Movements and distribution of northern bottlenose whales,Hyperoodon ampullatus, on the Scotian Slope and in adjacent waters

Abstract

A small, apparently isolated, and endangered population of~130 northern bottlenose whales (Hyperoodon ampullatus Forster, 1770) is found on the Scotian Slope south of Nova Scotia, Canada. Virtually all previous information on these animals had come from the Gully, a large submarine canyon where the northern bottlenose whales can be reliably found. A ship survey along the 1000 m depth contour in 2001 showed northern bottlenose whales only in the Gully, Shortland canyon (50 km east of the Gully), and Haldimand canyon (100 km east of the Gully). Studies in 2002 reconfirmed the presence of the whales in these other canyons, although densities were about 50% lower than in the Gully. Photo-identifications showed that individuals moved between the Gully and Shortland and Haldimand canyons over periods from days to years, with mean stays in any canyon of about 22 days. However, the population was not fully mixed: at least some individuals had preferences for particular canyons. The sex ratios were similar in all canyons, but males had higher rates of movement between canyons. These results are consistent with the expectations of optimal foraging theory, when the primary resource for females, deep-water squid of the genus Gonatus Gray, 1849, is more temporally stable than the primary resource for males, which is assumed to be receptive females. Haldimand and Shortland canyons are clearly important habitat for this species, and should receive appropriate protection.Résumé : Une petite population apparemment isolée et menacée de~130 baleines à bec communes (Hyperoodon ampullatus Forster, 1770) se retrouve sur le talus continental néo-écossais, au sud de la Nouvelle-Écosse, Canada. Presque toute l'information antérieure sur ces animaux provient de la région du Gully, un grand canyon sous-marin où les baleines à bec communes peuvent être trouvées régulièrement. Un inventaire en bateau le long du contour de 1000 m en 2001 a révélé la présence de baleines à bec communes seulement dans le Gully, dans le canyon Shortland (50 km à l'est du Gully) et dans le canyon Haldimand (100 km à l'est du Gully). Des études en 2002 confirment la présence des baleines dans les deux autres canyons, bien que les densités y soient d'environ 50 % plus basses que dans le Gully. Les identifications de baleines à l'aide de photographies indiquent que les individus se déplacent entre le Gully et les canyons Shortland et Haldimand sur des périodes variant de quelques jours à quelques années avec des durées moyennes de séjour dans un même canyon d'environ 22 jours. La population n'est cependant pas totalement intégrée et au moins quelques individus montrent une préférence pour un canyon en particulier. Le rapport mâles:femelles est semblable dans tous les canyons, mais les mâles ont un plus fort taux de déplacement d'un canyon à un autre. Ces résul-tats s'accordent avec les prédictions de la théorie de la quête optimale lorsque la ressource principale pour les femelles, les calmars d'eau profonde (genre Gonatus Gray, 1849), est plus stable dan...

Movement and foraging behavior of short-finned pilot whales in the Mid-Atlantic Bight: importance of bathymetric features and implications for management

“…Analyses of dive behavior will be useful for examining foraging behavior within and outside of canyons. Shelf break canyons vary considerably in size, and previous studies have suggested that large canyons are likely to support larger numbers of cetaceans than smaller features (Wimmer & Whitehead 2004). The largest canyon within our study area is Hudson Canyon, which is also the northernmost canyon targeted by foraging pilot whales in our study.…”

“…The Gully, a large submarine canyon off eastern Canada, was designated as a Marine Protected Area in 2004, due in large part to a small population of northern bottlenose whales Hyperoodon ampullatus occurring in this region and increasing threats due to oil and gas exploration and development (Whitehead et al 1997, Gowans et al 2000, Wimmer & Whitehead 2004. Hudson Canyon was recently nominated as a national marine sanctuary due to its importance as habitat to a variety of marine organisms, and our results suggest that sanctuary designation in Hudson Canyon could protect important foraging habitat for short-finned pilot whales.…”

Foraging areas, migratory movements and winter destinations of blue whales from the western North Atlantic

“…During the summer, blue whales are reported from several areas in eastern Canadian waters, including the St. Lawrence Estuary (SLE) and the Gulf of St. Lawrence (GSL) (Ramp & Sears 2013), off southern Newfoundland near the French islands of St. Pierre et Miquelon (Desbrosse & Etcheberry 1987), and near or in some canyons along the shelf edge off N ova Scotia (Wimmer & Whitehead 2004, Whitehead 2013. Passive acoustic monitoring systems deployed in US waters also indicated the presence of blue whales both near and off the shelf edge in southern N ewfoundland and the Grand Banks (Clark 1995).…”

Bucking the trend: genetic analysis reveals high diversity, large population size and low differentiation in a deep ocean cetacean

“…It has been assumed that their general biology is similar and most are thought to be deep-diving squid eaters that live in small groups along continental shelf edges. However, much of the information on the biology of these whales is derived from stranded animals combined with extrapolation from data collected on the few species that can be observed at sea (e.g., Wimmer and Whitehead, 2004;McSweeney et al, 2007). Long-term cetacean sighting surveys off the east coast of the United States suggest that beaked whales cluster into ecological niches that are different from all other odontocetes (Schick et al, 2011).…”