Abstract Cyanobacterial blooms greatly impact reservoir water quality, posing a challenge to drinking water supply and recreational use. Traditional monitoring approaches, such as chlorophyll-a measurement, often fail to specifically identify cyanobacteria. Although phycocyanin fluorescence sensors (PCY) can detect cyanobacteria accurately, their high maintenance costs and limited coverage limit their practical use in large-scale monitoring. This study investigated the potential of using a conventional fish finder as a low-cost and accessible alternative for cyanobacterial monitoring in the Sanbe Dam Reservoir, Shimane, Japan. Unlike specialized scientific echosounders, conventional fish finders are widely available, affordable, and easy to use, allowing for wider spatial coverage and real-time monitoring. By comparing the acoustic reflection intensity from the fish finders with the PCY data at multiple sampling points, we found a strong correlation between the reflection intensity and PCY values (R 2 = 0.586), particularly at depths where cyanobacteria are abundant (2–6 m). These results suggest that conventional fish finders can efficiently capture the cyanobacterial distribution patterns, thereby providing a practical solution for early bloom detection and comprehensive water quality management in reservoirs.
Kim et al. (Wed,) studied this question.