Potential for population-level disturbance by active sonar in herring

Abstract

For conservation purposes, it is important to evaluate potential population consequences of noise disturbance. Based on maximum reported sound levels of no response to sonar, a mathematical model is used to predict the potential risk to the population of herring (Clupea harengus) when these levels are exceeded. Results show that risk varies with season depending on density of fish. During widespread feeding, the risk of any population consequences is low even at sonar source levels up to 235 dB (re 1 μPa m) and exercise durations exceeding 24 h at sonar frequencies 1-2 kHz. The risk of population effects increases in periods when the population aggregates, but given that our response estimates are conservative, it seems unlikely that today's naval sonar activity will lead to population consequences in Atlantic herring.