Design and Initial Validation of an Infrared Beam-Break Fish Counter ('Fish Tracker') for Fish Passage Monitoring.

Area of Science:

• Aquatic ecology
• Riverine ecosystem management
• Bioengineering

Background:

• Effective fish passage monitoring is crucial for river management and fishway performance evaluation.
• Traditional monitoring methods are often costly, invasive, or labor-intensive, limiting widespread use.
• Existing infrared (IR) beam-break counters face challenges with cost and flexibility.

Purpose of the Study:

• To develop and test a novel, low-cost IR beam-break fish passage counter, named FishTracker.
• To assess the system's ability to monitor fish passage, estimate movement, direction, speed, and morphometrics.
• To provide an affordable and flexible alternative to commercial fish monitoring technologies.

Main Methods:

• Developed FishTracker using open-source Raspberry Pi and Arduino platforms.
• Utilized an IR curtain to detect fish passage by analyzing beam interruptions.
• Reconstructed fish silhouettes to estimate movement parameters and morphometrics.
• Conducted field validation with dummy fish, live bleak, and synchronized video of koi carp under varying turbidity.

Main Results:

• Achieved 95-100% detection rates in controlled conditions and approximately 70% in semi-natural conditions.
• Demonstrated consistent body length estimation aligned with established allometric models.
• Identified surface distortion as a primary source of error, preventable by full submersion.
• Showcased remote access capabilities for efficient system management.

Conclusions:

• FishTracker presents a promising, affordable solution for non-invasive, multispecies fish monitoring.
• The open-source design facilitates flexible adaptation and broad deployment, especially in cost-restricted environments.
• This technology supports adaptive river management by enabling effective fish passage evaluation.