L.E.Rendell. and J.C.D. Gordon (1999) Vocal response of long-finned pilot whales (Globicephala melas) to military sonar in the Ligurian Sea. Marine Mammal Science. 15(1): 198-204
Summary
During an acoustic survey for odontocetes in the Ligurian Sea Cetacean Sanctuary within the Mediterranean Sea, a loud sonar source was often detected on towed hydrophones, and later observations revealed that these sounds were made as part of a military excercise. Loud sonar signals could be heard during an extended encounter with a pod of long-finned pilot whales (Globicephala melas) when long recordings of their vocalisations were also made, and these have allowed us to investigate the short-term vocal responses of this species to this sound source. Three whistles classes occured significantly more during and just after sonar output than at other times. These results are strongly indicative of a tendency for pilot whales to respond vocally to military sonar pulses. While we cannot prove that these responses had deleterious consequences for the animals involved, it is unlikely that regular induced responses to man-made signals like these could be adaptive. Given these observations, and the fact that the Ligurian Sea has been designated a cetacean sanctuary by France, Italy and Monaco, the possibility of acoustic disturbance of cetaceans in this area by military sonar should be taken seriously.