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Recovery Strategy for the North Atlantic Right Whale (Eubalaena glacialis) in Atlantic Canadian Waters [Proposed]
Species Assessment Information from COSEWIC
- Common name:
- North Atlantic Right Whale
- Scientific name:
- Eubalaena glacialis
- Last Examination and Change:
- May 2003
- Canadian Occurrence:
- Atlantic Ocean
- Reason for Designation:
- The species, found only in the North Atlantic, was heavily reduced by whaling. The total population currently numbers about 3221 animals (about 220-240 mature animals), has been decreasing during the last decade (1990s), and is experiencing high mortality from ship strikes and entanglement in fishing gear. A sophisticated demographic model gives an estimated mean time to extinction of 208 years.
- Status History:
- The right whale was considered a single species and designated Endangered in 1980. Status re-examined and confirmed in April 1985 and in April 1990. Split into two species in May 2003 to allow a separate designation of the North Atlantic right whale. North Atlantic right whale was designated Endangered in May 2003. Last assessment based on an updated status report.
Status in the United States (U.S.)
In U.S. waters, the North Atlantic right whale (originally jointly listed with the North Pacific right whale as ‘northern’ right whale) was first protected in June 1970 by the Endangered Species Conservation Act, which was the precursor to the Endangered Species Act (ESA). The species was subsequently listed as ‘endangered’ under the ESA since its passage in 1973. In the same year, the species was designated as endangered and ‘depleted’ under the Marine Mammal Protection Act(MMPA).
Mandated under the ESA, in 1991 the U.S. Department of Commerce published a Recovery Plan for the Northern Right Whale (including both the North Atlantic and North Pacific right whale), which reviewed knowledge about natural history and human impacts, along with an outline of steps needed to reduce the risks of extinction and enhance the prospects of population recovery (NMFS 1991). The NMFS revised the 1991 plan and developed a separate recovery plan for the North Atlantic right whale population in 2005 (NMFS 2005). Under the ESA and MMPA, the NMFS produces annual stock assessments, which include for each stock the allowable “potential biological removal” (PBR) level. The current PBR for the North Atlantic right whale population is zero whales per year.
Under U.S. law, “critical habitat” of endangered species must be designated and given special protection. Three areas were officially designated in 1994 as “critical habitat” under the ESA for the North Atlantic right whale population: Great South Channel and Cape Cod Bay (both in the southern Gulf of Maine) and the nearshore calving ground off northern Florida and Georgia (Figure 1).
All right whales have been protected from commercial whaling since 1935, and further protected under the International Whaling Commission (IWC) since 1949.
Globally, the right whale was listed as endangered and receives protection under the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). For countries that are signatories to the Convention, including Canada, CITES is an international agreement to ensure that trade in products derived from wild animals and plants does not threaten their survival. Right whales were listed as ‘endangered’ by CITES in 1975 in Appendix 1, which consists of species threatened with extinction; trade of such species is only permitted under exceptional circumstances.
1.2.1. Global Range
The known historical range of right whales, based on whaling records, included a large area of the eastern seaboard of North America. This area extended from northern Florida along the coast to the waters of Atlantic Canada (Figure 1), east to southern Greenland, Iceland, and Norway, and south along the European coast to northwestern Africa (IWC 1986, Mead 1986, Mitchell et al. 1986, Reeves and Mitchell 1986).
Since the 1920s, sightings in the eastern North Atlantic have been sporadic (e.g., in the Canaries, Madeira, Spain, Portugal, United Kingdom, Iceland, and Norway), (Brown 1986, Martin and Walker 1997). In the western North Atlantic, right whales once occurred from Florida to Labrador, including the Strait of Belle Isle and Gulf of St. Lawrence (Aguilar 1986, Reeves et al. 1999, Reeves 2001). Prior to the 1930s they were also encountered and hunted during the summer in pelagic waters, particularly near the eastern edge of the Grand Bank and in an area directly east and southeast of Cape Farewell, the southern tip of Greenland (Reeves and Mitchell 1986).
Figure 1:Western Atlantic range and present day distribution of the North Atlantic right whale. Critical habitat areas in U.S. waters are those areas formally designated under the U.S. Endangered Species Act. (Prepared by K. Lagueux, New England Aquarium)
1.2.2. Canadian Range
Two of the five known high-use habitat areas for this species are located in Atlantic Canada (Figures 1 and 2) with the other three located in the U.S. (Figure 1). In the summer and autumn, North Atlantic right whales are observed suckling, feeding, and socializing in the lower Bay of Fundy between New Brunswick and Nova Scotia, and feeding and socializing in Roseway Basin between Browns and Baccaro Banks on the western Scotian Shelf (Stone et al. 1988, Kraus and Brown 1992, Brown et al. 1995). The Bay of Fundy has been monitored annually since 1980 by researchers from the New England Aquarium (NEAq, Boston, Massachusetts). Monitoring of Roseway Basin has been more sporadic with surveys occurring in 1979-1980, 1985-1993, and 1998-2006 by the NEAq and other research groups.
In addition, there are several other areas of Atlantic Canadian waters where North Atlantic right whales have been seen (Figure 2). For example, North Atlantic right whales have been sighted in deep basins on the eastern Scotian Shelf (Mitchell et al. 1986; T. Cole, personal communication ), in the St. Lawrence Estuary near the confluence of the Saguenay River in 1998 (R. Michaud, pers. comm.), near the Mingan Islands off the lower north shore of Quebec in 1994, 1995, and 1998 (R. Sears, pers. comm.), and more than 30 different individuals over a decade near the mouth of the Baie des Chaleurs south of the Gaspé Peninsula in 1995-1998, and 2000-2006 (N. Cadet, J.F. Blouin pers. comm.). A dead North Atlantic right whale was found near the Magdalen Islands in the Gulf of St. Lawrence in 2001 (NEAq unpublished data), and in the same year an entangled North Atlantic right whale was tracked with a satellite-monitored transmitter along the eastern Scotian Shelf into the Gulf of St. Lawrence to the Magdalen Islands and back to the Scotian Shelf, then south into the Gulf of Maine (Provincetown Center for Coastal Studies, unpublished data). Photographed sightings of North Atlantic right whales during the summer months from the Gulf of St. Lawrence, Gaspé Peninsula, and Labrador Basin, (Knowlton et al. 1992) have been matched to individuals in the identification catalogue for the North Atlantic right whale (Hamilton and Martin 1999).
North Atlantic right whales have not been sighted for more than a century in the historical whaling grounds in the Strait of Belle Isle between Labrador and Newfoundland. Here the species’ range is believed to have overlapped that of the bowhead whale (Aguilar 1986, Cumbaa 1986). Recent analyses of DNA extracted from bone indicate that, contrary to what was previously believed, a very high proportion of the whales taken by the Basque whalers at Red Bay, Labrador, were bowheads (Balaena mysticetus) rather than North Atlantic right whales (Rastogi et al. 2004).
Figure2 : Canadian range of the North Atlanticright whale: 1951-2005. This map is based on individual North Atlantic right whale sightings from the North Atlantic Right Whale Consortium 1951-2005, the St. Andrews Biological Station whale sightings database 1992-2005 and the DFO Newfoundland Region whale sighting database 1975-2003. Dots indicate North Atlantic right whale sightings (with U.S. waters data removed) and the red dotted lines are the boundaries of the exclusive economic zone of Canada, the United States and St. Pierre and Miquelon (France). (Prepared by Oceans and Coastal Management Division, DFO)
1.3 Legal Protection
North Atlantic right whales are listed under Schedule 1, Part 2 of the Species at Risk Act (SARA), and therefore the SARA provisions against the killing, harming, harassing, capturing, taking, possessing, collecting, buying, selling, or trading of individuals or its parts (SARA section 32) and the damage or destruction of its residence (SARA section 33) apply directly to this species. A rationale for not providing a residence description for the North Atlantic right whale has been developed (Smedbol 2007).
Once identified, prohibitions will also be in place against the destruction of the species’ critical habitat (SARA section 58), where critical habitat is defined under section 2 of the Act as“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”. Section 1.9 will address critical habitat as it relates to North Atlantic right whales in Canadian waters.
In addition to SARA, other federal statutes that offer legal protection for North Atlantic right whales and their habitat in Canada include the 1985 Fisheries Act (under Marine Mammal Regulations and a series of habitat protection provisions) administered by the Minister of Fisheries and Oceans. The Marine Mammal Regulations give North Atlantic right whales legal protection from disturbance and deliberate killing, while the habitat protection provisions of the Fisheries Actprohibit works or undertakings that would cause the harmful alteration, disruption or destruction of fish habitat, including the habitat of marine animals.
1.4. General Biology and Description
1.4.1. Name and classification
Common species names
English: North Atlantic Right Whale
French: Baleine noire de l'Atlantique Nord or baleine franche
1.4.2. Taxonomic status
A 1998 International Whaling Commission (IWC) workshop recommended using Eubalaena (the right whales) as a separate genus. The IWC Scientific Committee, after considering genetic and morphological data, decided at its 2000 annual meeting to accept Rosenbaum et al.’s (2000) analysis and proposed nomenclature. It was agreed to retain the generic nameEubalaena for right whales, and to recognize three species, E. glacialis in the North Atlantic, E. japonica in the North Pacific and E. australis in the southern hemisphere (IWC 2001a).
The population structure of right whales in the North Atlantic is poorly understood. A right whale workshop hosted by the IWC provisionally divided the North Atlantic (for statistical purposes) into eastern and western sectors and proposed to treat the area off Cape Farewell (60-62ºN, 33-35ºW) separately. However, photographs of identifiable individuals in the western North Atlantic have been matched with photographs of individuals in the Labrador Basin south-southeast of Greenland and off Norway (Knowlton et al. 1992, IWC 2001b). Given what is currently known about right whale movements and distribution, it is perhaps reasonable to continue to view the whales in the eastern and western North Atlantic as separate “stocks” while recognizing that these animals are highly mobile and sometimes move far outside their well-known habitats in the western North Atlantic (Knowlton et al. 1992, Reeves 2001).
1.4.3. Physical description
Right whales are large, relatively rotund whales, with square chins and a generally black colouration with occasional white belly and chin patches and no dorsal fin (Figure 3). They grow to about 17 m in length, with adult females averaging about 1 m larger than adult males (Allen 1908, Andrews 1908). Adult right whales weigh approximately 60-70 metric tones. A blubber layer up to 20 cm thick serves for both energy storage and insulation (Angell 2005). The head is about 25% of the total body length in adults, up to 35% in juveniles. A strongly arched, narrow rostrum and strongly bowed lower jaws are characteristic of the species.
Gray or black roughened patches of skin, called callosities, are found on the rostrum, behind the blowholes, over the eyes, on the corners of the chin, and variably along the lower lips and jaws (Figure 3). The callosity pattern is unique to each right whale and is used by researchers to identify individuals (Crone and Kraus 1990, Hamilton and Martin 1999, Kraus et al. 1986a). Callosities appear light yellow or cream coloured due to infestations of cyamid crustaceans commonly called whale lice. Baleen plates are black or brown, number 205 to 270 on each side, average 2 to 2.8 m in length, and are relatively narrow (up to 18 cm wide) with fine hair-like fringes facing the interior of the mouth. There are no grooves along the throat. The tail flukes are broad, measuring up to 6 m from tip to tip. In the field, when seen along the axis of the animal, the blow is distinctly V-shaped and can reach 7 m in height.
Figure3 : Schematic depicting an adult and calf North Atlantic right whale and key physical features. (Provided by D. Weil).
1.4.4. Basic biology and ecology
While techniques have been developed to determine the age of toothed whales and some baleen whales, none have been demonstrated as effective for North Atlantic right whales (Kraus and Rolland 2007). Back-calculation from first birth records suggests that North Atlantic right whales routinely live longer than three decades. The oldest known North Atlantic right whale was an adult female who lived to be at least 70 years old based on photographic records from 1935 to 1995 (Hamilton et al. 1998). The mean age of female sexual maturity is not known, but the mean age at first parturition is currently about 10 years (Kraus 2002). The youngest known mother gave birth to her first calf at age five (Knowlton et al. 1994). Sexual maturity in males, estimated from a few known paternities, is about 15 years of age (Frasier 2005). Brown et al. (1994) used genital morphology and genetics to infer that the sex ratio in this population is approximately 50/50.
Most calves are born in the coastal waters of northern Florida and Georgia (Kraus et al. 1986b). Since 1980, the number of calves observed each year has varied from a low of one calf in 2000 to a high of 31 calves in 2001; however there is no apparent trend. Between 1980 and 1992, there were 11-12 calves born per year on average (Knowlton et al. 1994). Since some cows with newborn calves are missed during the winter surveys off Georgia and Florida, complete assessment of a year's calf production requires surveys in the northern feeding areas, particularly Cape Cod Bay, the Great South Channel and the Bay of Fundy. At least two females have had calves over a period of 28 years, suggesting that the reproductive lifespan of North Atlantic right whales is at least that long.
The reasons why mothers and calves choose relatively shallow, nearshore habitat in low latitudes for calving grounds are unknown. The advantages provided by this habitat may include avoidance of predation (i.e. killer whales, Orcinus orca), relative warmth to conserve energy, reduced exposure to surface turbulence, easier orientation and navigation, and fewer disturbances from boisterous approaches by courting males. This same habitat is apparently not critical to females that are not pregnant, adult males, or most juveniles, as these classes are underrepresented on the calving ground. The advantages of this habitat do not persist beyond the calving season, as North Atlantic right whales are almost never seen off the U.S. east coast south of Cape Hatteras (ca. lat 35ºN) between late spring and late autumn (Winn et al. 1986).
The mating system of North Atlantic right whales is not fully understood, but appears to be shaped in large part by the prolonged spacing of calves (3-5 year intervals). Such spacing means that the effective adult sex ratio is roughly one ovulating female to every four males, leading to significant competition among males for mating opportunities. Courtship is the most energetic behaviuor that has been observed with this species. Courtship groups (referred to as “surface-active groups”) may include 40 animals or more, as multiple males try to get close enough to mate with the focal female (Kraus and Hatch 2001). Based upon the limited data available, it appears that the female may have intercourse frequently during a courtship bout with several different males. Males appear to compete for positions next to the female, which are best for taking advantage of each mating opportunity when the female surfaces to breathe (Kraus and Hatch 2001). Social factors, such as the need to participate in the activities of “surface-active groups”, may also influence an individual’s movements.
The seasonal timing and duration of observed courtship activities, from August through October, is puzzling. Calving is first observed in December in the waters off Georgia and Florida and extends through early March. The gestation period for right whales in the North Atlantic is unknown. Best (1994) estimated a 12 month gestation period for southern right whales based on whaling data. Although the seasonal timing of the observed courtship for North Atlantic right whales is not consistent with this estimate, it is possible that courtship in the Bay of Fundy is merely “foreplay,” and that conception occurs elsewhere during December. The resolution of these questions will require better knowledge about the wintering habitats of North Atlantic right whales, and improved methods for evaluating pregnancy in North Atlantic right whales.
Migration and movements
There are five known seasonal, high use areas for North Atlantic right whales. Winn et al. (1986) proposed a six-phase model to explain the seasonal north-south movements of right whales in the western North Atlantic. Most adult females give birth in coastal waters of the southeastern U.S. between Brunswick, Georgia, and Cape Canaveral, Florida, during the winter months (Kraus et al. 1986b). Males and non-calving females are rarely seen in that area, and their whereabouts during the winter remain largely unknown (Kraus et al. 1988). They may be scattered widely along the eastern U.S. coast to at least as far north as Cape Cod Bay (Winn et al. 1986) and the central Gulf of Maine (Northeast Fisheries Science Center unpublished data). There are records of adult and juvenile North Atlantic right whales of both sexes in Cape Cod Bay during the winter and spring, but the number of animals observed annually accounts for less than 30% of the known population (Hamilton and Mayo 1990).
There is a northward migration in the late winter and early spring from the calving ground, with some mother calf pairs moving along the shore. In the spring, aggregations of North Atlantic right whales are observed feeding and socializing in the Great South Channel east of Cape Cod, and in Cape Cod and Massachusetts Bays (Winn et al. 1986, Hamilton and Mayo 1990, Kenney et al. 1995). Directed movements are made in June and July to the feeding grounds in the lower Bay of Fundy and on the western Scotian Shelf where a very high proportion of the known population in seen in at least August and September (Winn et al. 1986). From October, a steady southward migration occurs, with some animals passing through the Gulf of Maine and off Cape Cod (Winn et al. 1986). Recent data have expanded our understanding of the migration and movement patterns of North Atlantic right whales. For example, sightings of North Atlantic right whales in the Bay of Fundy (Laurie Murison, pers. comm.) and in the southeastern Gulf of St. Lawrence (Jack Lawson, pers. comm.) have been reported into late December as have recordings of their vocalizations on Roseway Basin (Mellinger et al. 2007). Summer and autumn sightings of North Atlantic right whales along the Gaspe Peninsula are indicative of transits between the known habitat areas in Atlantic Canada and the Gulf of S. Lawrence (Canadian Whale Institute and NEAq unpublished data).
1.4.5. Habitat Requirements
The North Atlantic right whale is primarily found in coastal and shelf waters. The habitat needs of right whales can be inferred from the seasonal distribution of the population and the types of activities observed in the areas that the animals frequent. Judging by the evidence of segregation among the various classes of whales, habitat requirements appear to differ considerably, depending on a whale’s age, sex, and reproductive status (Brown 1994).
Virtually the entire population moves north for the summer; however since nothing is known about how right whales navigate, it is difficult to judge the importance of oceanographic or topographic features along the migratory corridor(s). Winn et al. (1986) found that calf sightings, even in the higher latitudes, were significantly closer to shore than non-calf sightings. The advantages of a near shore migration would, presumably, diminish by late autumn, when most first-year calves are probably about to be weaned (Hamilton et al. 1995). Opportunities to forage en route might also influence the course taken from one destination to the next.
Defining habitat requirements on the feeding grounds is more straightforward, at least conceptually. Several investigators have attempted to define critical threshold densities of prey necessary for efficient feeding by right whales (see feeding behaviour below). It is assumed that the distribution and movements of right whales during much of the year are driven primarily by the distribution of the large zooplankton that constitutes their prey.
Winn et al. (1986) attempted to define preferred habitat by comparing the distribution of sightings (effort corrected) and behaviour (feeding and socializing) with various environmental factors (water depth, sea surface temperature, and sea floor relief). Their overall conclusions were that right whales preferred water 100 to 150 m deep, usually but not always, over steep bottom slopes. Preferred surface temperatures were mainly in the range of 8 to 15ºC. Gaskin (1987) hypothesized that right whales find preferred feeding conditions in frontal zones between well-mixed and stratified water masses (Murison 1986). Right whales are rarely seen in areas where the sea surface temperature is higher than 18ºC (Kraus et al. 1993).
In the Bay of Fundy, right whales are found mainly in the upper Grand Manan Basin, in waters 90 to 240 metres deep, with surface temperatures of 11 to 14.5ºC and weak thermoclines (Murison and Gaskin 1989, Gaskin 1991). However, it would appear that depth and temperature features are, at best, only proxies for other more directly relevant factors. The driving force is more likely the formation and maintenance of dense concentrations of calanoid copepods, which are, in turn, governed by physical features and processes, such as frontal boundaries, vertical stability and stratification in the water column, and bottom topography (Woodley and Gaskin 1996). When right whales first arrive in the Bay of Fundy in early summer, their distribution tends to be dynamic, with animals often occurring in shallow water close to shore. Similar spreading out occurs in the autumn, when they are sometimes seen in very shallow areas (e.g., around Campobello Island, the ledges south of Grand Manan). These trends are consistent with the lack of dense copepod patches in the Grand Manan Basin, which develop through the summer to a peak in late autumn and then decline (Murison 1986). Outside the Bay of Fundy, satellite-monitored right whales have shown an affinity for edges of banks and basins, upwellings, and thermal fronts.
1.4.6. Feeding behaviour
Right whales swim through the water with their mouths open, filtering zooplankton through their baleen. Baleen is a series of keratinous plates that hang down from the whales’ upper jaw. Because of the morphology of their baleen, and the need to swim slowly to efficiently push large quantities of water through their baleen, right whales are limited to a feeding on a narrow range of zooplankton species (Baumgartner et al. 2007). Right whales locate aggregations of prey at the surface (skim feeding) or at depth (down to at least 200 metres). In the Bay of Fundy, right whales sometimes swim near to the bottom as evidenced by the fact that they surface with mud on their heads. Right whales in the Bay of Fundy, tracked with timed depth recorders, were recorded on feeding dives to depths of 80-175 metres and lasting for 5 to 14 minutes (Baumgartner and Mate 2003).
Right whales in the western North Atlantic feed on a variety of organisms but seem to depend most heavily on the later oil-rich developmental stages (C-IV and C-V, and adults) of the copepodCalanus finmarchicus (Murison and Gaskin 1989, Mayo and Marx 1990, Kenney and Wishner 1995, Baumgartner et al. 2003a). This dependence is evidenced by the copepod hard parts found in faecal material (Kraus and Prescott 1982, Murison 1986, Kraus and Stone 1995) and by the high density of copepods found in the immediate vicinity, or exactly on the paths, of feeding right whales (Murison and Gaskin 1989, Mayo and Marx 1990). As well, evidence is provided by the fact that spring, summer, and autumn aggregations of right whales occur primarily in areas with high densities of these copepods (Kenney et al. 1986, 1995; Wishner et al. 1988).
Copepods form dense concentrations both vertically and horizontally where tides, winds, or prevailing currents form convergences or where water parcels of different temperature, salinity, and density meet to form fronts (Wishner et al. 1988, Kenney and Wishner 1995). Major changes have been observed in the spring and summer distribution of right whales over the last 20 years, suggesting that they respond to changes in prey density. For example, they appeared to favor of the Bay of Fundy over Roseway Basin between 1993 and 1997 (NEAq, unpublished data) and no right whales were found during surveys of the Great South Channel in 1992 (Kenney 2001).
Zooplankton organisms are not homogeneously distributed, but instead usually occur in "patches" in the water column. When sampling in the discrete layers targeted by whales in the Bay of Fundy, Baumgartner and Mate (2003) and Baumgartner et al. (2003b) found copepod abundances that were several orders of magnitude above background levels. The spatial variability in their occurrence was associated with a layer of mixing at the bottom and their depth of dive suggested that they are targeting dense concentrations where conditions help to form discrete, vertically-compressed layers of copepods. Concentration may be further enhanced as zooplankton seek preferred intensities of light or other physical factors during diurnal vertical migrations. The mechanisms underlying the formation and maintenance of zooplankton patches are not well understood and are an active area of research both in the right whale research community and in the broader field of biological oceanography.
Right whales are, therefore, highly dependent upon a narrow range of prey, which occur in highly variable and spatially unpredictable patches in the Atlantic ecosystem. The four known northern feeding habitats apparently have conditions that are conducive to the creation of highly concentrated patches of copepods. There is, however, substantial inter-annual variability in copepod production, and thus in right whale abundance, in each of these areas (Brown et al. 2001, Kenney 2001). Right whales have adapted to this unpredictability with a large caloric buffer in the form of blubber (Moore et al. 2001) and an ability to travel long distances in relatively short periods of time (Mate et al. 1997, Slay and Kraus 1999, Kraus 2002, Baumgartner and Mate, 2005).
1.5. Biological Limiting Factors
1.5.1. Life History Strategy
Right whales are typical of species that exhibit long life spans, mature relatively late and produce fewer, larger young. These characteristics result in relatively long generation times. Offspring are typically relatively large and develop slowly, requiring a fair degree of parental investment.
Such species are called K-selected species because they tend to do well in competitive conditions when their population size is near carrying capacity (K). However, a life history strategy that includes long generation times and low annual reproductive rates leaves the species susceptible to increases in mortality (e.g. human induced). Over longer periods these species are prone to extinction if mortality remains high. Population recovery can require long periods (on the order of decades) due to the low reproductive rates.
1.5.2. Low genetic diversity
While research has shown that the North Atlantic right whale population is more genetically diverse than would be expected for such a small population, nonetheless its reproductive success is diminished by low genetic diversity. The ongoing genetic analyses of the right whale have shown that this species has among the lowest levels of genetic diversity identified in a large mammal at all markers tested to date, including: minisatellite markers (Schaeff et al. 1997); mitochondrial DNA sequences (Malik et al. 2000); and microsatellite markers (Waldick et al. 2002). These findings have led to the hypothesis that the low level of genetic variability may be at least partially responsible for the reduced reproductive performance observed in this species. Therefore, because this species has such low levels of genetic variability there is an increased probability that mating pairs will have similar genetic profiles, which could subsequently result in a high rate of foetal loss and a reduced reproductive performance. Although conservation actions could not likely be implemented to mitigate the negative impacts of genetic characteristics on reproduction, this information will provide an estimate of the degree to which reproductive success and species recovery are limited by intrinsic factors.
Analyses of the genetic characteristics of the extant population did not detect any evidence of a genetic bottleneck (Waldick et al. 2002). These tests are only sensitive to recent events and suggest that a genetic bottleneck has not occurred since approximately the 1800s. Additionally, genetic analyses of historic specimens from the 1500s suggest that the impact of Basque whaling on the North Atlantic right whale was much less than has previously been assumed, and that small population size may be a long-term characteristic of this species (Rastogi et al. 2004, Frasier et al. 2007). In light of these recent data, suggesting that this species had a small population size prior to whaling, the idea of nutritional limitations becomes more feasible.
One hypothesis is that the last ice age reduced this population to a relatively small size, and additionally altered the environment in such a way that the western North Atlantic could only support a small population. Under this scenario, nutritional factors, as well as genetic factors associated with long-term small population sizes, would be expected to influence present-day population trends. Although the hypothesis of nutritional limitations (i.e. reduced availability of right whales’ copepod prey) remains to be tested, there is evidence that genetic characteristics are influencing reproductive success as would be expected under this scenario (Frasier et al. 2007).
1.5.3. Low reproductive rates
The reduced reproductive performance of the right whale is recognized as one of the primary factors limiting the species’ recovery. In a recent analysis of calving intervals between 1982 and 2006, Kraus et al. (2007) observed significant variation in the amount of time between births by individual females. The short-term effects of reduced reproduction include an increase in the average inter-birth interval from ~3.5 years in the 1980s to ~6 years in the 1990s (Kraus et al. 2001), although since 2001 this average appears to be returning to approximately 3 years for some of the adult females (Kraus et al. 2007).
The long-term reproductive performance of this species is lower than expected, as is demonstrated in the lower number of calves born per year that would be expected given the population parameters. The current population size estimate is about 300-350 individuals (NMFS 2005), the sex ratio is ~50:50 (Brown et al. 1994), and it is estimated that 60% of the females are adults (Hamilton et al. 1998). This results in an estimate of ~90-105 adult females in any given year. Therefore, since females are capable of giving birth once every 3 years (Knowlton et al. 1994, Kraus et al. 2001), it is expected that ~30-35 calves should be born per year, instead of the average of 11 in the 1980s and 1990s (Kraus et al. 2001) and 23 between 2001 and 2005 (Kraus et al. 2007) It appears that a high percentage of adult females have either never given birth or have had only one offspring.
1.6. Economic and Cultural Significance
The right whale is an important resource for several coastal communities in Atlantic Canada (see whale watching below). The right whale is a large, rare species that is becoming better known amongst the general public. There has been some media coverage about conservation issues and actions in Canada and the United States. The species almost certainly has substantial non-consumptive value to Canadian society because members of the public want to preserve the species for future generations (legacy value) or just derive value from knowing the species exists even though they will never personally see or ‘use’ the species (existence value).
1.6.1. Whale watching
Whale watching is an important part of the growing ecotourism sector along the shores of New Brunswick and Nova Scotia, particularly in the West Isles and Grand Manan, New Brunswick and Digby Neck, Long Island and Brier Island, Nova Scotia areas. Right whales are one of four large whale species commonly observed in the Bay of Fundy. The industry in New Brunswick and Nova Scotia experienced rapid growth in the mid- to late 1990s. In 1998, there were 140,000 individual whale-watching trips in all of New Brunswick and Nova Scotia with $5.12M in direct expenditures (Hoyt 2000). Whale watching is also an important economic industry in Québec with occasional sighting of North Atlantic right whales. The influence of right whale abundance on the overall viability of whale watching tour operators is not currently known as other whale species are also seen. However, the public’s awareness and sensitivity toward right whale issues is enhanced through the educational component of whale watch excursions.
Right whales were found historically, and continue to be seen in the areas of Mi’kmaq, Passamaquoddy, and Maliseet Aboriginal communities. Harvesting of marine mammals is a tradition of Aboriginal communities in many parts of North America that reaches back several thousand years. Historical and present-day uses and values of the North Atlantic right whale to Aboriginal communities are not known but there are currently no harvests for food, social and ceremonial purposes.
1.7. Population Size, Structure and Trends
The population of right whales in the western North Atlantic was estimated in the COSEWIC report (2003) to number about 322 animals. The COSEWIC report did not present the methods used to estimate population size, however the estimate represents the number of catalogued right whales thought to be alive in 2003. Kraus and Rolland (2007) suggest that currently, there are no reliable estimates of right whale population size beyond stating that about 350 animals remain. In terms of trends, the population appeared to have been declining in the 1990s (Caswell et al. 1999, Fujiwara and Caswell2001, Fujiwara 2002, Caswell and Fujiwara 2004), but only data through 1998 were used in those analyses.
The North Atlantic right whale population is currently assumed to represent one interbreeding population; however this topic has yet to be adequately addressed. It is recognized that there are great differences in the habitat use patterns of different individuals (Brown et al. 2001), and that the population shows significant signs of structuring or fidelity in relation to nursery use by mothers (Malik et al. 1999). However it is not known if these patterns also result in the population being structured into two or more subpopulations separated by some degree of reproductive isolation. Identifying cryptic population structure such as this represents one of the primary concerns in conservation biology because conservation actions often fail in situations where structuring exists but is undetected or unaccounted for (Taylor and Dizon 1999). Testing for structure will identify if this species can be managed as one interbreeding population, or if it represents more than one continuous gene pool, with each sub-population requiring different management considerations. Additionally, these data will reveal previously hidden information on social structure, reproductive biology, and habitat use patterns. The tools necessary for addressing this issue (genetic profiles at a large number of variable loci) are now available, and this work is currently underway.
The North Atlantic right whale population was probably even smaller in the past than it is today (Reeves et al. 1992, Reeves 2001). Malik et al. (1999) found only five matrilines represented in the mitochondrial DNA (mtDNA) from over 200 animals sampled in the western North Atlantic population. Since mtDNA is inherited only from the mother, this suggests that the population went through a very small "bottleneck" at some time in the recent past. It is important to recognize, however, that each mtDNA haplotype could have been represented by more than one female and therefore the study by Malik et al. (1999) does not necessarily imply that only five female North Atlantic right whales existed at some point in the past.
Based on analyses of stranding, entanglement, and photographic data, Kraus (1990) and Kenney and Kraus (1993) estimated that mortality ranged between 5% and 18% during the first three years of life. Moore et al. (2007) determined that calves and juveniles are at significantly greater risk of dying than adults in a given year, though their analysis of all known mortality events shows no particular distribution among age classes or between sexes. Adult mortality rates are very low, probably less than 1% annually, although population modelling studies (Fujiwara and Caswell 2001, Caswell and Fujiwara 2004) indicate that adult female mortality rates are substantially higher, and are the major contribution to the lack of recovery (Fujiwara and Caswell 2001, Kraus 2002).
The North Atlantic right whale population has been subject to significant anthropogenic mortality (Knowlton and Kraus 2001) and has experienced a significant decline in reproductive rates during 1990s (Kraus et al. 2001, Caswell and Fujiwara 2004). In the period from 1980 to 1992, annual estimates of population size back-calculated from data on calving and mortality indicated a steady increase from 255 in 1986 to 295 in 1992, implying a mean net annual growth rate of 2.5% (Knowlton et al. 1994). Fujiwara and Caswell (2001) however calculated the asymptotic population growth rates from 1980 to 1995 and found that the rate had, in fact, declined from 1980 to 1995. Those authors suggested that if the 1995 growth rate were maintained, the population would become extinct inperhaps as little as 100, and on average about 200 years. This latter analysis is currently thought to best represent the population growth rate trend for that time period (Kraus et al. 2005). The eastern North Atlantic population probably numbers in the low tens of animals, at most, and is certainly too small to offer any hope of a “rescue effect” on the western population.
Since whaling ended in the 1930s the most obvious threats that are potentially depressing the growth rate of the North Atlantic right whale population are strikes by vessels and entanglements in fixed fishing gear. Of 75 reliably documented right whale deaths between 1970 and January 2007, eight (~11%) were traced to entanglements in fishing gear, 28 (37%) were traced to collisions with vessels, 21 (28%) were attributed to "unknown causes" and 18 (24%) to "neonatal mortality" (Knowlton and Kraus 2001 and NEAq unpublished data). Twenty-one of the 28 known ship strikes (75%) have occurred over the period 1991 through January 2007 and represent 50% of the known right whale mortalities for this period. The actual total number of deaths resulting from human activities is unknown; however, it is almost certainly higher than the observed number because not all carcasses of right whales are found. For example, carcasses of right whales that die as a result of entanglements in fishing gear may be more likely to sink at sea because of the decreased health of the animals and subsequent loss of blubber mass and thus it has been suggest that up to two-thirds of human-caused right whale deaths may go undetected (Moore et al. 2007).
The only "natural" mortality currently observed is neonatal mortality, though it should be presumed that natural deaths from old age occur as well. The category of “unknown” deaths includes those animals for which the carcass was not retrieved, the carcass was too decomposed to identify a causal factor, or no obvious factor was found despite a detailed necropsy.
The mortality from vessel strikes and entanglements would be particularly significant if it was biased toward females. Given that females accompanied by calves are usually observed in coastal waters where fishing gear and ships are more common, it is plausible that adult females would be more vulnerable to the threats of ship strike and entanglement. Overall, known deaths in the last five years reflect a female bias (NEAq unpublished data).
1.8.1. Historical threat - whaling
Right whales played a large role in the development of the whaling industry in eastern North America. The name of the right whale may have come from whalers who thought that it was the "right" whale to kill from an economic perspective, although the exact origin of the common name is unknown. They were easy to approach, floated after death and provided large amounts of products such as oil and baleen. As a consequence, the population was reduced to very low levels and was commercially extinct in the 19th century. The population was legally protected from commercial whaling in the 1930s.
As early as the 14th century, Basque ships were whaling off the waters of Atlantic Canada and are thought to have targeted species such as right whales. Whaling in the United States was the centre of the world whaling industry during the 18th and 19th centuries. In the western North Atlantic, right whales were hunted in coastal waters from Florida to Labrador, including the Strait of Belle Isle and Gulf of St. Lawrence (Aguilar 1986, Reeves et al. 1999, Reeves 2001). They were also encountered and hunted during the summer in pelagic waters, particularly near the eastern edge of the Grand Bank and in an area directly east and southeast of Cape Farewell, the southern tip of Greenland (Reeves and Mitchell 1986). There is only limited evidence of historical whaling for right whales the present-day high-use areas; the Bay of Fundy (Reeves and Barto 1985), the Scotian Shelf (Mitchell et al.1986), and the Great South Channel (Reeves and Mitchell 1986, Reeves et al.1999).
It is interesting to note that no right whales have been reported for more than a century in the supposed historical Basque whaling grounds in the Strait of Belle Isle between Labrador and Newfoundland, where the species’ range is believed to have overlapped that of the bowhead whale (Aguilar 1986, Cumbaa 1986). It has generally been assumed that the balaenids hunted in summer in this region were right whales, while those hunted from late autumn through spring were bowheads (Tuck and Grenier 1981, Cumbaa 1986, Reeves and Mitchell 1986). Recent analyses of DNA extracted from bone material indicate that a very high proportion of the whales taken by the Basque whalers at Red Bay, Labrador, were bowheads rather than right whales (Rastogi et al. 2004 and (Frasier et al. 2007).These results contradict earlier views that Basque whalers harvested equal proportions of right whales and bowhead whales in that area, in turn suggesting that the right whale population has been relatively low since before commercial hunting (Frasier et al. 2007).
1.8.2. Vessel strikes
The importance of vessel collisions as the leading cause of mortality for right whales has been recognized since the 1970s (Reeves et al. 1978, Kraus 1990, Kraus et al. 2005, Moore et al. 2007). Since 1970, there have been 75 carcasses reported, at least 28 of which have died as a result of a ship strike (Knowlton and Brown 2007). Twenty-one of the 28 ship strikes (75%) have occurred over the period 1991 through January 2007 and represent 50% of the total right whale mortalities for this period. In addition to the outright mortality, about seven per cent of the living population was seen to have “major wounds” on the back or tail peduncle caused by propellers. Thus the actual total number of deaths resulting from vessel strikes is unknown; however, it is almost certainly higher than the observed number because not all injured right whales are found and the poor condition of some carcasses prevents conclusive determination of the cause of death (Moore et al. 2007). Moreover, the morbidity, lowered productivity and decreased longevity of animals with “nonfatal” or “possibly fatal” injuries (e.g., propeller cuts, deep gashes, severed flukes) must be taken into account when evaluating the total impact of vessel collisions. Seven of the 28 (25%) fatalities traced to vessel strikes are known to have taken place in Canadian waters between 1987 and 2006.
The mechanisms involved in a whale’s ability to detect and take evasive action to prevent being struck by a vessel are poorly understood. Evidence suggests that the hearing range of right whales encompasses frequencies produced by vessels (Knowlton and Brown 2007). However, it may not be too surprising that right whales do not always take successful evasive action when vessels approach them, since the sound produced by most vessels propagates toward the rear and sides of the vessel; the area forward of the bow may be the quietest location. The effect of noise masking by meteorological conditions (wind, waves and precipitation) is not known. It has also been argued that for an animal with such a long lifespan, there has been no opportunity to evolve a response to vessels, since vessel traffic is a relatively new addition to their habitat, and vessel speeds have increased in the past several decades.
Most of the areas heavily used by right whales in the western North Atlantic are in or near major shipping lanes serving ports in the eastern United States and Canada (Knowlton and Kraus 2001). There are, however, stewardship measures at our disposal that will help reduce the threat of vessel strikes in Canadian waters. For example, researchers used evidence from extensive survey work in the Bay of Fundy and limited radio tracking to show that right whales were found most frequently and in highest concentrations in the deepest part of the Bay of Fundy, which placed them in or near the Bay of Fundy Traffic Separation Scheme (Knowlton and Brown 2007, Mate et al. 1997). As the whales are highly mobile, their wanderings frequently take them across other shipping routes, including Roseway Basin on the western Scotian Shelf and ones east of Halifax (Mate et al. 1997). The Bay of Fundy Traffic Separation scheme was amended to reduce the relative probability of vessel/right whale interaction by 80% (Knowlton and Brown 2007).
Recent investigations seek to understand the influence of both vessel size and vessel speed on injury or mortality of right whales. It is known that both small and large vessels can cause death and life-threatening injury to right whales, such as the observed morbid condition of a whale that had been struck by a 12.8 meter long recreational vessel (Knowlton and Brown 2007). As more strikes are documented where the vessel speed is known, findings suggest that vessels traveling at less than 13 knots (26 km/h) may provide right whales with a greater likelihood of avoiding serious injury or death (Knowlton and Brown 2007). Vanderlaan and Taggart (2007) analyzed right whale vessel strike data and concluded that at vessel speeds above 15 knots (28 km/h), lethality to whales approaches 100%. Conversely they found that for whale strikes by vessels travelling at less than 11.8 knots (22 km/h), lethality dropped below 50%.
1.8.3. Entanglement in fishing gear
Entanglement and entrapment of right whales (and other cetaceans) in fixed fishing gear has been known as a hazard for decades. For example, as early as 1909, a young right whale became entangled in a fish-trap in Provincetown Harbor (Massachusetts), allowing local fishermen to kill it with a bomb-lance (Allen 1916). Reports in the 1970s of whales entangled in netting and lobster lines, and trapped in herring weirs, were regarded as "exceptional" events by Reeves et al. (1978). But the more rigorous evaluations since then by Kraus (1990), Kenney and Kraus (1993), and Knowlton and Kraus (2001) have shown that interactions with fishing gear are considered a major source of serious injury and mortality and an important factor in slowing the right whale population's recovery (Kraus et al. 2005).
The most recent analysis of scarring showed that more than 75% of right whales have scars indicative of an entanglement at some time in their lives and that the rate of scar accumulation increased in the 1990s (Knowlton et al. 2005). While no sex bias was apparent, there is an age bias: juvenile right whales experienced a disproportionately higher number of entanglements than adults (Knowlton et al. 2005). The attribution of entanglements to a particular geographical location or gear type is difficult to determine because the whales are highly mobile and the entangling gear retrieved is often unmarked. However, it has been shown that the types of fishing gear most often implicated in right whale entanglements are the vertical and horizontal lines used in fixed gear fisheries (i.e. gillnets and pot gear) in Canadian and U.S waters (Johnson et al. 2005). There are no documented entanglements of right whales with near shore aquaculture operations. However, the possible risk of entanglements with larger offshore aquaculture facilities with bottom to surface buoy systems is unknown.
Since 1988, at least two right whale mortalities from entanglement can be attributed to fishing gear traced to Canadian fishing operations (Knowlton and Kraus 2001, NEAq unpublished data). The actual total number of deaths resulting from entanglements range-wide is unknown. However, it is almost certainly higher than the observed number in Canadian and US waters as indicated by the analysis of entanglement data from 1980 through 1999 that documented eight right whales, that were last seen alive but with potentially fatal entanglements, that are presumed dead (Knowlton and Kraus 2001).
In Atlantic Canadian waters, researchers are using right whale sighting data and logbook data from the fixed gear fisheries to determine where there is a seasonal overlap between the whales and fishing operations (Taggart et. al. 2005). In the past, most fishing activity was thought to occur at a time of year when right whales were not present (WWF/DFO 2000). However, due to more comprehensive sighting data, examination of fishing gear retrieved from entangled right whales, and the emergence of new fixed gear fisheries that are carried out in the summer and autumn, it is clear that there is a greater risk for right whale entanglement in Canadian waters than was previously thought.
Disentanglement efforts in Canada and the United States have resulted in the freeing of some right whales and the release of a few entrapped in herring weirs (NEAq, PCCS unpublished data). Disentanglement of free-swimming right whales is notoriously difficult, often unsuccessful and does not guarantee survival of the whale in question, however, these efforts should continue until changes in fishing practices are implemented that are successful in eliminating severe entanglements.
1.8.4. Disturbance and habitat reduction or degradation
General references have been made to the possibility that habitat degradation is contributing to the North Atlantic right whale population’s failure to recover more rapidly (Reeves et al. 1978, Kraus 1985, Gaskin 1987, Kraus et al. 2005, Kraus and Rolland 2007). The concept of habitat quality reduction or degradation includes a host of short and long term phenomena from exposure to contaminants from marine and land-based activities, as well as exposure to excessive noise, and to changes in the food supply as a result of human activities.
Two points must be made when discussing habitat degradation in the context of right whale recovery strategies. First, it cannot be assumed that right whales simply relocate once a threshold of disturbance has been reached in a part of their range. The cost of such relocation is likely to take the form of reduced reproductive success or increased mortality, or both. Second, the effects of various types of degradation are likely to be cumulative or synergistic, or both. While cumulative and synergistic effects are potentially important, (Bunch and Reeves 1992, Pearce and Wallace 1995, Mangel et al. 1996), it is extremely difficult or impossible to document and describe them using empirical data.
As specialists that prey only on relatively small zooplankton that are low in the food web, right whales are less prone than most other baleen whales to accumulate large body burdens of organic contaminants (Woodley et al. 1991). Moreover, baleen whales generally have lower contaminant concentrations in their tissues than the toothed whales (O’Shea and Brownell 1994). If contaminants are affecting the survival or reproductive success of any baleen whale population, the effects have yet to be detected and described. It is important to emphasize that this does not mean there is no effect. It is extremely difficult to prove a causal link of this kind in a large, rare, wild mammal, for which standard experimental or epidemiological approaches are impossible. Even if there were no direct adverse effects on right whales from exposure to contaminants, the possibility of indirect effects brought about by their food supply could not be ruled out.
While the number of harmful algal blooms in the northwestern Atlantic has increased in recent years, and humpback whales (Megaptera novaeangliae) deaths in Cape Cod Bay have been attributed to biotoxins in their prey fish, there has never been a recorded case of toxic algal blooms affecting right whales (Rolland et al. 2007). In theory, saxitoxins – organisms responsible for paralytic shellfish poisoning – pose a risk to right whales. The whales’ feeding mechanism, filtering their plankton prey through baleen, is likely to prevent the small algal cells from being ingested (Rolland et al. 2007).
The risk posed to right whales from endocrine disrupting chemicals has not been investigated. Because of their use of coastal habitats, it is possible that right whales are exposed to some of these chemicals from run-off, sewage outflows or other sources. Exposure to endocrine-disrupting chemicals during early development has been shown to alter reproductive and immune system function in lab and domestic animals, humans and wildlife (Colborn et al.1993). Some of the current use chemicals of possible concern for right whales include: the polybrominated diphenyl ethers (flame retardants), phthalate esters (plasticizers), alkylphenol ethoxylates (surfactants) and organotin compounds (anti-fouling agents: Reeves et al. 2001).
Organochlorines, especially toxaphenes, DDT, and PCBs are present in the blubber of right whales in the western North Atlantic, but the levels are not considered high enough for great concern (A. Westgate, pers. comm.). The trends of organochlorine concentrations follow the typical cetacean pattern, with low levels in calves, slightly higher levels in juveniles, highest levels in adult males, and low to medium levels in adult females (Woodley et al. 1991, A. Westgate pers. comm.). Females offload organochlorines to their calves during gestation and lactation. Males, in contrast, continue to accumulate these compounds throughout their lives.
In Atlantic Canada there are several existing and potential point and non-point sources of contaminants. These include vessel discharges, aquaculture operations, land run-off, oil and gas activities, and dredging (through remobilization of contaminants) to name a few. Gaskin (1987) called attention to the fact that current circulation in both the Bay of Fundy and Gulf of Maine, where right whales feed, is semi-enclosed for at least part of the year. This means that contaminant gradients could become established from the inshore to the offshore regions. Recent reviews of information on contaminants in the Bay of Fundy have shown clear cause for concern (Percy et al. 1997). A wide array of contaminants, including those described above, are present in the environment and in the food web.
For right whales, like all baleen whales, hearing is critical to their ability to communicate, navigate and locate food. While extensive research has been conducted on the sound production and behaviour of humpback whales and southern right whales, it is only recently that greater focus has been placed on these aspects of North Atlantic right whale ecology (Parks and Clark 2007). While ambient noise levels in right whale habitat can at times be high, for example due to storm and wave activity, increasing levels of human-caused noise are a cause for concern. The two relevant components of noise are duration and intensity. Some sounds are very loud but of short duration (for example some kinds of sonar or seismic activity), while other sounds are loud and also of long duration (e.g. commercial shipping traffic) (Parks and Clark 2007).
The effects of increased noise on marine mammals are varied and may include habituation, behavioural disturbance (including displacement), temporary or permanent hearing impairment, acoustic masking, and even mortality (Richardson et al. 1995). Increased noise can mask important social communication (e.g. mating calls, mother-calf interactions), limiting the range over which right whales can communicate (Parks et al. 2006), which in turn may reduce mating opportunities (e.g. beluga, Delphinapterus leucas Erbe and Farmer 1998).
A range of anthropogenic noises in the marine waters of Atlantic Canada produce underwater sounds within the frequency range detectable by right whales (estimated to be 12Hz to 22 kHz, with fundamental frequency of sounds produced by right whales primarily between 50 Hz -2 kHz; Parks 2003). Within the high-use right whale habitat areas in Canada the sources of noise of most concern to date have related to commercial transport and whale watching vessels, nearby or potential oil and gas exploration, naval activities such as detonations, the use of harassment devices in aquaculture operations, marine construction, and on-shore detonations. Several kinds of sonar are operated in right whale habitat areas, including both active and passive military sonar, fish-finding sonar, and bottom mapping sonar.
It has been suggested that the constant noise from shipping in the North Atlantic has habituated right whales to ship sounds, making them less likely to avoid oncoming vessels resulting in collisions. It is also argued that right whales have no reason to avoid vessels, since they have no natural predators and these vessels are a recent introduction to their habitat, on the time scale of right whale generations. Nowacek et al. (2004) equipped several right whales with multi-sensor acoustic recording tags to measure the whales' responses to passing ships, and to test the whales' response to controlled sound exposures including recordings of ship noise, right whale social calls, and a signal designed to alert the whales. Nowacek et al. (2004) found that the whales reacted strongly to the alert signal, mildly to the social sounds, but showed no response to the sounds of approaching vessels.
No direct studies have been undertaken in Canadian waters to investigate the effects of non-vessel noise on right whales. Seismic air guns used in petroleum exploration are a source of loud noise that is a potential concern for right whale conservation. In a preliminary study, baleen whales have been observed changing their behaviour in the presence of seismic airgun noise (DFO 2004). Noise from offshore hydrocarbon production platforms and exploration drilling may also be of concern (Richardson et al. 1995), as they generally tend to be of low frequency (<500 Hz). Previous studies have demonstrated avoidance of odontocete species to acoustic harassment devices (e.g. Morton & Symonds 2002), but no data exists on baleen whale responses. Previous studies indicate that blasting for marine construction can lead to damage of ear structures in baleen whales (Ketten et al. 1993).
Vessel presence disturbance
Aside from acoustic disturbance, the presence of vessels - ranging from large commercial ships, to whale watching vessels through small recreational, scientific and fishing boats – in right whale habitat raises several concerns. In addition to noise pollution and the risk of vessel strikes, which have been described earlier, the presence of vessels in important habitat areas may affect right whale behaviour by disturbing social interactions like nursing, or displacing them from rich food patches (e.g. such as has been documented for gray whales, Eschrictius robustus,Bryant et al. 1984).
Changes in food supply
The question of whether right whales in the western North Atlantic are undernourished is closely linked to the quality of their habitat and their ability to use suitable habitat without being seriously disturbed by human activities. This issue was initially addressed by Kenney et al. (1986), who suggested that inadequacy of food resources could lead to either a reduction in individual growth rates, thus lengthening the time required for sexual maturation, or insufficient blubber reserves in females to sustain pregnancy or lactation, resulting in high calf mortality. It is uncertain, at present, whether either of these changes is occurring in the North Atlantic right whale population.
Blubber thickness may be a useful index of body condition in right whales. Scientists who observe right whales in the western North Atlantic regularly see a qualitative difference in the appearance of these whales and Southern Hemisphere right whales, the latter appearing broader bodied and more robust (with a “collar of fat” in the dorsal neck region). An analysis of blubber thickness in North Atlantic right whales compared blubber thickness in different classes with reproductive success (Angell 2005). It showed that blubber thickness and dorsal body shape were indices of right whale energy balance and that the marked fluctuations in reproduction likely have a nutritional component.
Global climate change could be affecting both the local spring and summer distribution of right whales in the Gulf of Maine (Kenney 1998b) and the calving rate of the North Atlantic population (Kenney 1998a).
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 (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 intervals 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 concentration in Roseway Basin was 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 and 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.
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 proposed boundaries of critical habitat to be protected under SARA (Section 58) is provided in Figure 4.
Figure 4: Proposed 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 proposed 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 proposed 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. Roseway Basin is therefore not identified as critical habitat in this recovery strategy. 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 research activities to determine whether Roseway Basin constitutes critical habitat. This will be a high priority Action Plan following completion of the Recovery Strategy, to be completed within 2 years.
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. It is important to note that activities outlined in this schedule are subject to priorities and budgetary constraints of the participating jurisdictions and organizations. Consequently, these activities may not necessarily be completed within the timelines as established below.
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 Roseway Basin Conservation Area as potential critical habitat||Primary||Ongoing||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 whether additional areas of critical habitat exist along the Scotian Shelf||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
Memorial University of Newfoundland
Canadian Whale Institute
Grand Manan Whale and Seabird Research Station
New England Aquarium
National Marine Fisheries Service
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 alter the oceanographic and bathymetric features that lead to prey aggregation or exclude whales from access to critical habitat.
Represents number of catalogued North Atlantic right whales thought to be alive in 2003 (COSEWIC 2003). An accurate population estimate for the species is yet to be calculated, however, Kraus and Rolland (2007) suggest the current population numbers 350 animals.
Institutional affiliation for personal communications can be found at end of the References section.
Unless otherwise specified, where used in document here on in, the term ‘right whale’ will serve as a shortened version of the North Atlantic right whale.
- Date Modified: