Behavioral responses of herring (Clupea harengus) to 1–2 and 6–7kHz sonar signals and killer whale feeding sounds

Abstract

Military antisubmarine sonars produce intense sounds within the hearing range of most clupeid fish. The behavioral reactions of overwintering herring ͑Clupea harengus͒ to sonar signals of two different frequency ranges ͑1-2 and 6 -7 kHz͒, and to playback of killer whale feeding sounds, were tested in controlled exposure experiments in Vestfjorden, Norway, November 2006. The behavior of free ranging herring was monitored by two upward-looking echosounders. A vessel towing an operational naval sonar source approached and passed over one of them in a block design setup. No significant escape reactions, either vertically or horizontally, were detected in response to sonar transmissions. Killer whale feeding sounds induced vertical and horizontal movements of herring. The results indicate that neither transmission of 1 -2 kHz nor 6 -7 kHz have significant negative influence on herring on the received sound pressure level tested ͑127-197 and 139-209 dB rms re 1 Pa, respectively͒. Military sonars of such frequencies and source levels may thus be operated in areas of overwintering herring without substantially affecting herring behavior or herring fishery. The avoidance during playback of killer whale sounds demonstrates the nature of an avoidance reaction and the ability of the experimental design to reveal it.

Shelf-scale mapping of sound production by fishes in the eastern Gulf of Mexico, using autonomous glider technology

“…We suspect the 6 kHz sound is related to gas release in clupeids (e.g. Gulf menhaden Brevoortia patronus) (Nøttestad 1998, Wahl berg & Westerberg 2003, Wilson et al 2004, Doksaeter et al 2009, Knudsen et al 2009). Based on the nocturnal characteristics and depth preferences identified in the study, and the reduced list of candidates, efforts can be honed with the aid of fixed acoustic arrays and a video observation system (Rountree 2008) to increase the chances of successful identification in future work.…”

Vocal behaviour and feeding ecology of killer whales Orcinus orca around Shetland, UK

“…During the other encounter, the animals were primarily travelling (a brief bout of foraging was documented prior to the onset of acoustic monitoring) and emitted only 2 whistles in almost 2 h. Herring hear well in the lower part of the frequency band used by killer whales (Enger 1967) and respond to killer whale vocalisations (Wilson & Dill 2002, Doksaeter et al 2009), although their anti-predator strategies to avoid killer whale predation may not be as effective as those of marine mammals (Domenici 2001). Whereas silent travel is rare in killer whales specialising on salmonids (Ford 1989), Icelandic and Norwegian herring-eating killer whales often remain silent when travelling, and this reduction of vocal behaviour may be a result of the better hearing of their targeted prey (Simon et al 2007).…”

Dose-response relationships for the onset of avoidance of sonar by free-ranging killer whales

“…Furthermore, the maneuvering of the observation vessel relative to the whale was kept constant across all experimental conditions, but its proximity might have changed the responsiveness of the whales to sonar. Herring schools present in the same area as these experiments did not respond to sonars at higher received levels (Doksaeter et al, 2009), so it is unlikely that the whales were simply following responses of herring.…”