Results of Zebra Mussel Surveys Lake Mead National Recreation Area Dr. Shawn Gerstenberger University of Nevada Las Vegas Department of Environmental Studies January 17, 2003

Four Main Survey Types 1) Trailer Counts for Launch Areas*** 2) Trailered Boat Survey (interview) 3) Boater Self Survey (windshield) 4) Boat Traffic Summary* All surveys are approved by the committee on the use of human subjects at UNLV.

Survey Dates (26 trips so far) October: 19 and 20 November: 1, 7, 22, 23, and 24 December: 1,5,6,7,8,14,16,17,26,27,28, and 29 January: 3, 5,6,7,8,14, and 16

Location of Sample Sites Lake Mead National Recreation Area Overton Beach Echo Bay Callville Bay Las Vegas Bay Lake Mead Marina Hemenway Harbor Willow Beach Katherines Landing Princess Cove Cottonwood Cove

Trailer Count for Launch Areas and Related Facilities Survey Totals Start Date: October 19, 2002 End Date: January 8, 2003 Total Trailers Surveyed: 1871

Totals By State Other States Include: Texas, South Dakota, Montana, Kansas, Mississippi, Washington, Minnesota, Arkansas, Missouri, Florida, Illinois, Kentucky, Louisiana, New Mexico, New York,Pennsylvania

In State vs. Out-of-State Nevada –Total: 1221 –63% Other States –Total: 650 –37%

Summary of Observations Nothing Found Grass pieces found on trailers from Kansas, no organisms present.

Totals By Month October –Total 685 NV 376 Other 309 November –Total 472 NV 307 Other 165 December –Total 657 NV 462 Other 165 January –Total 118 NV 82 Other 36

Future Surveys Awaiting Park Service approval for Interviews and Self Surveys 1000 self-surveys (Self-Inspection Forms) with pre-paid postage are copied and ready to be placed on windshields. A few Trailer Boat Traffic Survey forms have been completed (data not shown).

Future Surveys (cont.) Will continue to sample through warm weather months. Interviews and mail in surveys will be completed ASAP.

Summary Trailers originating from 26 different states have been documented. Predominantly from Nevada and adjacent states, but states East of 100 th Meridian are present. No visible signs of ZM or other potentially invasive species noted on trailers.

ACKNOWLEDGEMENTS US FISH AND WILDLIFE SERVICE LAKE MEAD NRA CAROL LANE MEGAN MCCOY