North Atlantic right whale (Eubalaena glacialis) recovery strategy: chapter 11

1. Background (cont'd)

1.9. Critical Habitat

Critical habitat as defined under section 2 of SARA is the “habitat necessary for the survival or recovery of a listed wildlife species and that is identified as the species’ critical habitat in the recovery strategy or in an action plan for the species”.

1.9.1. Characteristics of critical habitat

In February 2007, DFO Science conducted a Recovery Potential Assessment (RPA) for right whales in the western North Atlantic. A component of the RPA was the provision of Science advice on the identification of critical habitat for this species. The RPA had two main goals in relation to critical habitat: to establish a generic definition for critical habitat (i.e., define its biophysical attributes); and to identify, if possible, candidate critical habitat areas that would meet this definition (DFO 2007, Smedbol 2007). Much of the information used to develop a description of generic critical habitat has been presented in Sections 1.4.4. and 1.4.5.

The RPA stated that critical habitat for right whales in Canadian waters must allow successful feeding to ensure that sufficient energy reserves are accumulated to support the energetic cost of basal metabolism, growth, reproduction, and lactation. It has been hypothesized in several studies that variation in right whale condition, reproductive rate, and spatiotemporal distribution may be related to successful foraging (Caswell et al. 1999, Kenney et al. 1995, Kenney 2001). For example, during the 1990s the average calving interval increased from 3 to 6 years (Kraus et al. 2001), and during the same period whales that had usually been sighted in Roseway Basin were seen in the Bay of Fundy (Kenney 2001). A consensus working hypothesis proposed to explain these observations (e.g. Patrician 2005) is that during this period copepod concentrations in Roseway Basin were insufficient to meet right whale energy demands, and thus right whales moved into another predictable habitat nearby – Grand Manan Basin. Grand Manan Basin may have lacked the energy reserves necessary to support the increased number of whales in the Bay, and thus may have played a role in the observed reproductive failure (increased calving intervals and fewer births). This period of extended calving intervals was followed subsequently by five years of relatively higher birth rates, a return to shorter average calving intervals. (Kraus et al. 2005) and an increase in the number of right whales observed in Roseway Basin.

Critical habitat has to provide this level of foraging success for right whales on a predictable, interannual basis. Based on what is known about prey preference of right whales and the distribution of their prey, a fairly robust, science-based description of generic critical habitat for right whales was developed through the RPA, as follows: critical habitat includes areas that possess the environmental, oceanographic and bathymetric conditions that aggregate concentrations of right whale prey, especially stage C5 Calanus finmarchicus copepodites, at interannually predictable locations. It is likely that critical habitat in Canadian waters is seasonal in nature. Both right whale abundance and stage C5 Calanus finmarchicus concentrations peak during the late summer and early autumn in the Bay of Fundy and on the Scotian Shelf.  If in the future evidence was gathered suggesting that an area in Canadian waters supported an activity or behaviour, other than feeding, that is vital to life cycle closure, then the definition of critical habitat could be re-evaluated to determine if expansion of the definition is warranted.

1.9.2. Areas of critical habitat

Grand Manan Basin has been identified as critical habitat for right whales. This area matches the characteristics of critical habitat described above by supporting the highest concentrations of copepods in the Bay of Fundy (See Section 1.4.5.). The edges of Grand Manan Basin lie at about 100 m depth, and the maximum depth of the central Basin is approximately 200 m.  The area is exposed to strong tides and the topography and movement of water masses in Grand Manan Basin concentrate the resident copepod population. Every year the Basin area is frequented by a substantial number of the right whales, and in some years up to two thirds of the known population have been sighted in this region. Many females with calves have been sighted in the Bay of Fundy, and a portion of these right whale mothers regularly bring calves to the Bay. Much of the research concerning right whale habitat that has occurred in Canadian waters has been undertaken in and around Grand Manan Basin. This area has been recognized previously as an important area for right whale aggregation with the designation of the Bay of Fundy Right Whale Conservation Area (Figure 1).  

A map providing the boundaries of critical habitat to be protected under SARA (Section 58) is provided in Figure 4. 

Figure 4: Boundary of North Atlantic right whale SARA Critical Habitat for Grand Manan Basin. (Provided by Oceans and Coastal Management Division, DFO) 

Figure 4. Boundary of North Atlantic right whale SARA Critical Habitat for Grand Manan Basin. (Provided by Oceans and Coastal Management Division, DFO) 

The information used to refine the RPA advice, and derive the critical habitat boundaries, focused on available sighting data and sightings per unit effort (SPUE) analysis.  This is due to the limitations associated with the prey abundance and distribution data, particularly at a regional scale. Distribution of North Atlantic right whale sightings is believed to serve as a reasonable proxy for the distribution of the prey field, which in turn is the best available indicator of the location of areas possessing the conditions that aggregate prey. Areas where concentrations of North Atlantic right whales have been sighted on an interannually predictable basis are likely to coincide with areas where interannually predictable prey concentrations occur, and hence are likely to represent areas that possess the conditions necessary to aggregate right whale prey at interannually predictable locations. The boundary encompasses the highest concentration of SPUE (NEAq) and represents approximately 90% of all right whale sightings in the Bay of Fundy from all sources (see Figure 2). For administrative efficiency, a simple shape and prominent coordinates were chosen. As scientific information improves, the boundaries will be reviewed and updated as necessary to reflect the best available information.

Roseway Basin, on the southwestern Scotian Shelf, is another important area of right whale aggregation wherein right whales have been observed feeding and socializing. Mother-calf pairs have been seen in the area, but are rare. Like Grand Manan Basin, this area has been designated as a conservation area for right whales since 1993 (Figure 1). Although the RPA acknowledged the importance of Roseway Basin for right whales, it concluded that there was insufficient data on prey abundance to determine whether this area constitutes critical habitat as per the definition outlined in Section 1.9.1.

However, following the RPA, DFO and scientists from the academic community initiated a collaborative field program in Roseway Basin to address the information gaps and allow evaluation of Roseway Basin as potential critical habitat. This research program was in progress but still unfinished at the time of completion of this recovery strategy; however, it has provided some provisional information. Preliminary analyses of prey field and hydrographical data support the conclusion that Roseway Basin meets the criteria for inclusion as critical habitat for right whales. Based on the available information, critical habitat has been identified in Roseway Basin in this recovery strategy (see Figure 5). Boundaries have been selected to match the “Area To Be Avoided” (ATBA) designated by the International Maritime Organization (IMO; see section 2.7.1). These boundaries were determined in large part by high SPUE in the area, which was also used as a proxy for identifying critical habitat components in Grand Manan Basin (see above). The ATBA boundaries provide two additional efficiencies: they comprise the shape of a simple polygon, and the ATBA will be marked on updated nautical charts provided by the Canadian Hydrographic service. However, the geospatial boundaries of the critical habitat may require refinement once the ongoing research has been completed, and all of the work will have to undergo the process of scientific peer review.

Figure 5. Boundaries of North Atlantic right whale SARA Critical Habitat for Roseway Basin. (Provided by Oceans and Coastal Management Division, DFO) 

Figure 5. Boundaries of North Atlantic right whale SARA Critical Habitat for Roseway Basin. (Provided by Oceans and Coastal Management Division, DFO) 

Table 1 below outlines a schedule of studies for collecting information needed to further identify critical habitat for the North Atlantic right whale. The schedule of studies includes completion of the research activities discussed above to further evaluate the extent of critical habitat in Roseway Basin. This will be a high priority to address through the action planning process.

Other areas of critical habitat for right whales may exist, but detailed data for evaluation are not available. It is important to recognize that right whales have a migratory life history, and must be able to move in and out of critical habitat areas. Migration routes and movement corridors are required for access to habitat in Canadian waters. In addition, a sufficient amount of critical habitat must exist to allow persistence of a recovered population, and not just for current abundance. The schedule of studies outlined in Table 1 includes research activities that should help to determine whether other areas constitute critical habitat for this species. 

1.9.3.  Schedule of studies to identify critical habitat

The following research activities in Table 1 target key knowledge gaps on the habitat requirements of the North Atlantic right whale while seasonally resident in Canadian waters.  Accompanying each activity is an assessment of the overall priority, potential partners, and estimated timing. It is anticipated that implementing the following schedule will yield information to eventually allow for identification of additional areas of critical habitat for this species.

Table 1. Schedule of studies for North Atlantic right whales in Canadian waters to identify critical habitat

Research Activities Priority Start Date Estimated Timing











Critical habitat identification              
Evaluate prey distribution in Roseway Basin to refine critical habitat boundaries. Primary Ongoing x x x    
Evaluate prey distribution in Grand Manan Basin and surrounding areas to refine critical habitat boundaries. Primary Ongoing x x x x x
Evaluate areas outside of the Scotia-Fundy region for potential as critical habitat (e.g. Gaspé area in the Gulf of St. Lawrence) Secondary Ongoing x x x x x
Determine migratory routes of right whales into and out of Canadian waters during their annual migration and evaluate whether migratory routes constitute critical habitat. Secondary Ongoing x x x x x

Other research priorities related to right whale habitat in Canada are described in section 2.5.3 of this document.

Note: Potential partners for the above activities could include but are not limited to the following:

Department of Fisheries and Oceans

Dalhousie University

Memorial University of Newfoundland

Canadian Whale Institute

Grand Manan Whale and Seabird Research Station

New England Aquarium

National Marine Fisheries Service

Aboriginal Representatives

Other Non-Governmental Environmental/Research Organizations

1.9.4 Activities that would destroy critical habitat

According to the RPA, activities that could degrade or destroy critical habitat potentially include oil and gas development, energy development using tidal or current sources, production of intense noise, contamination, or other activities that alter habitat in a way that would affect prey abundance. Climate change and invasive species are also identified as potential threats to critical habitat. Whether a specific activity would destroy critical habitat would depend heavily on the intensity and extent (in time and space) of the activity, how the activity was carried out, and the mitigation measures employed. To constitute destruction of critical habitat, an activity would have to destroy the functionality of the habitat for right whales, either through persistent alteration of the oceanographic and bathymetric features that lead to prey aggregation or persistent exclusion of whales from access to critical habitat. 

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