Western and Central Scotian Shelf Basins IMMA
Size in Square Kilometres
14 046 km2
Qualifying Species and Criteria
North Atlantic Right Whale – Eubalaena glacialis
Criterion A; Criterion B (2); Criterion C (2)
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Summary
The Western and Central Scotian Shelf Basins IMMA is located on the Scotian Shelf off Nova Scotia, Canada. It includes three large oceanographic basins (Roseway, LeHave and Emerald basins), extending approximately 250 km over the western and central Scotian Shelf. This area encompasses a well-known aggregation area for the Critically Endangered North Atlantic right whale (Eubalaena glacialis), where many sightings and acoustic detections have occurred, and where individuals have been observed socializing and feeding. High concentrations of the primary prey of right whales, Calanus copepods, are present in this area. Multiple other marine mammal species are also known to regularly occur within and around these basins.
Description of Qualifying Criteria
Criterion A: Species or Population Vulnerability
The primary Qualifying Species for this area is the North Atlantic right whale (Eubalaena glacialis), which is considered the most endangered of the large whales in the Northwest Atlantic and is listed as Critically Endangered (CR) according to the global IUCN Red List (Cooke 2020). Additionally, the Canadian Species at Risk Act (the Canadian legislation for protection of at-risk species) lists the NARW as Endangered (DFO 2014).
Criterion B: Distribution and Abundance
Sub-criterion B2: Aggregations
Roseway Basin was identified as Critical Habitat for North Atlantic right whales under the Canadian Species at Risk Act based primarily on a concentration of sightings in the area (DFO 2014; Figure 3). Data from field studies provide a strong indication that Roseway Basin is an important aggregation area where right whales have been observed socializing and feeding. Though there have been increased sightings of right whales in the Gulf of St. Lawrence and fewer observations in Roseway Basin in recent years (Meyer-Gutbrod et al. 2022; Record et al. 2019), there has also been a shift in survey effort with relatively limited coverage off southwestern Nova Scotia (DFO 2019, 2020). Ongoing passive acoustic monitoring efforts in and around Roseway and Emerald basins demonstrate that basins of the western and central Scotian Shelf remain important for right whales with relatively high frequencies of acoustic detections in comparison to deeper waters along the Scotian Slope, particularly in spring, summer and fall. In addition to the Bay of Fundy/Grand Manan Basin region, these areas within the IMMA have the highest acoustic presence of right whales off eastern Canada outside of the Gulf of St. Lawrence (Davis et al. 2017, Durette-Morin et al. 2022, Moors-Murphy et al. 2024).
These basin areas overlap the distributional range of many other marine mammal species that occur off eastern Canada. Other baleen whales such as blue, fin, sei, minke (Balaenoptera acutorostrata), and humpback whales (Megaptera novaeangliae); sperm whales; multiple dolphin species including pilot whales (Globicephala melas), Atlantic white-sided dolphins (Lagenorhynchus acutus), white-beaked dolphins (Lagenorhynchus albirostris); and harbour porpoise (Phocoena phocoena), are known to regularly occur within and around the basins (Gomez et al. 2020, Davies et al. 2020, Johnson 2022), but the relative importance of the western and central Scotian Shelf to these other species is not well studied.
Criterion C: Key Life Cycle Activities
Sub-criterion C2: Feeding Areas
North Atlantic right whales have been observed feeding in Roseway Basin. The combination of physical attributes and oceanographic processes that occur in this area concentrate their primary prey, Calanus copepods, within the basin and particularly along the southern slope of the basin, making this basin a uniquely lucrative area for feeding right whales (Davis 2013, 2014). Davis et al. (2014) present evidence to support a strong rationale for expanding the Critical Habitat to the east to better encompass the Calanus distribution around the basin and thus the right whale feeding area. While survey efforts and sightings data have been limited off southwest Nova Scotia in recent years, acoustic detections demonstrate that right whales are detected both within the Critical Habitat boundaries as well as to the east. The relatively high frequency of acoustic detections in Roseway and Emerald basins (Davis et al. 2017, Durette-Morin et al. 2022, Moors-Murphy et al. 2024), combined with Calanus modelling study results (Plourde et al. 2024) suggest that basins of the western and central Scotian Shelf support right whale foraging.
Supporting Information
Cooke, J.G. 2020. Eubalaena glacialis (errata version published in 2020). The IUCN Red List of Threatened Species 2020: e.T41712A178589687. https://dx.doi.org/10.2305/IUCN.UK.2020-2.RLTS.T41712A178589687.en. Accessed on 18 April 2024
Davies K.T.A., T. Ross and C.T. Taggart. 2013. Tidal and subtidal currents affect deep aggregations of right whale prey, Calanus species., along a shelf-basin margin. Marine Ecology Progress Series, 479: 263-282. doi: 10.3354/meps10189
Davies, K.T.A., Taggart, C.T., Smedbol, R.K., 2014. Water mass structure defines the diapausing copepod distribution in a right whale habitat on the Scotian Shelf. Mar. Ecol. Prog. Ser. 497, 69–85.
Davis, G.E., Baumgartner, M.F., Bonnell, J.F., Bell, J., Berchok, C., Thornton, J.B., Brault, S., Buchanan, G, Charif, R.A., Cholewiak, D., Clark, C.W., Corkeron, P., Delarue, J., Dudzinski, K., Hatch, L., Hildebrand, J., Hodge, L., Klinck, H., Kraus, S., Martin, B., Mellinger, D.K., Moors-Murphy, H., Nieukirk, S., Nowacek, D.P., Parks, S., Read, A.J., Rice, A.N., Risch, D., Širović, A., Soldevilla, M., Stafford, K., Stanistreet, J.E., Summers, E., Todd, S., Warde, A. and Van Parijs, S.M. 2017. Long-term passive acoustic recordings track the changing distribution of North Atlantic right whales (Eubalaena glacialis) from 2004 to 2014. Nature Scientific Reports. 7: 13460.
Davis, G. E., Baumgartner, M. F., Corkeron, P. J., Bell, J., Berchok, C., Bonnell, J. M., Thornton, J. B., Brault, S., Buchanan, G. A., Cholewiak, D. M., Clark, C. W., Delarue, J., Hatch, L. T., Klinck, H., Kraus, S. D., Martin, B., Mellinger, D. K., Moors-Murphy, H., Nieukirk, S., Nowacek, D. P., Parks, S. E., Parry, D., Pegg, N., Read, A. J., Rice, A. N., Risch, D., Scott, A., Soldevilla, M. S., Stafford, K. M., Stanistreet, J. E., Summers, E., Todd, S., and Van Parijs, S. M. (2020) Exploring movement patterns and changing distributions of baleen whales in the western North Atlantic using a decade of passive acoustic data. Global Change Biology, 1-30.
DFO. 2014. Recovery Strategy for the North Atlantic Right Whale (Eubalaena glacialis) in Atlantic Canadian Waters [Final]. Species at Risk Act Recovery Strategy Series. Fisheries and Oceans Canada, Ottawa. vii + 68 pp. Available online at: https://wildlife-species.az.ec.gc.ca/species-risk-registry/virtual_sara/files//plans/rs_bnan_narw_am_0414_e.pdf
DFO. 2019. Review of North Atlantic right whale occurrence and risk of entanglements in fishing gear and vessel strikes in Canadian waters. DFO Can. Sci. Advis. Sec. Sci. Advis. Rep. 2019/028.
DFO. 2020. Updated information on the distribution of North Atlantic Right Whale in Canadian waters. DFO Can. Sci. Advis. Sec. Sci. Advis. Rep. 2020/037.
Gomez, C., Konrad, C.M., Vanderlaan, A., Moors-Murphy, H.B., Marotte, E., Lawson, J., Kouwenberg, A-L., Fuentes-Yaco, C., Buren, A. 2020. Identifying priority areas to enhance monitoring of cetaceans in the Northwest Atlantic Ocean. Can. Tech. Rep. Fish. Aquat. Sci. 3370: vi + 103 p.
Johnson, H. 2022. Advancing baleen whale acoustic and habitat monitoring in the Northwest Atlantic. PhD Thesis, Dalhousie University. 178 pp.
Meyer-Gutbrod, E., Davies, K.T.A., Johnson, C.L., Pluorde, S., Sorochan, K., Kenney, R., Ramp, C., Gosselin, J.F., Lawson, J. W., and Greene, C.H. 2022. Redefining North Atlantic right whale habitat use patterns under climate change. Limnology and Oceanography. 9999: 1–164.
Moors-Murphy, H.B., Macklin, G., Evers, C. Stanistreet, J., Colbourne, N., Wingfield, J.E., Xu, J. and Vanderlaan, A.S.M. (2024). Acoustic occurrence of North Atlantic right whales (Eubalaena glacialis) from 2017-2022 off Nova Scotia, Canada. DFO Can. Sci. Advis. Sec. Res. Doc. Accepted for publication.
Plourde, C. Lehoux, J.J. Roberts, C. Johnson, N. Record, P. Pepin, C. Orphanides, R. S. Schick, H. Walsh, C.H. Ross. 2024. Describing the seasonal and spatial distribution of Calanus prey and North Atlantic Right Whale potential foraging habitats in Canadian waters using species distribution models. DFO Can. Sci. Advis. Sec. Res. Doc. 2024/nnn. iv + 71 p.
Record, N., Runge, J., Pendleton, D., Balch, W., Davies, K.T.A., Pershing, A., Johnson, C.L., Stamieszkin, K., Ji, R., Feng, Z., Kraus, S.D., Kenney, R. D., Hudak, C.A., Mayo, C.A., Chen, C., Salisbury, J.E. and Thompson, C.R.S. 2019. Rapid climate-driven circulation changes threaten conservation of endangered north Atlantic right whales. Oceanography 32(1): 162–169.
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