Zebra mussels have been confirmed in Fish Trap Lake near the city of Motley in Morrison County, according to the Minnesota Department of Natural Resources. Fish Trap Lake will be designated as zebra mussel infested.
On June 30, a lake user reported a zebra mussel attached to a submerged tree branch near shore in Fish Trap Lake that was later confirmed by a DNR aquatic invasive species (AIS) specialist. DNR staff surveyed the lake Thursday and found an established population of adult zebra mussels in widespread areas of the lake. As such, this infestation would not be a candidate for treatment. Treatment methods have recently been used in other lakes with newly reported, isolated populations in shallow waters. More detailed surveys of Fish Trap Lake will be conducted this week.
“Fish Trap Lake is the first lake in Morrison County to be confirmed with zebra mussels,” said Christine Jurek, DNR invasive species specialist in Sauk Rapids. “This new infestation underscores the need for continued diligence in complying with the state’s laws to prevent and curb the spread of invasive species. Boaters and anglers need to be extra vigilant in ensuring their boat and equipment are clean before leaving a lake access, and to contact the DNR right away if they find suspicious aquatic animals or plants.”
The vast majority of Minnesota lakes are not infested by any aquatic invasive species, and less than one-quarter of one percent of Minnesota lakes are known to have zebra mussels. Likewise, most Minnesota anglers and boaters follow the aquatic invasive species laws and do their part to prevent the spread of invasive species. Under law, boaters are required to clean weeds and debris from their boats, remove drain plugs and keep them out while traveling, and dispose of unused bait in the trash.
When a report is made to the DNR, the first step is to confirm that it is an invasive species by obtaining the sample from the individual who discovered it. Once identified, DNR staff immediately survey shorelines and lake bottoms near the reported discovery site in an attempt to confirm the infestation. Sometimes divers are used to search deeper waters. Jurek offers these suggestions to anyone who thinks they may have made a discovery:
- Place specimen in a bag or other container to keep it intact.
- Take a photo of the suspected invasive species.
- Mark on a lake map or GPS the exact location where the specimen was found.
- Contact a local DNR office immediately to arrange transport to the office. DNR regulations allow transport of vegetation and animals to field offices for identification purposes.
- Email a photo and the location of possible discovery to a local DNR office.
Unless it is a sample being transported directly to a DNR office for identification, Minnesota law prohibits the possession or transport of any aquatic invasive species in the state.
Some aquatic invasive species are small and difficult to see at the access. Along with the clean, drain, dispose steps required by law, spraying or drying a boat helps prevent the spread of small species. To remove or kill them before moving to another body of water, especially after leaving zebra mussel or spiny waterflea infested waters, the DNR recommends that boaters either:
- Spray boat with high-pressure water;
- Rinse boat with hot water (120 degrees for two minutes, or 140 degrees for 10 seconds); or
- Dry boat and equipment for at least five days.
More information about zebra mussels, how to inspect boats and other water-related equipment, and a current list of designated infested waters is available on the DNR website.