The abundance of algae and certain other plants in our lake has been of major concern to Lake County residents for years. In his commentary Aug. 25, Jim Steele described how removal of most of the wetlands from the perimeter of the lake has allowed increased amounts of nutrients to wash into the lake from the surrounding lands during the rainy season. These nutrients enable the problem plants to flourish. The major means being used to remove the unwanted growth appears to be a filtration system that has not had any significant impact as far as I can tell. Perhaps it is time for those who are charged with dealing with this problem to consider a biological solution.
Many fish species consume a restricted diet, and they can survive only in a narrow range of water temperatures. The various members of the Tilapia genus consume algae exclusively or almost so. If a number of large pens containing numerous young Tilapia were introduced into the lake at sites where algal growth is most problematic, they might be able to consume most of the plant cells in those locations in a short period of time. The pens could then be moved to different sites for further algae cleanup.
The pens would be the same as those used by aquaculture programs that cultivate various fish species (including Tilapia) for human and animal consumption. Tilapia and other tropical species can survive only in warm water of the sort that occurs in our lake from about early summer until some time in the fall. Accordingly, before the lake temperature falls to a level that is lethal to the animals, the operators of fish processing plants could be recruited to harvest the penned fish. If any of the Tilapia escaped from the pens during the summer or fall, the cold water of the lake in winter would kill them.
An alternative method to using pens would be to release the fish into the lake when the water becomes warm enough in the spring and let them swim freely. Anglers could enjoy catching them during the summer for their own use, and when the water cools in the fall, the animals would die off. It might be possible to use different species of temperature-sensitive fish to remove the other problematic plants.
Charles S. Nicoll
Lucerne
