Management of Aquatic Weeds in Arkansas: Species and Current Control Techniques

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1 Management of Aquatic Weeds in Arkansas: Species and Current Control Techniques Patty Eklund*, Carole Engle, Mark Oliver Aquaculture/Fisheries Center University of Arkansas at Pine Bluff

2 The Natural State 600,000 acres of lakes. 3 million acres of National Forest land. World renowned trout fishing. World record brown trout, walleye, hybrid striped bass. Greers Ferry, northern AR

3 The Natural State Tourism second highest revenue producer. $5.3 billion with nearly 24 million visitors in Fishing revenue in 2007 valued at over $450 million.

4 Aquatic Plant Problems Reduce recreational use of water body. Difficult & costly to remove. Harmful to other organisms in water (toxins, oxygen depletion). Unsightly.

5 Invasive Non-native Aquatic Plants 37% of non-native introductions into Arkansas are plants (USGS 2009). Great ability to take over areas they are introduced into. Spread by recreational equipment, escape from water gardens, commercial barges, etc. Arkansas Post National Memorial

6 Agencies Managing Public Waters in Arkansas

7 Objectives 1. Identify most common aquatic weed problems in AGFC and ACE managed water bodies. 2. Identify current management techniques to control excessive growth in public waters.

8 Methods Army Corps of Engineers. Personal Interview of appropriate contact from the Arkansas ANS Task Force. Arkansas Game and Fish Commission. Survey of the AGFC District Fisheries Biologists.

9 Army Corps of Engineers ANS Task Force representative- Johnny Cantrell, Wildlife Biologist, Ouachita Project Management Office. Four Districts Vicksburg Tulsa Little Rock Memphis

10 Army Corps of Engineers Personal interview and tour of the Lake DeGray Field Office.

11 Arkansas Game and Fish Commission Survey of 10 District Fisheries Biologists

12 Questionnaire Design 44 questions. Species and locations in Arkansas. Management technique: Biological Chemical Manual Physical Mechanical Focused on public waters managed by the AGFC in 2007.

13 Survey Procedures Pre-test by AGFC Assistant Fisheries Biologist, Jeremy Risley. Assistant Chief of Fisheries requested timely response from all DFB s. Mailed in mid-january Included cover letter, postage paid return envelope. Follow up telephone call to review responses (~ 3 months after receipt).

14 Results

15 Weed Management 40% time spent on aquatic plant management. 75% invasive, 25% native Time spent has increased substantially for aquatic plant management. Time spent managing invasive aquatic plant species has increased substantially over past 5 years.

16 Species and Water bodies Main species managed: Hydrilla verticillata. Water bodies: Lakes Ouachita and DeGray.

17 Management Implemented Integrated control technique using Ctenopharyngodon idella and Hydrellia pakistanae. Raise Pak flies in nursery. First introduced in Significant decrease in hydrilla in both lakes.

18 Management Techniques Released 3.7 million Pak fly larvae between June and August in Lakes Ouachita and DeGray in Released approx. 2,000 diploid grass carp (11-12 in.) into Lake Ouachita in 2007.

19 Results

20 Time Spent Managing Weeds % Time AGFC District

21 Native vs. Non-native % Time AGFC District Native Nonnative

22 Weed Management Time spent for aquatic plant management: 40%- stayed the same 30%- increased substantially Time spent managing invasive aquatic plant species over past 5 years: 50%- stayed the same 50%- increased substantially

23 Species Managed # of Districts Coontail Am. Lotus Hydrilla So. Naiad Duckweed Yellow water lily Pennywort Alligatorweed Hyacinth Fanwort Curly pondweed

24 Management Techniques 10 # of Districts Biological Chemical Physical Mechanical Manual

25 Management Techniques # of Districts Biological Only Chemcial & Biological Chemical, Biological, & Physical

26 Biological Control Agents Ctenopharyngodon idella Agasicles hygrophila

27 Diploid Grass Carp Use Aquatic Plant # of Districts Coontail 6 So. Naiad 2 Curly pondweed 1 Duckweed 1 Filamentous algae 1

28 Diploid Grass carp Raised in AGFC hatcheries throughout state. Typically stock 8-10 inch fish. Released approx. 69,000 in 2007.

29 Alligatorweed Flea Beetles 3 years in Lake Conway Largest man-made game and fish commission lake in the US. >20% of lake covered by alligatorweed (1500 acres).

30 Lake Conway 2007 (photograph courtesy of Carl Perrin, District 10).

31 Alligatorweed Flea Beetles Do not over winter; must request each year. ~300 beetles come in Styrofoam box. Released approx beetles in Coverage <10%.

32 Chemical Control Nymphaea mexicana Hydrocotyle spp. Alternanthera philoxeroides Nelumbo lutea Eichhornia crassipes Lemna spp.

33 Herbicides Used Common Name Aquatic Plant Districts Glyphosate Yellow water lily 2 Water hyacinth 1 American Lotus 1 Pennywort 1 Duckweed 1 Imazapyr Alligatorweed 2

34 Water Level Drawdown 2 Districts. Coontail & curly pondweed. 4-5 feet for 3 months during summer. American Lotus & Yellow water lily. 3-4 feet for 5 months during winter. Neither successful.

35 Water Acreage Managed 122,950 acres in 2007 for both the AGFC and ACE managed waterbodies.

36 Conclusions- Army Corps Primary focus is on non-native aquatic weed management. Hydrilla has been greatly reduced in Lakes Ouachita and DeGray. Integrated biological control of hydrilla with grass carp and Pak flies could provide solution for new areas infested with hydrilla.

37 Conclusions- Game & Fish Half of the DFB s are spending 90% or more of their efforts on native species. All Districts that are managing aquatic weeds are using some form of biological control.

38 Game & Fish, cont d. Most frequent non-native aquatic weed problems in public waters throughout all districts are hydrilla and alligatorweed. Increased interest in using biological control agents for management.

39 Acknowledgments Johnny Cantrell, ACE and Jeremy Risley, AGFC. AGFC and AGFC District Fisheries Biologists. University of Arkansas at Pine Bluff, Aquaculture and Fisheries Center

40 QUESTIONS?