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Recreational Boater Movement in California and Nevada and Implications for Dreissenid Mussel Introduction to
Inland Water Bodies
October 21‐22, 2010Sacramento, CA
Marion Wittmann, [email protected]
Acknowledgements
• University of California Center for Water Resources (Funder)
• US Fish and Wildlife Service Western Regional Panel (Funder)
• Tahoe Resource Conservation District and Tahoe Regional Planning Agency (Data)
• University of California Davis and University of Nevada Reno (Support)
“…bombardment of every country by foreign species, brought accidentally or on purpose, by vessel and by air and also overland from that used to be isolated…”
‐Elton 1958
Long distance dispersal events greatly increase the speed of invasions, the expansion of ranges
Skellam 1951, Hengeveld 1989, Shigesada et al. 1995
Sharov and Liebhold 1998
Known Dispersal Vectors
• Boats (recreational, commercial)
• Fishing equipment (creels, boots, lures)
• Waterway connections (rivers, canals, currents)
• Waterfowl
• Aquarium or ornamental release
StateState Area
(sq. mi.)
Number of Registered Boats 1
(2005 Ranking)
Statewide Population
Boats per
capita
Approximate number of boat‐able
inland water bodies 2
Boat Ramps
Boat ramp per registered boat
Number of boat able
water bodies per registered
boat
Florida 65,758 973,859 (1) 18,089,888 19 7,700 535 0.0005 0.0079
California 163,707 963,758 (2) 36,457,549 38 404 355 0.0004 0.0004
Michigan 96,810 944,138 (3) 10,095,643 11 11,000 1302 0.0014 0.0117
Minnesota 86,943 853,489 (4) 5,167,101 6 5,400 3031 0.0036 0.0063
Wisconsin 65,503 639,198 (5) 5,556,506 9 15,000 2000 0.0031 0.0235
Nevada 110,567 57,726 (40) 2,495,529 43 200 41 0.0007 0.0035
[1] National Marine Manufacturer’s Association. 2005. U.S. Recreational Boat Registration Statistics. [2] Boat U.S. 2007. Boat Owner’s Association of the United States “Places to Boat and Fish”. [3] California Department of Boating and Waterways Boating Facilities and Needs Assessment 2002. [4] Boat U.S. Boat launch ramp locator. [5] Michigan Department of Natural Resources, Lake Access Point List, 2008. [6] Minnesota Department of Natural Resources, Lake Access Point List, 2008.[7] Boat U.S. Boat launch ramp locator[8] Wisconsin Department of Natural Resources, Boat Ramp List 2008.
U. S. Spatial boating statistics: Top Five Boating States……And Nevada!
Wisconsin boaters
Buchan and Padilla 1999
Ontario Boaters
MacIssac et al. 2004
International Shipping Traffic
Drake and Lodge 2004
Watercraft and boater travel as observed in other systems
Distance travelled (km)
Frequency histogram of distances travelled by boaters travelling to top used Nevadan and Californian inland
waterways (N = 778)
Distance (m x 105)
County Origins of Tahoe Survey County Origins of 100th Meridian Survey
Two Surveys:‐Collected at Lake Tahoe, N = 778‐Collected by the U.S. Fish and Wildlife Service 100th Meridian Initiative, N = 1312
A gravity model is a transportation model that is used to estimate the volume of traffic moving between
places: It is based on distance and the attractiveness of a destination
ij
K
ijiij dWOAU
1
Thomas and Huggett, 1980
MacIssac et al. 2004, Ecological Applications
Linking Spiny Waterflea (Bythotrephes longimanus) invasion with Gravity Models
+
So, how does the estimation of distance impact the gravity model?
ij
K
ijiij dWOAU
1
In the midwest, use a power distribution
Because of the western landscape we have to think about this differently
Bimodal, R2 = 0.91, p < 0.01Power, R2 = 0.53, p < 0.01
Tij (Bimodal)
T ij(Po
wer)
Depending on how you incorporate distance into the model, the prediction of risk changes
We have to not only think about lakes that are close to us, but lakes that are farther away too!
Boater attraction: What motivates a boater to drive hundreds of kilometers!?
ij
K
ijiij dWOAU
1
Distance Surface Area of waterway
Ramp lanes
Fishing tackle for sale
Parking Spaces
SecchiDepth
Convenience store
Sportfishery
Boat wash facilities
Sacramento (N = 208)
x x x x x
Roseville(N = 55)
x x x x x
Elk Grove (N= 79)
x x x X x
South Lake Tahoe(N = 103)
x x x
Reno, NV(N = 153)
x x x x
Carson City, NV (N = 127)
x x
Las Vegas, NV (N=99)
x x x x x x
Using Logistic Regression, the probability of site selection as explained by waterway attributes. Waterway attribute data compiled by the California Department of Boating and Waterways
No sites with Dreissenid mussels!!
3 of 4 top used sites in Nevada have Dreissenid mussel presence
2009 State originations of Lake Tahoe Recreational Boaters, N = 13,748Boat Launch Inspection Survey Data, 2009
Conclusions• Be careful how you analyze your data• Boater databases can help to estimate high probability
connectivity between waterways but may not include low probability, long distance dispersers—These events drive invasion speeds‐‐With some species, it just takes one!
• Recreational boaters are willing to travel for a variety of reasons to use waterways including distance, amenities and resource quality
• A precautionary approach toward invasive species management and prevention provides the highest probability of delaying or avoiding an introduction of an unwanted AIS
Thank you very much for your attention!
Questions?
Number of trailered boat launches in Lake Tahoe in 2009, N = 19,148Data collected by Tahoe Resource Conservation District, Tahoe
Regional Planning Agency
State originations of trailered recreational boats launching atLake Tahoe in 2009, N = 13,748
Lake Tahoe Boat Launch Inspection Survey Dataset (TRCD, TRPA)