Effects of Vegetation on Fish Populations

Excessive pond vegetation can not only make boating or fishing difficult, but it can also have serious impacts on the largemouth bass population. We like to see ponds with 20% or less vegetation coverage. When the vegetation gets above 20% coverage, that’s when we usually start seeing impacts on the fish populations.

Vegetation does indeed make great cover and habitat for prey species like bluegill and redear sunfish. But if these prey species have too much cover, predators like largemouth bass will have a tough time capturing those prey species. The end result is that the bass expend too much energy trying to capture their sunfish prey. Because they’re expending too much energy finding prey, their weight is not what it should be and the bass population is generally in poor health.


Spraying Surface Pond Vegetation

What Makes Pond Vegetation Thrive?

We find that the two most common causes of excessive pond vegetation are water clarity and shallow banks. If the pond water is too clear, light can easily penetrate much deeper into the water column. This usually results in an abundance of subsurface vegetation in the pond.

This issue can usually be solved pretty easily by improving the pond fertility. A fertile pond will not have super clear water and thus the light can’t penetrate that deeply into the water. Liming and fertilizing to improve the plankton population abundance will often reduce any subsurface vegetation issues.

If the banks around a pond are too shallow, you’ll often find that pads and other surface weeds tend to congregate there. If those banks are made steeper, light won’t be able to penetrate to the bottom of the pond along the banks. As a result, surface vegetation will tend to be less in those areas.


Pond Vegetation Spraying Rig

Approaches to Pond Vegetation Control

There are several different methods that are frequently used to try to reduce excessive vegetation in a pond. One of those is mechanical removal, which we haven’t found to be that effective. Mechanical removal sometimes works for surface weeds, but it’s quite ineffective on subsurface weeds that have rhizomes in the pond substrate. Yes, the mechanical removal may make the pond look clean for a few weeks, but the subsurface vegetation usually grows back with a vengeance.

The best way to regain control of an overgrown pond is through chemical removal or spraying. Our pond spraying rig allows us to treat surface vegetation with a spray wand and also treat subsurface vegetation with underwater nozzles. If you have a significant amount of subsurface vegetation in a pond, you’ll need to make sure you’re using underwater nozzles to effectively treat it.

You do have to be careful not to spray too much of a pond at one time. When removing a significant amount of vegetation from a pond, you’re also removing a significant amount of oxygen that is being produced by those aquatic plants. As such, we like to spray larger ponds in two week or monthly intervals so that we’re not stressing the fish populations too much. We’ll spray a couple acres at the time until the entire pond has been treated.

Once we’re able to regain control of the pond vegetation through chemical controls, we can then begin to use more biological controls to manage the pond vegetation over the long term. As mentioned above, one of these biological controls is improving water fertility so that water clarity is reduced. This reduces light penetration into the water column and helps prevent subsurface vegetation from becoming a problem again.

Another important biological control would be the use of vegetation consuming species like grass carp. It is important to note that there are some caveats with this solution. Grass carp won’t eat everything. So you need to make sure they will eat your problematic vegetation before stocking them. Also, these fish tend to become quite lazy when they get large and old. So it’s likely that you may have to restock at some point.


Contact Us for More Information

If you’re a pond owner, it’s important to keep a close eye on your pond vegetation. It’s a lot easier to control if the problem is minimal. But if you let the pond become overgrown with weeds, it can be quite the struggle sometimes to get it back to being a quality fishery.

If you’d like to see our pond spraying rig in action and learn more about pond vegetation control, click the link below to see this blog in video format. Be sure to SUBSCRIBE to our YouTube channel to receive updates every time we post a new video. If you are in the south Georgia or North Florida area and could benefit from our pond management services, COMPLETE THIS FORM and we’ll be glad to help.