Updated: 3 days ago
We're all aware of whirling disease and its negative effects on trout. But, are you familiar with other aquatic invasive species affecting our rivers? One of these invasive species, New Zealand mudsnails (NZMS), has rapidly expanded its range across the United States, and scientists have long suspected that anglers play a key role in its growing prevalence. The embedded video (above) shows the geographic expansion of NZMS between 1987 and 2019. But are anglers actually to blame?
First, why would we even worry?
New Zealand mudsnails rapidly outproduce native river mollusks and negatively impact mayflies, stoneflies, and caddisflies — some of the most important food sources for trout. Unfortunately, NZMS bind to waders, shoes, and even dogs, and can then be transported across vast distances to new areas via assisted migration. With the ability to self-replicate (asexual reproduction), it takes only one snail to establish a colony in a new waterway. Additionally, if NZMS are the main or only source of food in a river system, trout can starve since they provide very little nutritional value to fish. In fact, mudsnails have been found to survive the digestive process.
Are anglers really responsible for their spread?
When we were outlining this article, we wanted to find a way to test if anglers could be contributing to the spread, at least in the Rocky Mountain states (ID, MT, UT, CO, NM, WY). Long fishing trips where people bounce between popular stretches of rivers could easily explain the spread if an angler's gear isn't appropriately cleaned and dried. We hypothesized that blue-ribbon or gold medal waters (recommended waters) were more likely fished than the other rivers and streams. For our hyp