Fish Kill: Thinking in the Deeper Water

Fish Kill: Thinking in the Deeper Water

By Bob Lusk

At the end of October last year, I got a text from a young ranch manager in the plains. I read the urgency in his words. “ Do you have time for a quick call? We’ve had a massive fish kill after a pond management company was here spraying weeds.”

He manages a nice-sized prairie cattle ranch for a well-to-do family from a large metropolitan area. Near the headquarters sits a three to four acre spring-fed pond that collects crystal clear water from surrounding sands. I’ve known this young man for years, so I rang his number immediately. We talked and he explained what had happened, along with a fairly detailed stocking and management history that tracked back before his employ.

Seems the family, shortly after buying this ranch as an investment, found a pond company online. This was four or five years ago. The company proprietor is a savvy young guy, with marketing skills and a degree in fisheries along with a handful of years’ experience. Over several years, his company sold quite a few thousands of dollars of fish and related products to this particular client.

All the family wanted was a weekend retreat where the kids could catch some nice fish when they were there and have a fish fry for the family from time to time. The pond company set up feeders, made sure the customer had plenty of feed and encouraged them to buy more fish each year to supplement what they already had. He sold them some fertilizer each year and then more fish and more fish food. With those fish, doses of fertilizer, and feed came some simple instructions. “ If the water is too clear, fertilize it. If the fish don’t eat all the feed in ten minutes, cut back.” The basic stuff one would expect.

Over four or five years, during a drought, the spring was able to keep up with evaporation some of the time. But, the pond dropped each summer, and would catch up during winter, when evaporation was less. This is a clue, folks. The fishery matured with chunky feed-trained largemouth bass, big bluegills, meaty redear sunfish and hybrid striped bass. The water was gin-clear and the pond bottom was gritty and sandy. It was paradise.

This is another clue.

Does this story sound like anyone you might know in your neighborhood? I see this scenario happen over and over.

That customer wrote lots of nice checks over several years, bought lots of stuff and the pond company made good money. Good money. Then, without good knowledge beyond selling fish, and apparently without enough experience, that good, expensive fishery was flown into the ground because of one stupid incident. Heavy on the word stupid.

All the landowner wanted was for his kids to catch some fish and have fun with a sustainable pond. A significant investment in fish, food, time, and stuff was lost because a professional pond management company didn’t have the foresight, the knowledge, or the experience to think about the impact on the water and the fishery when they added $80 worth of an approved herbicide. After all, the herbicide was labeled for that use.

Another clue.

So, how much would it have been worth to that customer to have asked a few questions or gotten a second opinion BEFORE all those nice fish were killed because of someone’s lack of knowledge and experience? And, the saddest part is that the vendor probably had a little meeting afterward with his young, inexperienced staff, scolded them a little bit, and didn’t really know what to tell them to prevent that same occurrence from happening to someone else. Here’s what they didn’t know: That water in the middle of those plains, in that watershed, has several qualities that expedites the efficacy of certain chemicals and causes them to bind with minerals and metals dissolved in that water, which can cause rapid degradation of certain types of plants. After all, why would they know that? They sell fish and kill plants. They’ve never had the forethought to figure out these different watersheds and their limiting factors. That’s what happens when someone sells fish and stuff.

Trust me, I’ve made similar mistakes. Over a beer at Pond Boss VI Conference and Expo, call me aside and ask for some stories about dead fish. I’ll share…especially if you’re buying the beer.

My daddy used to say, “ It’s not what you know that kills you, it’s what you don’t know.” Boy, was he right.

Go a little deeper under the water of that plains-area pond—spring-fed, evaporation, feeding fish, and fertilizer—BIG CLUE. Mix those things together and here’s what you get. Fresh water coming in, but not flowing out. Evaporation caused water losses. What’s the big deal about that? When that water percolates through soils, it’s dissolving everything it can. In that watershed, there’s gypsum, limestone and all kinds of organic matter, especially grasses that contacts runoff as it percolates down and laterally into that ancient draw where this pond sits. So, there’s an input of metals and minerals from the water source. Add the nutrient load from the fish food and fertilizer, and it doesn’t take long for a buildup. As the water evaporates from that piece of paradise, the only thing that leaves the pond is the water. Everything else stays behind. Over time, all that dissolved stuff which isn’t water accumulates and nature does all it can to convert it to something else to get rid of it. Some stuff decomposes and turns to gas, which releases into the atmosphere. Other stuff flocculates and binds into the bottom soils. But, heavy on the word but,lots of those minerals and micronutrients turn into greenery.

Another clue? Gin Clear.

If a pond with minimal flushing, stocked with fish every year and those precious creatures are fed faithfully, how can the water be clear?

I’m asking you, dear pondmeister?

Good answer! The pond is filling with rooted macrophytes. Plants, greenery, underwater salad. Bushy pondweed, coontail in the water, cattails thriving in shallow shoreline areas. Plants caused the water to be clear, rather than having a plankton or blue-green algae bloom. Plants, plus massive amounts of dissolved minerals and metals kept the water clear.

The other clue? Approved herbicide. Why is that a clue? Complacency. If a young biologist can read and interpret a label and has an ounce of sense about how to measure volume of water in a pond, then figuring out how much herbicide to dose is simple. If they can identify the plant, get some idea of the coverage, the treatment should be fairly simple. Do the math, make sure you’re using the right stuff for the proper plant, measure, spray, get a check and go home. Job done.

No, it isn’t. The seasoned pros have the scars of experience to tell you that it’s not that dang simple. If it was, the whole pond management industry would be full of folks identifying plants in some book, squirting some chemical on it and calling it good.

Those whose seats have been burned know much, much more comes into play, especially as a pond ages. Those pros can see the proverbial gray hairs beginning to show up in the pond. They know to exercise caution when it comes to eradicating plants in mature waters.

This pond management company should have known it, too.

So, what’s the lesson? What are your take home points?

First, pay attention to a pond as it matures. Those plants didn’t grow in one year. They represented four or five years of growth. Do something in year two or three. Not five. Second, study that water. Do regular sampling and compare over time. If you see a buildup of certain minerals, metals or nutrients, ask for interpretation. Third, don’t be afraid to call something into question. Just because a label says its good doesn’t mean you shouldn’t have a strategy. I’m a believer in using herbicides as a best management practice when they are the best choice, or even one spoke of the entire protocol wheel. But, why kill all the plants at one time, especially in the month before they go dormant anyway? Not smart.

The biggest lesson? Think beyond the obvious. Realize it’s more than, “ Water come. Water go. Stock fish. Feed fish. Plants grow. Spray plants. Plants die. All good.”

Nope, not quite.

How’d it end for the ranch? They made the call and the pond company owned their mistake. Good for them. Shows they have some ethics. I’ll give them a round of applause. They replaced some fish. But, they couldn’t replace those five years or the growth of those fish in which the landowner had invested.

Your mission from this story? See beyond the obvious, stay proactive, ask questions and understand the depth of your pond’s life.