Justin Perkins,
MCWC Project Manager and Watershed Specialist
The Middle Colorado Watershed Council (MCWC)’s Integrated Water Management Plan has multiple projects to educate and inform the public about nuisance species mitigation. MCWC plans to install signage around gravel pits, public ponds, boat ramps, and river access areas to indicate the prohibition against and the consequences of moving nonnative fish, bullfrogs, plants, and other aquatic species between waterbodies.
Outreach plans include educational information about obtaining a stocking permit, isolating nonnatives, preventing invasive species from escaping to the river, and techniques to minimize reproduction of non-native species.
In partnership with Colorado Natural Heritage Program and Colorado Parks and Wildlife (CPW), MCWC has developed a Nuisance Species Reporting App. This application or web browser on your phone can document and report sightings of nuisance species. The database will be shared with aquatic managers to identify nuisance species hot spots and locations of invasions.
Large scale removal methods of nuisance species are difficult because they have the potential to harm native or non-target populations. Removal efforts only work if all members of the targeted population are removed. If just one breeding pair or a single self-replicating individual is missed, the invasive species can persist. There are several methods for removing nuisance species. Many techniques are used in combination for the best chance of extirpation.
Mechanical techniques are the most common. In aquatic ecosystems electrofishing is a popular method for the removal of nuisance fish species. It can be dangerous, labor, and cost intensive but is highly effective. Biologists seek out key habitats and introduce electric current into the water that temporarily stuns fish. Stunned fish are captured by technicians, undesirable species are sorted and removed from the system. Desirable species recover quickly and are returned to the water unharmed.
Passive techniques such as netting and trapping can also be highly effective. Captures can be selective, but there is a potential for unintended bycatch. Gear can be strategically placed in spawning grounds used by nuisance species to capture adults before reproduction occurs.
Strategic manipulation of flow regimes can be an effective tool. Surged reservoir releases or altered timing can control access to spawning habitats or “wash out” spawning nests of nuisance species.
Biological controls refer to introducing predatory species to aid in removal of invasives. Employing this strategy can be tricky. Managers can’t control what species the predator targets. In this practice it is best to use sterile individuals to control reproduction of the introduced predator.
In areas where nuisance species are established, chemical treatments may be necessary. Introducing a toxic agent to bodies of water to eradicate nuisance species can be highly effective. This technique is extremely labor intensive and requires extensive planning and permitting.
Bounty programs for removal of invasive species encourage anglers to catch nuisance species for a financial reward. Tournaments and competitions are often held with cash and other prizes. These large, community-based efforts towards removal provide a platform to bring awareness and educate the community on the impacts of nuisance species.
CPW’s Aquatic Nuisance Species program is dedicated to protecting Colorado’s natural resources from the introduction of harmful invasive species. ANS staff, partners and volunteers conduct more than 450,000 inspections annually at 72 stations statewide, aimed at preventing the transfer of aquatic organisms between water bodies. Follow basic principles of drain, clean, and dry to prevent accidental transfer of nuisance species.
Preventing introduced species from expanding into fragile aquatic ecosystem may be accomplished by barriers. MCWC is currently planning to install a fish barrier structure on Roan Creek, northwest of De Beque. This barrier will protect an isolated population of native cutthroat trout and sculpins from downstream invaders. By isolating these unique populations, they become protected.
Nuisance species cause severe ecological impacts by competing with and displacing native species. Nuisance species are very costly and require extensive labor to remove. No method of removal is guaranteed. Education and awareness will be key in preventing future introductions of nuisance species. The best approach for managing nuisance species is to prevent species from being introduced in the first place.