AS SEEN IN POND BOSS MAGAZINE

By Dave Beasley, Fisheries Biologist at SOLitude Lake Management 

What if I told you that there is a way to proactively manage water quality that’s not only healthy but exceptionally productive, creating an ideal environment for forage fish to thrive? What if this strategy was simple, and made it more likely to accomplish your fisheries management goals and objectives? Well, the latest science indicates that this is possible. 

The solution I am referring to supports a wide variety of lake management goals, whether you’re managing trophy bass fisheries, maximizing aquaculture production, or simply maintaining a balanced ecosystem, TryMarine offers a simpler, scalable solution. Unlike traditional nutrient-binding approaches, it empowers nature’s own processes to work more efficiently, providing a sustainable framework for long-term fishery success.

Our current strategies for managing a thriving fishery were developed over years and are a complex solution – requiring ongoing monitoring, data collection, logical analysis, and precise management. Even if done well, maximizing productivity year after year is not realistic. Often, environmental conditions limit your ability to succeed – difficult limiting factors include establishing and sustaining healthy, stress-free water quality while fostering a dense plankton bloom through the duration of the growing season.

If done well, fisheries biologists can maintain a thriving forage base while overcoming poor water quality and fish stress, but rarely is this achieved proactively. Over the years the industry has evolved, recognizing that plants and algae are not the problem, but rather a symptom of sunlight, warm water, and nutrient abundance. Although it’s technically more complicated, this awareness has led to a successful framework for biologists and managers to make better decisions. You need not control sunlight or the water temperature; as long as you carefully manage nutrient availability, you can maintain water quality, and thereby, limit the amount of vegetation and algae present.

While the mainstreaming of this nutrient-centric concept has been positive, it is far from perfect. Limiting productivity can improve water quality and suppress undesirable vegetation and algae growth, but it also restricts the capacity of the ecosystem to thrive.

When seeking to grow trophy bass or maximize biomass, restricting nutrients presents an inherent conflict with the typical primary objective of robust productivity. This challenge forces the implementation of additional strategies to redirect nutrients towards favorable species of green algae and zooplankton – managers must continually monitor and react to maintain a productive edge.

Maintaining a dense plankton bloom dominated by desirable fauna is complicated; demanding ongoing data analysis to inform decisions. Secchi, water temperature, weather, bloom color, dissolved oxygen, pH, phosphorus, nitrogen, algae ID, etc., all play a role in a well-designed, data-driven process. If you are responsible for growing fish and face the challenge of maintaining a healthy, dense bloom, you understand how difficult and risky it can be.

Bloom management has evolved to encompass a wide variety of tasks including: phosphorus, nitrogen, and micronutrient supplementation, vegetation and filamentous algae control, algaecide treatment for planktonic blue-green algae, binding of excess phosphorus, running aeration, seeding waterbodies with favorable green algae species, using low phosphorus fish feeds, monitoring of key water quality data, and even draining water bodies to remove accumulated organic matter.

So, what if excess nutrients are not the problem? Instead, the real issue lies in the natural cycle your waterbody faces. Each year, bacteria and aquatic organisms work to decompose organic matter, but this process requires oxygen. As they break down organic material in the sediment layer, they deplete oxygen. Even with aeration systems in place, delivering sufficient oxygen to deeper sediment layers remains challenging.

When oxygen runs out, beneficial microorganisms and fauna begin to decline or die off, slowing decomposition and allowing organic matter to accumulate. This triggers unfavorable changes in water chemistry, such as increased ammonia, elevated phosphorus, and a drop in pH. These conditions create a downward spiral, where poor sediment quality leads to less favorable and less diverse organisms, further limiting the ecosystem’s ability to recover. Over time, these negative conditions extend upward into the water column, diminishing the fishery’s capacity to thrive.

As water temperatures cool in the fall and winter, the slowdown in biological activity reduces oxygen demand, typically producing measurable improvements in oxygen levels, leading to improved opportunities for favorable fauna to recover. An exception to this would be for those up north during times when heavy ice and snow cover restrict the ability for photosynthesis to occur. In these circumstances, the water quality that improved in the fall runs the risk of becoming poor by late winter, prior to improving again in the spring.

Regardless of winter conditions, at some point during the next growing season, the same negative cycle of low or no oxygen in the sediments will likely revive. Unfortunately, with current management strategies, it is almost assured that more organic matter will settle in the sediments. Over time, this negative cycle inevitably impairs the abundance and diversity of favorable fauna, diminishing primary productivity.

Although it has been well-known for decades that oxygen is critical to the success of waterbodies, current mainstream solutions to improve oxygen availability are unable to overcome the combined impacts of i) excess nutrients entering the waterbody each year and ii) increasing remnant nutrients trapped in sediments. As an industry, we have developed many tools to slow the speed at which waterbodies deteriorate, but in nearly all cases, the solution comes at the expense of higher organic matter accumulation in sediments. Simply put, our industry has not yet seen a scalable solution to overcome the negative long-term deterioration in water quality.

Rather than focusing on nutrient control, a better approach—especially when managing for fish growth—is to address low oxygen levels. To accomplish this, it is necessary to maintain sufficient oxygen levels in the sediment layer throughout the available growing season, to support the natural process of aerobic bacteria and other fauna processing organics trapped in sediments. With ample oxygen, nature can constantly process nutrients up the food chain to support healthy fish growth.

As sediment oxygen demand recedes, the waterbody shifts back into a positive loop that quickly and continually decomposes organics trapped within the sediments. This accelerated decomposition process supports primary productivity goals by releasing nutrients from the muck, leaf litter, etc. into the natural resident fauna: bacteria, plankton, invertebrates and, ultimately, fish. As long as oxygen is available at acceptable levels, the transfer of nutrients up the chain and into fish promotes a more robust food chain that is anti-fragile. This approach also has a synergistic effect by addressing fish waste; an undesirable by-product is instead quickly and efficiently redistributed into the food web.

Instead of requiring the expertise of a seasoned fisheries professional to reactively develop and maintain a working ecosystem through constant nutrient and plankton management, we can now undertake a proactive approach that is significantly less complex while yielding superior productivity.

I find this lake management approach to be a refreshing alternative for those interested in fishing or fish production. It is equally attractive if you are looking to decompose organic muck to maintain healthy water quality. Decomposing organics is nature’s oldest form of lake management. TryMarine is promoting the natural method of keeping lakes balanced and continuously active in the processing of nutrients. Rather than viewing the excess nutrients as the problem, consider them a symptom of low oxygen availability within your sediments and waterbody. Rather than binding those nutrients and rendering them temporarily useless, instead, mobilize them into the food web to promote greater fish biomass.