MAYFLOWER – Fertilizer will be applied to Harris Brake, Overcup and Cargile lakes from May4-8. AGFC fisheries biologists attempt to apply fertilizer to these three lakes on an annual basis. The fertilizer will be applied to the lakes by airplane.
Biologists plan to apply a granular fertilizer that is high in phosphate (18-46-0), which helps boost the production of phytoplankton. Phytoplankton is a microscopic plant that is the foundation of the food web in aquatic systems. It is what gives most ponds and lakes the green color during the spring and early summer months.
It is a common management practice used on lakes across the state, according to AGFC District 10 Lake Manager Matt Horton. "We typically apply fertilizer to lakes in the spring, starting in April or May, when the water temperatures climb above 60 degrees. If fertilizer is applied too early in the year it promotes the growth of nuisance algae before phytoplankton has a chance to bloom," he said. "Adding nutrients to the water enhances the phytoplankton bloom and results in decreased water clarity. This hinders the growth of nuisance algae and aquatic plants. It also increases the production of microscopic organisms called zooplankton, which larval fish (fish that just hatched), such as bass and crappie, need to feed on to increase their growth during their early life stages," Horton explained. "The latter is the most important goal of applying fertilizer to the lakes. Fertilization increases the overall productivity of the water body by stimulating the food web, which eventually produces more food for sport fish such as largemouth bass, crappie, catfish and sunfish," he added.
Horton said occasionally, fisheries biologists receive complaints from anglers that their catch rates drastically decrease for a week or two following the application of fertilizer to a lake. "Anglers have reported this phenomenon for decades, but we have not found any water quality variables, attributed to the fertilizer, which would cause such a drastic change in fish behavior," he said. Instead, biologists suggest that numerous natural environmental variables, such as water temperature, water turbidity, cloud cover, wind speed and water level fluctuations may be to blame. "Any or all of these natural conditions can have negative and positive impacts on fish behavior and feeding patterns," Horton added.
Horton conducted a study on Lake Overcup in 2010 to investigate angler's claims that the application of fertilizer to a lake negatively effects fishing for a short period of time. His research report can be found on the AGFC website under "Fisheries Research Reports" at: http://www.agfc.com/resources/Pages/ResourcesScientificReports.aspx
. The report is titled "Effects of Lake Fertilization on Bluegill Catch Rates."
For questions about this management practice, contact the District 10 fisheries biologists at the AGFC Field Office in Mayflower by calling 877-470-3309.