Game and Fish works to improve fishing conditions in Arizona lakes

Jan 4, 2006

Game and Fish uses an aquatic weed cutter to clear plants and weeds from a lake.

PHOENIX -  We all know that removing weeds in our backyards and gardens can help other plants thrive, but can removing aquatic weeds from Arizona's lakes help to improve fish growth and fishing conditions? That's what the Arizona Game and Fish Department is trying to figure out.

"Aquatic plants play a major role in lakes and ponds," says Jimmy Fulmer, an Arizona Game and Fish Department researcher, "but too many plants can keep larger fish from thriving in a given lake and can even cause fish kills."

That's why the Arizona Game and Fish Department is conducting a lake management study and using an ongoing weed harvesting program at Arizona lakes. Study surveys have already been carried out in locations across the state, including the Flagstaff area's Lower Lake Mary, Stoneman Lake and Marshall Lake; the Phoenix area's Lake Pleasant and Apache Lake; the Prescott area's Granite Basin and Willow Creek; and southern Arizona's Arivaca, Patagonia, Parker Canyon and Pena Blanca lakes.

"The surveys involve looking at the kinds, distribution and abundance of aquatic plants in bodies of water," says Fulmer. "Then, we get an accurate list of the plants and can better create guidelines to manage the lakes."

Researchers survey the lakes by taking a 10-foot extendable rake, dropping it to the bottom, and turning it 360 degrees before pulling it back into the boat. The aquatic plants are then identified or taken to a lab for further analysis. Samples are taken at 100 points at each lake, using the help of global positioning system (GPS) technology to navigate to specific points for a variety of samples. Twenty-three more lakes will be surveyed as part of the department's aquatic weed study this year.

Parker Canyon and Pena Blanca lakes are among those that have already gone through actual weed harvests during the department's 25-year-old weed harvesting program. These harvests involve the use of a huge aquatic weed cutter that looks like a piece of construction equipment. The department harvests and removes literally tons of weeds from key lakes every year. In fact, last year 2,750 tons of weeds were removed from Arizona lakes and ponds.

Researchers are examining water quality both before and after some of the weed harvests, in order to help determine whether the harvests really benefit sport fish and anglers. The researchers look at key nutrients that are expected to change with the removal of aquatic plants.

The ultimate goals of both the weed harvesting program and the study are to provide Arizona anglers with better fishing access and better fishing conditions at lakes, including larger fish and more fish. The research should help determine how effective the department's weed harvesting program is, and hopefully, also help determine good alternative ways to create better lake habitat for fish and fishing. Results of the study will be available after it's complete in the summer of 2007.

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