Assessing a dual-frequency identification sonars' fish-counting accuracy, precision, and turbid river range...

Area of Science:

• Fisheries science
• Aquatic ecology
• Bioacoustics

Background:

• Hydroacoustic fish counting in turbid rivers presents challenges.
• Limitations of traditional sonars include beam fitting, echo discrimination, and individual fish resolution.

Purpose of the Study:

• To evaluate the fish-counting performance of a dual-frequency identification sonar (DIDSON).
• To compare DIDSON's accuracy against other hydroacoustic methods and visual counts in varying water clarity.

Main Methods:

• Assessed DIDSON's fish-counting capability in clear and turbid rivers.
• Compared DIDSON counts with echo counter, split-beam sonar, and video data.
• Utilized tower-based visual counts as a ground-truth reference.

Main Results:

• DIDSON counts closely matched visual tower counts in clear water, showing high agreement.
• DIDSON demonstrated effective operation in turbid conditions, unlike visual methods.
• DIDSON's detection range was reduced in turbid water but remained functional.

Conclusions:

• DIDSON offers superior performance for assessing salmon populations in diverse river conditions.
• Its high-resolution imaging and operational robustness overcome limitations of traditional hydroacoustic tools.
• DIDSON is a valuable tool for fisheries management and research in challenging aquatic environments.