Research Document 2021/074

Distribution, movements, and habitat use of northern bottlenose whales (Hyperoodon ampullatus) on the Scotian Shelf

By Stanistreet, J.E., Feyrer, L.J., and Moors-Murphy, H.B.

Abstract

The Scotian Shelf population of northern bottlenose whales (Hyperoodon ampullatus) is listed as Endangered under Canada’s Species at Risk Act. Partial critical habitat was identified for this population in the Recovery Strategy first published in 2010, and three critical habitat areas located along the eastern Scotian Shelf, encompassing the Gully, Shortland Canyon, and Haldimand Canyon, have been designated. In this report, we used several sources of data to examine the distribution, movements and habitat use of northern bottlenose whales within and between designated critical habitat areas. Year-round passive acoustic monitoring conducted with bottom-mounted recorders at two inter-canyon sites revealed the presence and foraging activity of northern bottlenose whales in these areas throughout much of the year, with a seasonal peak in acoustic detections during the spring. Visual sighting records and acoustic recordings collected during vessel-based surveys provided a broader spatial view of species occurrence; these surveys were limited to summer months with effort focused in the canyons. Photo-identification data collected in the Gully, Shortland, and Haldimand canyons in six years of surveys between 2001 and 2017 were used to model the residency and movement patterns of northern bottlenose whales within and between the canyons. Model results suggested that individuals move between canyons over periods of days to months, with an average residency time in the Gully of approximately 20 days. Residency and movement patterns in the other canyons appear to differ from the Gully, but more photo-identification data from these areas are needed to improve the precision of model estimates. We did not find evidence that individuals prefer certain areas, and a low but consistent rate of movement into and out of the Gully suggests that the population may be fully mixing over approximately 6 months. Together, these results indicate a strong degree of connectivity between the Gully, Shortland, and Haldimand canyons and suggest that these areas are open to immigration from and emigration to other outside areas. Inter-canyon areas along the continental slope between the designated critical habitat areas likely represent important foraging habitat for northern bottlenose whales as well as a corridor for frequent movements between the canyons.

Research Document 2021/074 (PDF, 1,514 KB)

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