Largemouth Bass & Hydrilla

Aquatic plant management is paramount. Controlling weed growth in a lake is really important. Having too many of these green suckers is bad; and not having enough ain't great either. But before you think I'm starting to get all hippie on you, talking about how it's important to save some crazy, unknown species of endangered frog, let me say that controlling weed growth is not just a matter of ecology -- it's also about money (somewhere Kevin O'Leary is smiling).

For example: "Economic analysis of the fishery at Lake Guntersville, Alabama, projected that the greatest positive impact on the local economy from recreation would be achieved at 20% plant coverage.  This amount of coverage allowed the highest levels of angling and nonangling recreation without being hindered by excessive plant growth" [1].  In other words, if you can find a level of weed growth that pleases fishermen, boaters, swimmers, and anyone else interested in going on the lake, you can maximize tourist revenue.  But what happens to the bass when you remove vegetation from a lake?

A frog in hydrilla 

One study on Lake Seminole attempted to determine changes in movement and behavior of largemouth bass before and after hydrilla reduction. The following observations were made:

• Movement, especially during the day, increased
• Largemouth inhabited greater depths, again, particularly during the day
• Home range did not change (in other words, fish generally stayed in the same area)
• As hydrilla was reduced, largemouth switched from using primarily hydrilla as cover to large woody debris, mostly stumps

Photo by Nicholas Kalimin (he also caught the fish!)

For fishermen, the obvious lesson from this research is to look for stumps where there has been a reduction in hydrilla, and, potentially, to fish a bit deeper. The other thing to keep in mind is that with fewer weeds, fish are more likely to forage rather than ambush. So faster presentations, like crankbaits and swim jigs, might be more effective than they otherwise would be. And don't forget to bang those lures off them stumps! If you do, you just might catch a few more fish.

Remember, knowledge is important, but it's no substitute for experience!

[1] Henderson, J. E. 1996. Management of nonnative aquatic vegetation in large impoundments: Balancing preferences and economic values of angling and nonangling groups. Multidimensional approaches to reservoir fisheries management. Am. Fish. Soc. Symp. 16:373-381.

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