AIS Inspectors Encounter Unusual Situation At Wibaux

Helena - Watercraft inspectors at the Wibaux inspection station intercepted a motorboat entering Montana with mussels attached. The Wibaux inspection station, located on the Montana-North Dakota border on Interstate 94, has intercepted 12 of the 54 mussels boats intercepted so far this year. This boat was unique in how the mussels were attached to the boat.

Invasive mussels have byssal threads they use to attach to underwater surfaces. The threads or “hairs” are an adaptation found on invasive zebra and quagga mussels but are not found on North America’s native freshwater mussel species. Invasive mussels can move from one water body to another when their threads attach to the hull or motors of trailered watercraft or when microscopic mussel larvae floats in standing water inside vessels.

The motorboat that Wibaux inspectors encountered on Sept. 6 had just pulled out of Lake Lida in Minnesota that morning after two days on the water. A close check by inspectors found tiny mussels that were hydrostatically clinging to the motor, transom and hull rather than attached with byssal threads.

The hydrostatic process allows water molecules to bond surfaces together, in this case mussels and the motorboat, and maintain that bond after the water has dried. It’s presumed that invasive mussels were floating near the Lake Lida boat ramp and were able to cling to the boat as it was loaded onto the trailer.

“It’s alarming that this boat had mussels attached after only two days in the water,” said Zach Crete, AIS Prevention coordinator for FWP. “Normally, a boat would have to be moored in the water for several days before mussels would have time to attach.”

Inspectors performed a viability test on several mussels and found some were still alive and siphoning water.

FWP staff reminds anyone transporting motorized or nonmotorized boats into Montana that an inspection is required before launching, and stopping at ALL open watercraft inspection stations is required. Failing to stop at an inspection station can result in a fine of up to $500.

Boaters should ensure their watercraft, trailer and all equipment that is in contact with water (anchor, lines, swim ladder, etc.) is clean, drained of water and dry.

Learn more at or call the FWP Aquatic Invasive Species Bureau at 406-444-2440.


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