Performance of acoustic telemetry in relation to submerged aquatic vegetation in a nearshore freshwater habitat

Abstract

Acoustic telemetry is a powerful tool for learning about the movements and ecology of aquatic animals, but proper use requires evaluation of its performance in different environments. Nearshore freshwater habitats are important to many fishes; however, submerged aquatic vegetation (SAV) in these areas influences the performance of acoustic telemetry through attenuation of the transmissions. Despite this, few studies have quantified the influence of SAV on the detection efficiency and range. We conducted range testing and hydroacoustic surveys to assess the seasonal influence of SAV biovolume on the detection efficiency of 180kHz transmitters in the nearshore (<1.5m) habitats of a temperate freshwater riverine ecosystem. The interaction of transmitter–receiver distance and SAV biovolume significantly reduced the detection efficiency of transmitters, which varied with seasonal growth and senescence of SAV. Daily effective detection range (mean±s.e.) varied from 6.85 m±1.98 when SAV coverage was high (mean biovolume 0.98) to 196.08 m±51.89 when SAV was largely absent (mean biovolume 0.01). This study demonstrated the impact of SAV on the detection range of acoustic transmitters, illustrating the need for range testing and consideration in study design and analysis to improve the quality of interpretation of data in vegetated habitats.