Its scientific name is Didymoshenia geminata, but anglers know it as didymo, or more simply, rock snot. It is an invasive algae found in 18 states and counting, but Missouri anglers are doing their best to make sure it stays out of their fishing grounds. Didymo tends to show up in colder waters and so far has not been reported in Missouri. That can change quickly. The algae only requires as little as what is in a drop of water to spread, and rivers leading into Missouri from Arkansas have already been infested. The change is a subtle one in the summer, but during winter didymo can form large masses of algae across river beds. The algae collects most noticeably on rocks, hence its name.
“It has never been found in Missouri,” said Paul Spurgeon, fisheries manager for the Missouri Department of Conservation (MDC). “We’re being preventative. We’re trying to stay ahead of the game.”
Spurgeon told The Joplin Globe that the algae is a threat to the many anglers who frequent Missouri rivers and streams. Besides being dangerous for fly fishermen to step on, didymo also chokes native fish of their food supplies and adversely affects underwater fauna. Many anglers find it generally unpleasant.
“It can also make fishing impossible—or nearly impossible,” Spurgeon said.
The MDC began to promote awareness of didymo last year, and the message seems to have been received. Many trout-fishing areas now have cleaning stations where boots and gear are scrubbed down with salt, which kills the algae. Anglers and boaters are being urged to carefully inspect their boats and to clean and dry their vehicles whenever possible. Despite these preventive measures, Spurgeon says that the state’s hatcheries will be conducting tests to see if the algae has invaded Missouri waters.
“We’ll do algae scrapings on rocks. We want to find out: Is it already here? Do we need to ramp up our efforts? If it’s not, we stay with prevention,” Spurgeon said. “Meanwhile, we’re just making sure everyone knows to check. Clean and dry—that’s our motto.”
Image courtesy West Virginia Department of Natural Resources