Transition Water – Why is Fish Fry Lake So Productive?

Why is Fish Fry Lake so Productive?

Let’s clear up a misconception here. Some folks believe that eutrophic or hyper-eutrophic lakes are productive. This is not so. They have excess nutrients, but the nutrients invariably short circuit. They have nowhere to go, nothing to fertilize. They stack up, accumulating in the water column… then such lakes run out of dissolved oxygen. As they slip into anoxic and/or anaerobic status, and their actual productivity diminishes by more than 80%.

In a waterway managed for health, these ubiquitous excess nutrients are cycled through the food web and out of the water. Ideally this is in the form of preferred biota, like game fish. But the form is less important than the fact that some of these nutrients are cycling up and through the food web somewhere…and eventually, out of the waterway, through some kind of harvest. When more nutrients are cycling out of a waterway then are coming in, the waterway is in Transition, and moving up on the trophic ladder. This can be accomplished by design. We call this process Transition Water.

Dissolved oxygen, sunlight, surface area and circulation are the four primary variables that can enhance or limit a waterway’s productivity. For example, turbidity limits sunlight. Many folks believe they can get around this by feeding their fish, instead of relying on their waterway’s natural food web. Fish feed is a form of added nutrient. Even if the fish eat it all, they still excrete nutrient-rich guano that has been added to the system. These organic-bound nutrients are easier for your waterway to process, admittedly, but introduced food still contributes to a waterway’s downward spiral which is directly connected with excess nutrient load. And beyond this, the omnipresent inflow nutrients in such a setting are probably stacking up too. This is a formula for an eventual fish kill. The waterway is in a downward spiral.

Take any one of these four key factors and improve it, (dissolved oxygen, sunlight penetration, surface area, circulation) and your waterway’s health will improve. So will its productivity. Do all four – then add the vital element of strategic harvest, and you will have a Transition Waterway.

Harvest. If you can cycle more nutrients out of your water than are coming in, water quality will improve. This is manifested by the usual characteristics of quality water, such as water clarity, bio-complexity, health of resident biota, growth rates, and of course, absence of toxins in your water.

We do all four at Fish Fry Lake, albeit in fits and starts some of the time. We also harvest at levels that compare with inflow nutrient load. Here are some of the results:

Dissolved oxygen does not drop precipitously now, as it did before. Our floating stream beds contribute to this, as does enhanced diatom presence.

Today sunlight extends deep into the waterway, triggering diatom growth, and a more steady-state dissolved oxygen condition has developed.

Bio-complexity continues to expand, with life forms like native fresh water sponge colonizing the underside of floating islands, and wild flowers like Indian Paintbrush occurring on top. Both add surface area and, in the case of fresh water sponge, filtration, which contributes to improved water clarity.

Circulation within Fish Fry Lake is associated with inflow/outflow of from 65 to 80 gallons per minute, wind and wave action, and the mechanical action of two floating stream beds. This combination results in suspended solids and colloidals being filtered onto biofilm present on the stems and leaves of aquatic vegetation, the perimeter of rock and cobble and deadheads designed into the lake’s benthic zone, and the surface area associated with roots growing through over twenty islands present on the lake, as well as onto the saturated filter matrix material that islands are composed of.

Harvest also takes numerous forms. For example, we annually harvest from six to eight thousand fish from specific age classes from the lake. We also harvest other biota, like the invasive American Bullfrog, and aquatic vegetation. The fish are cycled out of the lake, and/or into bigger class fish within the lake, which in turn are harvested for human food. The bullfrogs are harvested for human consumption, and the aquatic vegetation is cycled into worms and worm castings. Some of the worms are cycled back into fish, but most are retained and generate valuable worm castings which are cycled into our property.

Doing all of this on a planned basis, instead of happenstance, is challenging. But the “theme” is valid. Even if you can’t afford to “quantify” your actions, when you do improve all five of these variables, your waterway gains new life. See our Lake & Pond Management section for more information.