Shipboard echosounders negatively affect acoustic detection rates of beaked whales

Beaked whales are cryptic, deep-diving odontocetes that are sensitive to anthropogenic noise. While their behavioral responses to navy sonar have been the subject of extensive study, little effort has been expended to evaluate their responses to other types of acoustic signals, such as fisheries echosounders. From 1 July to 10 August 2013, the Northeast Fisheries Science Center conducted a shipboard cetacean assessment survey, combining visual observation and passive acoustic data collection. Simrad EK60 echosounders were used to collect prey field data; echosounder use was alternated on/off on a daily basis to test for an effect on beaked whale detection rates. The software package Pamguard was used to detect, classify, and localize individual beaked whales. A GLM was used to test the relationship between acoustic detections and covariates; echosounder use negatively affected beaked whale acoustic detection rates, and acoustic event durations were significantly shorter. These results suggest that beaked ...