trees add just one ring per year, a fish scale may gain multiple rings in a year.

Still, each year does leave a distinct mark, especially in our climate. Because fish are cold-blooded, their growth slows significantly as they spend winter under the ice. A thicker ring, called the annulus, forms during these times.  

Scientists can learn a lot by studying these rings. For example, the distances between the annular rings reveal the approximate length of a fish at each age up to the current one. That’s because the rings are placed in proportion to the total length of the fish. So, suppose a scale from 12-inch walleye, three years old, has its first ring one-third of the distance from its focal point to the outer edge. That fish would have been four inches long at the end of its first year.

Using scales to tell the age of individual fishes, biologists can learn about the growth rate of a lake’s fish population. Because fish grow more slowly when they reach sexual maturity, scientists can use rings on scales to estimate the age at which fish began to spawn. This helps in setting fishing regulations to make sure most fish can spawn at least once before they are caught and removed.

A few other facts about scales: Fish that swim fast and live in fast-flowing water often have small scales, while fish like carp that live in slow or still water tend to have larger scales. Some fish have smaller scales toward the tail, providing more flexibility there. If a fish loses a scale, such as to injury, it grows back, all at once – so that scale will not show growth rings.



Saturday, June 28, 2014

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.


Wednesday, June 11, 2014

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.

Friday, June 6, 2014

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.


Sunday, June 1, 2014

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.


Thursday, May 22, 2014

The making of a magnet


Fisheries research today shows a powerful connection between “wood in the water" and a lake's fish populations. Trees fallen over from the bank and into the lake provide cover that protects fish fry from predators so they can grow up. How much wood is in your water?

Birch Lake, near Harshaw, where I live, is relatively barren of fallen timber, although I got to watch one specimen make the transformation from shade provider to fish haven, Just down the shore from our pier stood a tall white pine, its roots right at the waterline, its imposing trunk angled over the water at about 30 degrees from the vertical. We wondered if it ever would tip into the water -- it seemed to be defying the tug of gravity.
Well, two years ago, we got our answer. By early summer, the tree had tipped to about 45 degrees, and as I paddled by in a canoe one day I noticed a large, lengthwise crack at the base of the trunk. After a few weeks, the old pine came down, but not with a spectacular splash. It eased down, like a staccato second-hand on a watch, tick, tick, tick.  
During a couple of quiet evenings, sitting on the screen porch, I could hear the periodic cracking noises as the tree kept ticking down. Then one morning the tree lay in the water, extending out some 60 or 70 feet from shore. It was sad to see a venerable pine go down, but the plus side is that the tree now lies in what already was a fair walleye hole, just off the edge of a bed of emergent reeds, at a U-shaped dropoff that anglers like to call an inside turn. Snorkeling around the tree soon after it fell, I saw young-of-the-year smallmouth bass darting amid the twigs and still-green needles. The old pine was becoming a fish magnet. 
Of course, if we want more fish magnets on our lakes – more wood in the water – we have to do more than let nature take its course. The state Department of Natural Resources now promotes “fish sticks” – placing whole trees, or bundles of trees, in the shallows – as a fish habitat builder. Maybe if your lake isn’t rich in sunken timber along shore, it’s worth having your lake association consider a “fish sticks” project.

Sunday, May 18, 2014

Diatoms: Where lake life begins

Weeds are springing up in your lake by now, or will soon – but the most significant plant growth that’s happening is not obvious to the eye.

As the water warms and sunlight continues to penetrate deep, diatoms are proliferating. These are one-celled algae that multiply profusely in colder water, which is high in silica and nutrients that built up over the winter.

“Diatoms use silica to build their cell walls,” according to an article in Minnesota Conservation Volunteer magazine. “They grow quite rapidly and often give the water a brownish hue. Because they cannot regulate their buoyancy in water, diatoms rely on currents or wind and wave action in lakes to keep them in the lighted zone, where sunlight penetrates shallow water. In the absence of wind, waves or currents, diatoms settle to the bottom of the lake and die.”

Later in the season, other kinds of algae take over. But a few more words about diatoms are timely and appropriate. For one thing, diatoms, seen under a microscope, are incredibly beautiful – the many species exist in a variety of symmetrical shapes.

More important, diatoms are an important part of a lake’s phytoplankton – the tiny plants that float in the water and form the base of the lake’s food chain or, to put it differently, the foundation for the lake’s food web. Diatoms and other phytoplankton perform the same basic function as grasses in prairies that support grazing animals.

Just like large rooted plants, diatoms live by photosynthesis. They make their food from sunlight, carbon dioxide and nutrients; they are called primary producers. Diatoms become food for plant-eating zooplankton – small animals like Daphnia (water fleas). These in turn are eaten by smaller fish, including game fish and panfish fry, which in turn become food for larger fish – bass, walleye, northern pike.

This of course is an over-simplified description of the food web, but it illustrates how important the diatoms and other phytoplankton are. Without them the food web would collapse – there would be no fish.

Another function of diatoms is that through photosynthesis they release oxygen. In fact, the diatoms, other phytoplankton, and larger aquatic plants make a net positive contribution to the dissolved oxygen on which fish and other lake creatures depend. 

So as you watch the water lilies, cabbage weeds, bulrushes, coontail and other plants pop up in your lake this summer, give a thought to the diatoms, out there by the billions, not doing much besides floating, yet helping to make the whole lake system function.

Tuesday, May 13, 2014

How we met: Dinner Lake


I just headed north on Highway 45 from Land O’Lakes, saw a plain wooden “Dinner Lake” sign at the first side road, took a right in the direction of the arrow, and followed the signs from there. The roads twisted back into the trees, first nice smooth asphalt, then much rougher asphalt, and then a skinny, bumpy gravel road for the last quarter-mile or so. The road dipped sharply down and bent around to the right, revealing the lake, a small blue jewel in a wooded hollow. Logs lay in the water on both sides of the boat ramp, and among them small bass hung motionless. I broke a piece off a twig and tossed it onto the water; a fish darted up, took it, and spat it out.

The boat ramp was on an almost circular bay, a narrow outlet giving way to the lake proper. I couldn’t see much of the lake itself, but several bare logs jutted out from the bay’s shore – great-looking cover. I hung around for a few minutes teasing the baby bass with bits of twig, then drove away, filing the spot in memory.

The next summer I bought a used blue fiberglass canoe. On a June weekend my friend Ed and I strapped it atop my 1964 Plymouth Valiant and drove north. We tented at the National Forest campground on Lac Vieux Desert and in the morning drove over to Dinner and slid the canoe in. We immediately found smallmouth bass among the logs, more than willing to smack a floating plug. As it turned out, loggy cover nearly surrounded the lake. We caught dozens of bass, about half of them above what was then the legal size of 12 inches.

I’ve returned almost every year since, with friends or alone. In time I discovered a rocky hump just off the east shore that is productive even when fish have deserted the shorelines. It’s a quiet lake, about 150 acres, ringed by small, well-kept cottages, most occupied just sporadically. I’ve never been able to spend an evening or weekend on the lake. In the early years there was a private campground on the east shore, but that soon closed. So it’s a lake I simply fish, once a year (with rare exceptions), almost as a matter of principle. After all, I discovered it. I don’t tell many people about it. My stock comment about it is: I’ll take you there, but I won’t just tell you where it is.

How about you? Where did your romance with your favorite lake begin? How did you two meet?

Saturday, May 10, 2014

What a difference a few days make


It’s amazing how fast things change. One day your lake is an ice desert. A few days later the ice is gone, the race is on. The race to life.

The loons don’t even wait for full ice-out – soon as a suitable patch of water opens, they’re back, plying the water, calling. The lake, freed from its ice insulation, starts warming rapidly, especially when full sun hits the bottom in the shallows.

As the temperature rises, the fish spawning procession begins. It starts with northern pike, seeking out marshy areas as soon as ice melts along the shorelines. Male walleyes begin staging in rocky, gravelly shallows while the water is just a few degrees above freezing; females follow, and activity peaks as the temperature reaches the mid-40s.

Yellow perch closely follow the walleyes, spawning as the water reaches the high 40s. The females lay eggs in long, accordion-like ribbons of jelly that sink to the bottom, where males fertilize them. The egg strands may drape over plants or tree branches in the water; early-season canoeists might see them in the shallows.  

These early spawners don’t guard their eggs; the next groups of spawners do. As the water heads into the high 50s and low 60s, male largemouth and smallmouth bass start fanning out spawning beds over gravel substrate in water from a foot to several feet deep. Crappies like it a little warmer; bluegills a little warmer still.

Meanwhile, every living creature – amphibian, reptile, mollusk, insect – gets active. Sit on your deck at night and you’ll hear the frogs and toads sing. Search up “frog calls” on the Internet and you’ll easily find sites where you can listen to spring peepers, chorus frogs, mink frogs, and others, and so distinguish the individual sounds as you might instruments in an orchestra.

This is also a time to watch the migrating through – a pair of binoculars and a field guide can help you expand your vocabulary from “ducks” to buffleheads, widgeons, mergansers, teal.


There’s a current of urgency to it all: time is fleeting. These springtime weeks are a great time of year – maybe the best of times to spend with your lake.

Friday, May 2, 2014

How we met: Birch Lake

My memories of summer vacations on Duck Lake in the Upper Peninsula stayed with me and ran deep. And so I wanted to create a similar tradition with my own family, wife Noelle and kids Sonya and Todd. We tried week-long vacations at cabin resorts on Moon Lake (Duck’s neighbor in the UP) and Presque Isle Lake in far northern Vilas County, Wis. But I was looking for a place we could return to year after year, and for various reasons neither of those two quite fit.

In 1987, when Sonya was five and Todd two, we wrote to the Minocqua Chamber of Commerce for information on housekeeping cabins. Dozens of brochures came by mail; the one that appealed most was for Jung’s Birch Lake Cottages, near a place called Harshaw that we had never heard of, about a dozen miles southeast of Minocqua. We bought a week in a cabin called Bayside, sight unseen, for $400 (enough money back then to ensure, pretty well, a quality experience).

It was love at first sight. Noelle fell for the cozy two-bedroom cabin, with new furnishings, knotty pine walls and, as bonuses, a fireplace, microwave oven, and deck – in her words, “all the comforts we don’t have at home.” For me it was about the lake, 180 acres with expansive beds of cabbage weeds on the edges of which I could catch walleyes, bluegills, perch, and the occasional largemouth bass. The romance was sealed when, on our first night, I caught a 38-inch muskie right off our pier. There was a nice swimming area for the kids, and all the Northwoods icons were there -- loons, ospreys, eagles, deer, raccoons.

We visited Birch Lake for a week almost every summer thereafter, usually staying in the Lakeside cabin, right next to Bayview. Then in 2009, a wooded lot came on the market, straight across the lake from the cottages. We closed on the lot in December of that year, parked an RV trailer there, and by fall 2011 had our own cottage. The way we came to buy the land is a story in itself, for another time. Suffice it to say our relationship with Birch Lake has bloomed into something deeper and longer-lasting.


How about you? How did the romance with your favorite lake begin? How did you two meet?

One lake, many worlds

It’s easy to think of a lake as a pool of water in which to drop a fishing lure or on which to float a boat, canoe or air mattress. But your lake is really a collection of worlds, each in its own way teeming with life. There’s the water’s edge where otters prowl the sandy fringes, where deer slip out from the cover of the trees to drink, and where eagles and ospreys perch in tall pines and scan the wavelets. The air above the water is another world, of those big raptors soaring and circling; of buzzing dragonflies, silent and delicate damselflies, and flying insects of many descriptions; of mallards and mergansers arrowing overhead.

On the surface we find ducks and loons skimming; the occasional muskrat dragging strands of cattail leaves; clusters of darting black beetles; water striders floating on surface tension, propelled by oarlike legs; ephemeral mayflies with wings raised like sails; and painted and snapping turtles, snouts poking skyward, sipping the air. Beneath the surface the lake is a thin soup of microscopic plant and animal plankton, base of the food chain for fish, not just those we like to catch but for many small and secretive species we rarely see, even if we peer into their world through a glass mask while snorkeling.

The bottom sand and muck are marked with the serpentine trails of clams and mussels and speckled with the curled shells of snails and the molts of crayfish. Buried in the sediment lie an assortment of worms, along with immature forms of various flies and other insects, metamorphosing. And that’s not even counting the different zones of vegetation; the variations in bottom character (rock, gravel, sand, muck); the dropoffs, flats and mid-lake humps; or the temperature-related strata of the water itself. Or, for that matter, the way these and all the other worlds change with the seasons.


Yes, every lake is much more than what appears to the casual viewer. And every lake rewards those who look closer and deeper.

How we met: Duck Lake

Every romance story starts with how they met. How did your romance with your lake begin? My story begins with Duck Lake – I have known it since I was eight years old. It lies in the big woods of Michigan's Upper Peninsula, just over Wisconsin line from the little town of Land O' Lakes. It’s about two miles long, shaped something like a plump L with a short horizontal stroke.

A co-worker of my father owned a cabin on Duck Lake. He and his two sons took my dad, my older brother and me there for a visit on a Memorial Day weekend. It was there I saw eagles and loons for the first time, and heard the hammering of pileated woodpeckers deep in the forest. How to describe the allure of the North? The trees are taller, the white pines especially standing in majesty. The wind sounds different. Storms loom larger; thunder booms across the vast stretches of woods and water. The night woods are full of animal noises, rustles and footfalls. Loon calls ring out over the lake – what benignly demented sort of deity would create such a creature as a loon?

My family rented that cabin one or two weeks each summer until I was in my early 20s. A great fishing spot lay just a few dozen oar strokes out from the cabin. We fished there morning to dusk, two or three of us kids in each boat with mom or dad. As I grew older, I took a 14-foot wooden rowboat on fishing explorations from one end of the lake to the other. Since then I’ve fished Duck once or twice a year almost without fail and have come to know it well. The public boat landing is right next to the old cabin property; that spot in front of the cabin is still the best spot on the lake.


In future posts I’ll tell you about my other two loves, Dinner and Birch lakes. Meantime, what’s the story of your favorite lake? How did you two meet?

Bottoms up: The lake unveiled

If yours is like most lakes in the Lakeland area, you’re still waiting for ice-out. Will you be there to observe it? I had always wanted to see the thaw happen, and last year, at last, I did. It wasn’t (as I expected) a matter of observing slow changes over a number of days. In fact, it was sudden, much of the process unfolding in little more than an hour.

Did you know (I didn't until I recently did some reading) that your lake ice thaws from the bottom up? First the snow melts off the surface. Then the sun penetrates the ice and warms the water underneath. Warm air above the ice accelerates the thaw, of course, but it’s the warming water below that really does the trick.

On April 28 last year, Birch Lake was still frozen stiff. That day and the next two days were in the 70s to 80s. Then came three more days of below-freezing temperatures, rain, snow and sleet, before winter's grip finally broke. At that point, the lake ice still looked solid – we heard reports from other lakes of remaining ice up to two feet thick. Who knew how long it would be until our lake opened up?

Saturday, May 4, saw highs in the 70s, as did Sunday, and Monday, the day it finally happened.
When I visited the lake’s shore Monday morning, ice still covered all except a small area on the far north side. There had been little change (that one could see) when I left for town about 2 p.m. But when I returned around 5 p.m., about 30 percent of our lobe of the lake had cleared, the remaining ice forming an irregular pattern, like continents in an ocean.

Then, at about 6 p.m., a wind brewed up from the east and began pushing the ice away, at more than glacial speed. Sitting on our deck, I could mark with my eye a feature on an ice sheet and note its progress relative to the trunk of a tree in our woods. It was a bit like watching the minute hand on a clock, the motion barely perceptible, yet unmistakable.

Within about an hour, all the ice had blown off to the west, the stirring action of wind-driven wavelets surely speeding up the thaw at the same time. Just like that, our entire end of the lake, some 100-plus acres of it, lay fully open. By morning, the entire lake had cleared, and loons plied the water, crying out with joy.

After the longest winter or the worst spring I could remember in my 60 years, a new season had arrived. And now, at long last – after what is officially this area’s the worst winter on record – we’re about to see it happen again. And all I can say to that is: Bottoms up!

Growing to love your lake

I have three mistresses. My wife not only knows but approves. The mistresses are Wisconsin northwoods lakes, two just far enough north and one just far enough south to be spared most of the tourist noise. I've carried on affairs with each for at least 25 years, in one case for more than 50. Their names are Duck, Dinner, and Birch. My relationships with them are somewhat one-dimensional: Mostly I fish them. And yet, through the years, I weigh each visit less in fish caught than in ambience, comfort, memory. I promise not to stretch the romance metaphor too thin, but I do love these waters.

You may have a  favorite lake, or more than one -- a place where you vacationed as a child, where your family owns a cabin, where you rent a summer cottage year after year, where you go on a ritual long-weekend camping trip with friends. It's easy to love a lake, especially one you found on your own fairly early in life and have known for decades. What is love, after all, but genuine concern for someone or something outside ourselves?

What I hope to do here is help you love your lake even more -- by getting to know it intimately, as I have come to know mine. I've finally chosen one lake -- my wife and I have built a cottage there that has now become a home. So I'll share with you what I observe about my lake and what I've learned about lakes in general, through experience, observation, reading, and even lab, field and classroom study. In the process, because for all their differences lakes have much in common, you will learn about your lake and come to appreciate it more.


Saturday, February 15, 2014

The ice abides: Who’s winning the war?

While those of us in the Northwoods have shivered our way through December, January and now most of February, a silent war has been playing out on your lake, and mine, and others.

Below-zero temperatures, day after day, want to make the ice thicker, while two feet or so of light, fluffy snow wants to act like the Pink Panther’s favorite product and insulate. So, in the face of this winter’s record-challenging cold, who is winning? Is the ice steadily building or is the insulation keeping its thickness close to normal?

It turns out the answer isn’t entirely clear. Today I asked a young man at Kurt’s Island Sport Shop in Minocqua (Wis.) what ice conditions are like on the local lakes. He told me that on average the ice is about 30 inches thick. That’s a lot of ice, but not unprecedented, and as cold as it has been I wouldn’t have been surprised if it had been much thicker. Last February here on Birch Lake (near Harshaw) I went ice fishing with a friend, and we had to power-auger through more than two feel of ice to find water. Of course, last year wasn’t as cold, but there was very little snow cover.

So this year it seems the snow’s R-value is having an effect. And the snow is having other effects too. The fellow at the sport shop said there’s a heavy layer of slush beneath the surface snow. Why? According to the folks at WinterTrekking.com, slush forms on top of lake ice from overflowing water: 

"As soon as it snows on top of ice, that creates a force pushing down on the floating ice.  All ice, including perfectly safe thick ice, naturally cracks day and night, expanding and contracting with changing air temperatures. When the ice cracks, water can rush up through the cracks on top of the ice but under the insulating snow, and form slush pockets.  These slush pockets can become very broad, sometimes covering entire lakes under the snow, and they are a hazard to travelers."

And what’s the consequence? A lot of ice anglers are getting their 4-wheelers stuck on the way to their shanties. They’re learning a lesson from trout fishing writer John Gierach: "Four-wheel drive doesn‘t mean you can go anywhere. It just means you can get stuck in worse places.” And I can’t think of many worse places to get stuck than hubcap-deep in slush in the middle of some lake snowscape. So if you’re going fishing these days, a snowmobile is the best way to get to your favorite spot (if it’s too far out to reach on snowshoes).

And just wait until (if ever) all that snow starts to melt. Then we’re going to see some messy conditions on our lakes.

Thursday, January 2, 2014

The ice abides: How thick is it?

It has been cold. Very cold. For a long time. I am confident we have not seen a temperature above freezing since Thanksgiving, and now the forecast calls for 30 below zero on Sunday into Monday.

So, living on a lake as I do, I wonder: How thick is that ice? It’s not easy to find out unless you are friendly with ice fishermen. Two winters ago, when a friend came north in February to go fishing, we found the ice more than two feet thick. It’s been much colder this year, but it’s only January.

And of course there’s the matter of snow – a good insulator – on top of the ice. Just how much insulation does snow provide? It’s hard to get a good answer. One “fact” I’ve seen in several places on the Internet (though without a credible source cited) says 10 inches of fresh snow that is 7 percent water (and the rest presumably air) has about the same R-value (R-18) as a 6-inch layer of fiberglass insulation. That’s quite impressive, if true. We have at least 10 inches of snow on Birch Lake now.

Then there’s the matter of the ice itself. On the Internet I found statements (again unattributed) that ice a foot thick has an R-value of 9, “much higher than wood, newspaper, or rigid foam board.” I also found values (credible ones from university sources) for the thermal conductivity of ice. Without getting into a lot of scientific units, it turns out that ice is only about twice and thermally conductive as glass, which is a notoriously poor heat conductor.

So what does all that have to do with the thickness of this winter’s ice? Well, for the ice to get thicker, heat (such as it is) has to escape from the water immediately below the ice. To do that, it has to penetrate first the ice and then the snow. The thicker the ice, and the deeper the snow, the harder it is for that heat to escape. 

I am betting that 30 degrees below zero for a couple of days will meaningfully thicken the ice. But if you want to know how thick the ice is on your lake, you’ll likely have to talk to an ice angler. Or go out and bore a hole yourself.