Managing Established Lakes

Fish and Lake Management
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Check visibility depth and see your water color. This pond has a good plankton bloom for springtime.
Check visibility depth and see your water color. This pond has a good plankton bloom for springtime.

Several common questions consistently come across the transom at Pond Boss World Headquarters. They range from; "How do we clear up muddy water?" to "Are turtles a problem?" to "How do we make our fish grow?"

Another biggie is, "My pond leaks, how to fix it?"

One of the most common questions is, "How do we manage our existing pond?"

First, you become a fun biology-type detective. You are on the prowl, looking for clues. Then, you have to interpret those clues and make decisions. Each decision with your pond management plan has consequences beyond the obvious...I'll explain in a minute.

There are way too many misconceptions out there in pondmeister land. "We should throw the little ones back so they can grow." Wrong...most of the time.

"Let's keep the water clear." The answer is, "Nope" ...most of the time.

"We have too much underwater moss." Maybe so...maybe not.

Let's try to clear some of the muddy depths of lake management thinking.

First, set goals. Sounds trite, redundant, and even a little bit naive. It's not. Write those goals down. What do you expect from your lake? In your mind's eye, what do you see in five years? A swimming hole? Catching bass big enough to jerk the rod out of your hand? Watching the grandkids catch sunfish after sunfish off your dock? Reading a book in the shade next to the water, looking up every time there's a splash or a bird flitting from limb to limb?

What is your "it"?

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Aquatic plants can become invasive. Know the species and judge growth rates over the following weeks. Be proactive.
Aquatic plants can become invasive. Know the species and judge growth rates over the following weeks. Be proactive.

With that list of goals in hand, evaluate current circumstances. What about your pond isn't helping you achieve your goals?

That's where you look for clues. You can become proactive when you get pretty good at seeing and understanding those clues. Until then, you'll be reactive. "Proactive" in this sense means seeing your fish growth rates slowing. Or, in early spring, you see invasive species of plants getting an early start. Reactive clues are, "My fish have stopped growing." Or, "We have way too many plants. They're invading the whole pond."

Remember, your pond is dynamic, changing all the time. As you increase your influence to achieve those critical goals, that's important to understand—water quality ebbs and flows. Water volume rises and falls. Plants come and go. Fish eat each other. Some elements of habitat change... plants grow and die. Brush piles deteriorate. Fish reproduce, then they don't, based on season.

Here's your first tip, which is a big clue. The essential parts of pond and lake management are triggered by temperature. Those biological changes start with temperature. Some of those are influenced by photoperiod but are kicked into gear at the right temperature. Fish move shallow in spring when the temperature rises. Rising temperatures trigger spawning behavior. Different species of plants begin their processes at different temperatures. Cattails and filamentous algae come to life during cool temperatures compared to other species, such as the pondweeds and coontail, which become active when the temperature rises.

Track your water temperature. Write it down in a notebook, plug it into a spreadsheet-whatever suits your style. Add the date, and you'll see the temperature pattern after several years. Watch for plant growth in spring, add those notes, and compare them to the temperature. You'll see the patterns of plant growth compared to temperature. Then, next year, you can project what will happen.

Watch your fish. They'll come shallow to reproduce. You'll see bream beds in shallow water with male sunfish running around in circles, protecting eggs. For those who love Largemouth bass, watching their spawning ritual, followed in a few days by big schools of baby bass rising to the surface, is fun. You'll soon note bluegills spawning at a different temperature than bass. Redear sunfish spawn between bluegill hatches, often using the same nests.

Track that.

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Take time to measure some of your fish and judge their condition.
Take time to measure some of your fish and judge their condition.

All the while, measure and interpret the visibility of your water. When those baby fish begin hatching, they'll absorb the yolk of their egg and become what we call "swim-up fry." At that point, they have no body fat. When you think about that, those baby fish must eat immediately, or they'll starve to death...or get eaten by an underwater bug like dragonfly larvae. It's your job to provide that food. The traditional way to feed baby fish is to ensure your water has a plankton bloom. That's what you are judging when you measure visibility. Buy a Secchi disc. Use it. When your water shifts from clear to a greenish-tint and visibility decreases to two feet, your pond is providing food for newly hatched baby fish... and shading sunlight off the pond bottom, pushing back rooted plant growth. Plants need sunlight.

In the southern and southeastern parts of the nation, pond managers often fertilize their waters. In the Midwest and along much of the Atlantic seaboard, fertilization is a measured act, depending on water chemistry and climate. In northern states, most pond managers refuse to fertilize their water because of the associated risks of winterkill.

Speaking of water chemistry, if you haven't had your water analyzed, now is a good time to do that. It may mean little in the grand scheme of things, but it might mean a lot...especially if alkalinity is lower than 40 parts per million. Part of your management strategy, especially where soils are acidic, can mean adding dolomitic lime. That's your pond's Rolaids to buffer acid and keep the chemistry on an even level, minimizing stressors for those living things under water.

Lime helps stabilize the acid/base seesaw. That's a reason we measure pH, to see if it fluctuates or stays steady with all the biology happening in the water.

Add visibility depth to your database.

Now, you have good records on temperature, visibility, and spawning habits. Next, spend some time monitoring plant growth this spring. Make a gadget to collect aquatic plants from depths you can't see. It might mean taking a lead head jig, adding a big treble hook, and fishing for moss. It might be a rake with a rope tied through the handle. Be proactive with aquatic plants. If 5-10% of your pond has aquatic plant coverage—and those plants are native, non-invasive species, your pond or lake is producing habitat for baby fish.

If your water grows more than that, you have decisions to make. Will you be proactive or reactive?

Speaking of fish, catch some. Weigh and measure. Write them down. Compare this to length/weight charts available in back issues of Pond Boss or online. Plug them into a spreadsheet. Pond Boss has a spreadsheet for your perusal. Email us. We'll send it. Plug your lengths and weights into the chart and compare. You'll soon see if your fish are thriving or not.

Don't have time to collect adequate fish data? Hire a pro to survey your lake. That can be money well spent.

When a biologist enters the conversation, you'll hear the word, "balance".

Understand this: Balance is fleeting and is not likely to happen for any length of time. To help better comprehend, think of it this way... "balance" means having different size classes of the different species of fish, and all those sizes are in good body condition. That's how you can identify a semblance of balance for your pond. Remember, by design, your fishery is a "fish eat fish" world.

When the predators overeat their prey, you won't see as many size classes of those baitfish. When predators run out of food, they lose weight. Combine those two clues, and you will have to be reactive. When you see multiple size classes of baitfish and your predator fish has a size class beginning to look "average" body condition, you can be proactive by harvesting some of those predators or ramping up baitfish production via stocking or feeding a high-quality feed.

Managing an existing lake or pond means having goals to attain and regularly evaluating the pond's water, temperature, and visibility as you judge plant growth and how well your fishery is thriving. If something seems lacking, it probably is.

At that point, your mission is to dig deeper into the "Big Five" of pond management. Those are water, habitat, food chain, genetics, and a harvest plan. When one or more of those pieces of the management chain are lacking, you'll see how the fishery and related aquatic plant life respond. Whatever grows in your water is a consequence of what the water and climate offer.

Once you wrap your brain around these concepts and they make sense, and you regularly monitor or collect data, you'll better see the tasks and strategies to get your pond on track and keep it that way.

Reprinted with permission from Pond Boss Magazine