T-Shaped Remote Underwater Video (RUV): A Cost Friendly and Easy Use RUV Technology to Estimate Fish Length in Small...

Area of Science:

• Freshwater ecology
• Alpine stream ecosystems
• Ichthyology

Background:

• Alpine streams are ecologically significant but difficult to study due to remoteness and harsh conditions.
• Traditional fish survey methods are often impractical or invasive in these environments.
• There is a need for non-invasive monitoring tools suitable for high-altitude, fast-flowing waters.

Purpose of the Study:

• To develop and test a lightweight, low-cost remote underwater video (RUV) system for fish monitoring in European Alps' small, high-altitude streams.
• To assess the RUV system's effectiveness in recording fish presence, estimating length, and observing behavior.
• To evaluate the RUV system's suitability for remote deployment and minimal disturbance in challenging aquatic habitats.

Main Methods:

• A T-shaped, lightweight (~1kg) steel-frame remote underwater video (RUV) system was designed and deployed.
• Field tests were conducted in three alpine streams in northwestern Italy in June 2025.
• The RUV system incorporated an integrated reference scale for fish length estimation and recorded video for behavioral analysis.

Main Results:

• The RUV system successfully recorded the presence of salmonid fish species.
• Fish length estimation was feasible using the integrated reference scale.
• Natural fish behaviors, including feeding, were captured, demonstrating the system's observational capabilities.
• The system proved stable in fast-flowing water and portable for remote deployment.

Conclusions:

• The developed RUV system offers a promising, non-invasive method for fish monitoring in challenging alpine stream environments.
• This technology facilitates reliable, permanently recorded observations with minimal ecological disturbance.
• The RUV system has potential applications in species distribution studies, behavioral ecology, and conservation monitoring of alpine freshwater ecosystems.