Workshop Field Trips

Workshop participants visited two lakes with different densities of quagga mussels and received information on ways to detect mussels at low densities and methods for eradicating and controlling mussels.

Lake Murray (low mussel infestation)

The mussel infestation at this lake remains low. Jonathon Thompson and Steve Chilton, USFWS, led participants in an early detection survey of mussel-infested boat bottoms. To test participants’ abilities to detect mussels, a contest was held for finding the smallest mussel.

Participants also learned about using visual and tactile methods of detection, along with deployment and monitoring of artificial substrates through demonstrations and discussions with Dr. Carolynn Culver and Heather Lahr, California Sea Grant Extension Program.

El Capitan (high mussel infestation)

The mussel infestation at this lake has reached extremely high levels. Participants were able to see very high densities of mussels on vegetation and rocks that were exposed due to a drop in the water level. Dr. Culver led participants in visual and tactile surveys on the docks as well as artificial substrates, providing a comparison of a high and low (Lake Murray) mussel density situation.

Participants also learned about various eradication/control methods, including:


Dr. Lars Anderson, USDA-Agricultural Research Service, and Dan Daft, City of San Diego, illustrated how to implement tarping as an eradication/control strategy. This strategy was successfully used for eradication of Caulerpa taxifolia in Southern California in 2006. (download pdf)

Removal by Hand

Dr. Sandra Nierzwicki-Bauer, Rensselaer Polytechnic Institute and Darrin Fresh Water Institute, with assistance from Heather Lahr, California Sea Grant Extension Program, illustrated methods for removing mussels by hand from various substrates (rocks, vegetation). The use of different tools and tips for containing the mussels as they were removed were discussed. A contest for removing the most mussels was held.

Dr. Nierzwicki-Bauer used this method to eradicate zebra mussels from a lake in New York (link to her paper). Dr. Culver also has successfully used this method for eradicating a marine aquatic pest. 

Mechanical Removal

Heather Lahr also illustrated the use of a simple airlift vacuum for collecting mussels as they are scraped from a substrate. This vacuum runs off a SCUBA tank and accommodates sample bags of different sizes. Dr. Culver has used this underwater system for collecting marine invertebrates.