Background:
Aquatic plants are an integral part of aquatic ecosystems because they have a major influence on oxygen balance in aquatic systems, play key roles in nutrient cycling, light penetration, and water temperature stability, reduce erosion of stream and riverbanks, lake and reservoir beds, and shorelines, and fish, waterfowl, insects, mammals and microscopic animals use aquatic plants for food, shelter, and habitat. However, excessive densities and biomass can be considered problematic because recreational activities such as swimming, fishing, and boating can be impaired or prevented. Excessive densities and biomass can also result in stunted fish growth and overpopulation of small-bodied fishes. In addition, nonnative invasive aquatic plants can invade and take over stands of native vegetation.

Arizona Game and Fish Department has used multiple techniques to manage nuisance aquatic plants, including stocking triploid grass carp, treating ponds or lakes with aquatic herbicides, and using aquatic weed harvesters to cut and remove plants from the water. The current study was initiated for two reasons:

1) Excessive coverage of aquatic plants can obstruct angler and recreational user access, and can negatively impact water quality, which can result in fish kills, declines in fish production, and cancellation of fish stocking; and 2) Arizona Game and Fish Department does not have an aquatic plant management strategy or an accurate inventory of aquatic plant species in Arizona's water bodies. Objectives addressed in this study are: 1) determine distribution and abundance of aquatic plant nuisance species in Arizona sport fishing waters; 2) evaluate if Arizona Game and Fish Department's aquatic weed harvesting program is benefiting sport fish and fishing access; and 3) develop aquatic weed management guidelines and protocols for Arizona Game and Fish Department.

Location:
Our weed harvesting program will be evaluated on lakes in the White Mountains area and in southern Arizona. Aquatic vegetation will be surveyed in lakes and ponds throughout Arizona.

Approach:
Evaluation of AZGFD Aquatic Weed Harvesting Program. Water chemistry and vegetation coverage will be monitored before and after harvesting of aquatic vegetation in targeted lakes (4 in 2005 and 4 in 2006). Angler survey stations with survey cards will be installed at targeted lakes in 2006 and an internet survey will be done to determine angler and public attitudes towards aquatic plants and aquatic plant management. In addition, costs and benefits of the current program will be assessed.

Statewide Aquatic Vegetation Survey. A minimum of one lake or pond (randomly selected, but targeting those with boat ramps where possible) on each of the 41 watersheds on non-tribal lands will be surveyed to determine aquatic species composition and abundance. All lakes where aquatic plants have been harvested in the past will be surveyed. Transects will be established in each lake, and at 100 points along those transects, aquatic plants will be sampled with a rake, and identified.

Aquatic Plant Management Guidelines. States and select federal agencies will be surveyed to identify their aquatic plant management programs and guidelines. In addition, an intensive literature review of aquatic plant management, and invasive aquatic plant species will be conducted. Data from our statewide aquatic plant surveys (objective 1) will be used to identify aquatic plant species and their distributions. Information will be compiled and guidelines for aquatic plant management in Arizona will be written. Guidelines will outline an integrated approach using mechanical, biological and chemical control methods.

The study will end and a final report will be completed on June 30, 2007.

The Department's aquatic weed harvesting program will benefit by an evaluation of the program that includes recommendations for improvement. Regional fisheries managers, and state and federal agencies (e.g., Arizona Department of Environmental Quality, U.S. Forest Service, U.S. Bureau of Land Management) will benefit by having guidelines to manage aquatic plants in Arizona and an inventory of the common aquatic plants on their lands. The information generated during this study will identify waters where invasive aquatic plant species occur and suggest strategies for addressing highest priority problems.

For more information contact:
Anthony Robinson, Arizona Game and Fish Department, 5000 W. Carefree Highway Phoenix, AZ 85086-5000 .
Phone: (623) 236-7376 E-mail: trobinson@azgfd.gov