Science Advisory Report 2020/008

Assessment of the Distribution, Movements, and Habitat Use of Northern Bottlenose Whales on the Scotian Shelf to Support the Identification of Important Habitat

Summary

• The Endangered Scotian Shelf population of northern bottlenose whales consists of fewer than 150 individuals, primarily occupying the eastern edge of the Scotian Shelf. The Gully, Shortland, and Haldimand canyons have been designated as critical habitat for the population.
• Stationary passive acoustic recorders deployed over two years (2012–2014) showed northern bottlenose whale presence and foraging activity in inter-canyon areas throughout the year.
• Vessel-based surveys occurred in summer months over six years between 2001 and 2017 with limited visual and towed-array acoustic effort in inter-canyon areas. Though no northern bottlenose whale sightings occurred, there were acoustic detections during these surveys in inter-canyon areas over multiple days/years.
• Photo-identification studies (2001–2017) showed that some individuals were found in all three canyons, and that individuals typically remained in the Gully for 10–25 days and regularly moved among the three canyons.
• These results indicate that inter-canyon areas function as foraging habitat and movement corridors between canyons and, thus, are important habitat for the population. The areas identified as important habitat can be delineated by the 500 m depth contour and straight lines connecting the southeast corners of the existing critical habitat areas.
• Within the Gully, the highest densities of sightings occurred on either side of the bathymetric feature known as the Southwest Prong, and individuals have been observed moving outside the critical habitat boundary to cross over this feature. This is likely an important area for movement of individuals and habitat connectivity within the Gully and with the inter-canyon areas.
• The features and attributes of the inter-canyon habitat are similar to those of the canyon habitat areas, and include deep water, steep topography, access to prey, an adequate acoustic environment to support foraging and movement, and adequate space to allow the unimpeded movement of individuals.
• Risks to the inter-canyon habitat areas are similar to those identified for canyon habitat areas, and likely include acoustic disturbance, changes to food supply, environmental contamination, and alteration of biological or physical oceanographic conditions. Due to the importance of the inter-canyon areas as movement corridors, physical obstruction preventing movement may also pose a risk to habitat function.
• Analyses presented here were focused on inter-canyon areas and there may remain additional important habitat for the population that has not yet been identified.

This Science Advisory Report is from the February 11-15, 2019, National Marine Mammal Peer Review Committee (NMMPRC) February 2019 Biannual Meeting. Additional publications from this meeting will be posted on the Fisheries and Oceans Canada (DFO) Science Advisory Schedule as they become available.

Science Advisory Report 2020/008 (PDF, 3,947 KB)

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