Project background:
In October 2023, the DNR confirmed the presence of signal crayfish in Lake Winona, near-adjacent to Alexandria in Douglas County. This was the first confirmation of signal crayfish in Minnesota waters. The project's main objectives include using mitochondrial DNA to determine the geographic source of signal crayfish and assessing the population status of signal crayfish in Lake Winona and surrounding lakes. Traditional sampling methods and environmental DNA will be employed for this purpose. Based on the determined source population, MAISRC researchers intend to propose likely vectors of invasion and communicate this information to prevent future establishments. The feasibility of future control efforts will be assessed based on the signal crayfish population status determined in the project.
To achieve these objectives, MAISRC researchers plan to extract DNA from signal crayfish tissue. They will then sequence COI and 16S markers using Sanger sequencing to compare them to known populations in native and non-native ranges. Genetic information will be crucial in identifying appropriate environmental DNA sampling assays. In support of the second objective, the researchers will conduct multiple visits to Lake Winona and surrounding lakes to deploy crayfish traps and filter lake water for environmental DNA. They aim to make up to 100 environmental DNA self-preserving filter packs and water sampling kits available to interested volunteers. Collaboration between UMN staff, students, and the Minnesota Department of Natural Resources staff will be essential in field sampling activities.
The importance of this research lies in the impact of signal crayfish on native crayfish, fish communities, and entire ecosystems in their invaded range. The confirmation of multiple signal crayfish in Lake Winona in Douglas County, MN, by the Minnesota Department of Natural Resources in October 2023 raises concerns about population size, reproductive potential, extent of invasion, and source population. Evaluating the current population is critical due to the threat of population expansion and profound ecological impacts. The results of this study will inform lake managers of likely invasion vectors and potential control measures.
Learn more about signal crayfish.
Research findings:
MAISRC researchers carried out an extensive monitoring effort in 2024 to check whether the crayfish had spread or become established.
Over several months, a variety of trapping methods were used in Lake Winona and nearby lakes, but no signal crayfish were physically caught. Researchers collected 142 water samples from Lake Winona and nine surrounding lakes. These samples were tested with environmental DNA (eDNA) analysis, which detects traces of genetic material animals leave behind in the water. Very small amounts of signal crayfish DNA were detected in four samples: two from Lake Winona, one from Lake Henry, and one from Lake Carlos. Each of these results was extremely low and only appeared once in repeated testing.
The combination of trapping and eDNA results suggests that if signal crayfish are present in the region, they exist at very low densities. It is also possible that the eDNA detections came from another source, such as contaminated equipment, water movement between lakes, or discarded bait. Because eDNA can sometimes reveal a species at the earliest stages of an invasion, continued monitoring is important. Early detection gives Minnesota the best chance of preventing signal crayfish from spreading further and harming native species and lake ecosystems.