lower mountain fork river

The recent discovery of an invasive alga in a southeast Oklahoma river serves to remind anglers of their role in helping prevent the spread of aquatic nuisance species.

Biologists with the Oklahoma Department of Wildlife Conservation and the University of Oklahoma recently confirmed the presence of Didymosphenia geminata, also known by anglers as “Didymo” or “rock snot,” in the Lower Mountain Fork River below Broken Bow Lake. The invasive species is native to North America and thrives in low-nutrient, cold, flowing streams rich in oxygen, such as the Lower Mountain Fork River, the Lower Illinois River and the Blue River.

Didymo starts out as small tufted colonies, but can grow into dense, thick mats that cover large portions of a streambed.

“When it forms extensive mats or produces large blooms, rock snot can outcompete native algae relied on by aquatic insects,” said Curtis Tackett, aquatic nuisance biologist for the Wildlife Department. “That may not sound like a problem, except that those insects provide an important source of food for trout in the Lower Mountain Fork River.”

Tackett said that in some cases, the reduction of available food sources for trout because of competition from invasive species like Didymo can result in smaller fish. Additionally, Didymo can clog water pipes and other flow structures as well as become quite a nuisance to anglers because of how easily it can be snagged by a fish hook.

“Anglers can help prevent further spread of Didymo and other aquatic nuisance species, and it just takes a little bit of effort,” Tackett said. “But that effort can go a long way.”

According to Tackett, the following measures can be taken to prevent the spread of aquatic nuisance species:

• Before leaving a river or stream, remove all clumps of algae and look for hidden fragments.
• Soak and scrub all gear for at least one minute in a two percent bleach solution, or five percent salt solution, or simply use hot water and dishwashing soap.
• If cleaning is not practical, then wait at least 48 hours before contact with another water body after equipment has dried.
• Consider keeping two sets of wading boots, and alternate their use between cleaning and drying. * Avoid using felt-soled waders.
• Avoid wading through colonies of the algae. Breaking up the material could cause future colonies and blooms to occur further downstream.

For more information about the Lower Mountain Fork River trout fishery, log on to the Wildlife Department’s Web site at wildlifedepartment.com.