Characteristics of gunshot sound displays by North Atlantic right whales in the Bay of Fundy

Abstract

North Atlantic right whales (Eubalaena glacialis) produce a loud, broadband signal referred to as the gunshot sound. These distinctive sounds may be suitable for passive acoustic monitoring and detection of right whales; however, little is known about the prevalence of these sounds in important right whale habitats, such as the Bay of Fundy. This study investigates the timing and distribution of gunshot sound production on the summer feeding grounds using an array of five marine acoustic recording units deployed in the Bay of Fundy, Canada in mid-summer 2004 and 2005. Gunshot sounds were common, detected on 37 of 38 recording days. Stereotyped gunshot bouts averaged 1.5 h, with some bouts exceeding 7 h in duration with up to seven individuals producing gunshots at any one time. Bouts were more commonly detected in the late afternoon and evening than during the morning hours. Locations of gunshots in bouts indicated that whales producing the sounds were either stationary or showed directional travel, suggesting gunshots have different communication functions depending on behavioral context. These results indicate that gunshots are a common right whale sound produced during the summer months and are an important component in the acoustic communication system of this endangered species.