Seeking: New Tools for Non-native Fish Control

Overview:

yet2 is seeking new technologies, tools, or strategies to control or exclude non-native fish species, with a focus on river systems in the desert southwest, including the Colorado and San Juan Rivers. Proposed solutions should reduce non-native fish populations effectively while minimizing impacts on endangered and other native fishes and ideally be cost-effective and have minimal application and maintenance costs.

Current methods such as electrofishing, netting, and chemical treatments are commonly used but have limited efficacy. More efficient, scalable, and species-targeted approaches that can reduce non-native populations long-term are desirable.

 

Background:

Non-native fish pose a significant threat to endangered species in the Upper Colorado River Basin such as the Colorado pikeminnow, razorback sucker, and humpback chub and other native species due to predation and resource competition.

The Basin is heavily impounded by dams, which change the water temperature and chemistry, thus creating conditions that favor non-native species. Current control methods such as mechanical removal via electrofishing and netting, and localized chemical treatments—are labor-intensive, controversial, and often have limited success or negative effects on native species.

Key non-native species of concern include channel catfish, smallmouth bass, green sunfish, brown trout, and walleye. The species of greatest concern varies in priority depending on the river reach but these species are consistently recognized as major threats across the region.

 

Constraints/Requirements:

• Minimal or no impact to endangered and other native fish species
• Effective at controlling or excluding target non-native species
• Suitable for use in desert southwest river systems (Colorado and San Juan Rivers)
• Practical for field deployment, ideally with low application and maintenance costs

 

Possible Solution Areas:

• Genetic technologies such as gene editing (e.g., CRISPR) for population suppression. This may include directly modifying fish genomes to add a negative, heritable trait, but also may include editing something other than fish (i.e. modifying a virus in some way)
• Selective removal techniques targeting specific species
• Monitoring tools integrated with control systems to assess effectiveness
• Novel mechanical methods
• Fish control barriers that prevent passage without harming native species
• Behavioral deterrents (e.g., sound, light, or pheromone-based methods)

 

Desired Outcome of the Solution:

Achieve effective control or elimination of non-native fish species with minimal effort, cost and maintenance and minimal or no impact on native fish populations. Solutions that are field ready or solutions that are promising but still require development are acceptable.

 

Field of Use and Intended Applications:

Applications would be primarily focused on riverine environments in the desert southwest, particularly the Colorado and San Juan Rivers. Solutions may also be applicable to similar desert river habitats where non-native fish threaten native aquatic ecosystems.

 

Previously Attempted Solutions:

• Mechanical methods such as electrofishing and netting (labor-intensive and with limited efficacy)
• Chemical treatments (situation-limited, affects non-target species, controversial)
• Dam related thermal manipulation (e.g., thermal curtain or installing a temperature control device (TCD) on several of the penstocks)
• Strategically placed bubble curtains
• Oxygen deprivation
• Pheromone traps 

 

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