Eubalaena glacialis (Müller, 1776)

Russell A. Mittermeier & Don E. Wilson, 2014, Balaenidae, Handbook of the Mammals of the World – Volume 4 Sea Mammals, Barcelona: Lynx Edicions, pp. 186-215 : 209-210

1.

North Atlantic Right Whale

Eubalaena glacialis

French: Baleine noire / German: Atlantik-Nordkaper / Spanish: Ballena franca del Atlantico

Other common names: Biscayan Right Whale, Black Right Whale, Nordcaper, Northern Right Whale

Taxonomy. Balaena glacialis Müller, 1776 ,

North Cape, Norway.

This species is monotypic.

Distribution. N Atlantic, ranging from feeding areas used from spring to autumn (including Gulf of Maine, Bay of Fundy, and as far N as Nova Scotia) to the latewinter birthing grounds along the SE coast of North America (off Florida and Georgia), as well as sightings in the Gulf of Mexico and off Bermuda to the S; there are occasional records from Greenland, Iceland, and Norway. In the E Atlantic, historical records range S to Cintra Bay (23° N), Western Sahara.

Descriptive notes. Total length 1500-1650 m; weight up to ¢.70,000 kg. As is true of the other species of right whales, the North Atlantic Right Whale is of enormous size. All species in the family Balaenidae are sexually dimorphic, with females growing slightly larger than males. It is generally black. Some individuals may have white areas ventrally on throat and abdominal region. Blubber layer is very thick, ¢.15-20 cm. Stout and stocky, girth of the North Atlantic Right Whale may be greater than 60% of total length. Proportionately large head can be roughly one-third of body length. Blowhole openings, positioned posteriorly on head, are widely separated from one another and angle slightly to the sides, causing spout to form a V-shaped spray 5 m high. Rostrum is narrow, elongate, and markedly arched. There are ¢.200-270 (average 250) thin baleen plates, each ¢.300 cm long. Baleen is gray-brown to black or and is fringed with long, fine, gray bristles. Lower lips form a pronounced arc, closing over baleen on each side of rostrum. Eyes are located just above apex of mouth on either side. Callosities are present on head in patterns that vary among individuals but in generally consistent locations, including behind blowhole, along rostrum, above eyes, on chin, and along mandibles. Hair sometimes grows in areas with callosities. Amphipod crustaceans, “whale lice,” belonging to the family Cyamidae commonly inhabit the callosities and feed on whale skin. Callosities are naturally gray or black but develop a white, yellow, or orange tint depending on the species of whale lice ( Cyamus ovalis , C. gracilis, or C. erraticus) inhabiting them. Male North Atlantic Right Whales generally have proportionally greater areas covered by callosities than females. There is no dorsal fin or ridge on the wide, smooth back. Flippers are relatively large, broad, and paddle-shaped, with angular leading edges. There is a deep notch between wide (up to ¢.30% oftotal body length), gently curving flukes.

Habitat. Temperate waters of coastal regions, including shallow basins, areas over the continental shelf, and deeper areas over the continental slope. Availability of the copepod Calanus finmarchicus is considered an important factor in habitat suitability of North Atlantic Right Whales. Interestingly, although C. finmarchicus is dormant throughout the Gulf of Maine during winter, North Atlantic Right Whales apparently continue to prey on them at great depths in smaller regional basins. Young copepods develop during onset of the seasonal thermocline and the spring phytoplankton bloom into late-stage copepodites and adults by late spring. Data on prey species and oceanographic parameters have been used to model habitat suitability for North Atlantic Right Whales on a weekly timescale in Cape Cod Bay and Great South Channel of the North Atlantic Ocean, and they demonstrated that habitat use patterns change seasonally. Inclusion of prey as a variable was an important factor in model accuracy; presence of C. finmarchicus was most influential to habitat suitability in winter and spring. Such habitat modeling allows prediction of whale presence on a real-time basis and may be important to conservation efforts. During the birthing season in winter, pregnant females are often observed in relatively sheltered, shallow coastal regions in their southern distribution. For pregnant females, presence of prey may be a less important factor in habitat selection than winter oceanographic conditions. As in other mysticete species, there is some evidence of maternal habitat fidelity in North Atlantic Right Whales and indication of learned habitat selection. Offspring learn suitable habitat in the company of their mothers, returning to those habitats in subsequent years.

Food and Feeding. The North Atlantic Right Whale feeds mainly on calanoid copepods, most commonly C. finmarchicus. Documented prey items also include Pseudocalanus spp., Centropages spp., barnacle larvae, juvenile euphausiids, and a variety of nektonic plankton. The North Atlantic Right Whale is a skim feeder, swimming slowly with mouth open through densely concentrated swarms of prey, closing the mouth occasionally to flush out water. Feeding occurs at the water’s surface and, more frequently, deep below the surface. Feeding near the seafloor also apparently occurs occasionally. Generally, whales skimming with their mouths open at the surface, stop, closing their mouths, after having reached the end of a prey patch. Whales feeding at depth breath in c.10-15minute intervals, and thus their mouth-closing actions are more regular. Feeding dives commonly last c.10-20 minutes.

Breeding. Some details of reproduction have been very well documented for the North Atlantic Right Whale, based on long-term studies using photo-identification of individuals. Long-term research over a period of several decades has shown fluctuation in its reproductive rate and birth intervals (time period between successive births for a single female). Birth intervals of North Atlantic Right Whales increased from an average of three years between births during the 1980s to more than five years by the late 1990s. Mean age of female maturity increased from approximately seven to nine years of age during the same period of study, and there was a significant decline in number of offspring produced per mature females during this time (mean percentage of offspring per mature female was 0-25%). In 2000-2005, however, birth rate increased; in previous decades, annual production of offspring for the population averaged twelve individuals annually, but then increased to 31, 29, 19, 16, and 28 offspring/year from 2001 to 2005, respectively. Right whales, in general, are thought to reach sexual maturity at body lengths of 1300-1400 cm. Courtship behavior is observed throughout the year on both birthing and feeding grounds, but fertile breeding is thought to be seasonal, with most births occurring from late December to March, with a peak in early January. Gestation is thought to be ¢.12-13 months, as has been determined for the Southern Right Whale (FE. australis ). A single young is born. Neonates are 400-550 cm long and weigh ¢.800 kg. Observations of live births of North Atlantic Right Whales at sea are extremely rare. Two live births were opportunistically observed and documented during aerial survey work in recent years. Fetal folds may be observed in newborns. Pale gray areas on head and rostrum of newborns where callosities will develop may be apparent but are smooth; they will become thickened during the first few months after birth, perhaps due, at least in part, to habitation by whale lice. Cyamids have not been observed in the callosities of newborns. Duration of lactation is 8-17 months, and it is thought that most young are weaned within their first year. Growth is rapid, with offspring reaching at least ¢.900 cm at weaning. Post-weaning growth may slow markedly until the young whale is of sufficient size and feeding ability to forage efficiently. Maximum age for North Atlantic Right Whales is not known, in part because of the difficulty of developing reliable age-determination methodologies for baleen whales, but photoidentification has placed one individual at a minimum of 70 years of age.

Activity patterns. Right whales, in general, are commonly slow moving and occasionally rest at the surface for long periods. Nevertheless, the North Atlantic Right Whale is frequently observed engaged in active surface behavior, including breaching, lobtailing, flipper slapping, and raising flukes proceeding deep dives. It also has been observed to be very tactile, touching and rubbing conspecifics.

Movements, Home range and Social organization. In the spring, North Atlantic Right Whales, predominately females with newborns and subadults (non-breeding females and most males may remain in northern areas throughout the year), move northward along the east coast of North America from late-winter birthing grounds off Florida and Georgia to late-spring and autumn, near-shore feeding grounds with cooler ocean temperatures and higher biological productivity. These feeding areas include certain basin areas within the Gulf of Maine, Cape Cod Bay, Massachusetts Bay, Great South Channel, lower Bay of Fundy, and as far north as Nova Scotia. By summer and autumn, North Atlantic Right Whales are generally observed in the Bay of Fundy between New Brunswick and Nova Scotia, Canada, and at sites on the continental shelf of Nova Scotia. There may also be feeding grounds farther offshore and to the north. Regional movements between summer feeding grounds may be common and can be far-ranging. Longitudinal photo-identification studies of North Atlantic Right Whales in combination with satellite telemetry data collected from individuals equipped with radio tags in the Bay of Fundy over the last several decades have augmented visual survey data to reveal long-distance excursions. Individual movements from feeding grounds have proven to be highly variable. Some individuals moved extensively around the Gulf of Maine, Nova Scotia Shelf, northern Mid-Atlantic Bight, and the continental slope. Some radio-tagged individuals made trips exceeding 2000 km before returning to feeding grounds in the Bay of Fundy. Pregnant female North Atlantic Right Whales and many subadults leave feeding grounds in late autumn and move southward to warmer birthing grounds. Thus, there is apparent regional segregation during winter, with only part of the population present on birthing grounds. Adult females that are not giving birth have generally not been observed on birthing grounds, and adult males are generally absent. Location of these mature whales is uncertain, and it is also uncertain if this non-birthing segment of the population is aggregated elsewhere or scattered in areas of the North Atlantic Ocean. Results of recent demographic modeling, based on past survey work and comparisons of known individuals from photo-identification catalogues, suggest that significantly higher proportions of both known fathers and known conceptive females were present in whale aggregations in the Gulf of Maine during the winter breeding season compared with most other areas seasonally inhabited by right whales during this period. The work is not conclusive, but it may suggest that regions of the Gulf of Maine (and potentially other northern areas) are a mating ground for North Atlantic Right Whales. Although large aggregations may be observed on birthing and feeding grounds, North Atlantic Right Whales are commonly found alone, in pairs, or in small groups.

Status and Conservation. CITES Appendix I. Classified as Endangered on The IUCN Red List. The North Atlantic Right Whale was found historically on both sides of the Atlantic, and it was considered to have consisted of two populations. The eastern North Atlantic population, which is now functionally extinct,is thought to have ranged from Cintra Bay (c.23° N), a once important winter birthing ground along the coast ofthe Western Sahara to the Bay of Biscay and northward to North Cape, Norway. Population designation for individuals occasionally observed during recent years in Iceland and Norway is undetermined. In the western North Atlantic, the population of the North Atlantic Right Whale was estimated at 490 individuals in 2010. The last assessment of this population for The IUCN Red List classified it as Endangered in 2008 when the population was believed to number only 300-350 individuals along the east coast of North America. Although a roughly 1-6% increase in reproductive rate has been observed in recent years (documented in 2001 and 2005), the increase is not enough to compensate for the estimated 2% annual decline in population size that had occurred over previous decades. No original pre-whaling population estimate is available for North Atlantic Right Whales off North America, but the low estimate for the number killed between 1634 and 1951 is 5500 individuals, and it is possible that twice that number were killed. Major threats to the North Atlantic Right Whale along the east coast of North America today, are ship strikes and bycatch in different types of fishing gear. Between 1970 and 2009, 38 North Atlantic Right Whales were recorded to have been killed in vessel collisions, and 31 were killed from fishery entanglements. These numbers are not sustainable given the small population size of the North Atlantic Right Whale. Examination of photographs of 626 individuals, taken between 1980 and 2009, indicated that c.83% had scars from being entangled in fishing gear at least one time and 59% had marks from having been entangled more than once. Subadults were entangled at a higher rate than adults. Low-frequency noise produced by ships masks naturally occurring sounds and causes habitat displacement, behavioral changes, ad-Justments in vocalizations, and increased levels of physiological stress. Vessel and sonic activity associated with oil and gas exploration are also known to expose large whales to detrimental noise levels. Other threats including low genetic variability, poor nutrition, chemical contaminants, biotoxins, and disease appear to be minor compared with ship strikes and entanglements.

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Figures

1. North Atlantic Right Whale (Eubalaena glacialis), 2. North Pacific Right Whale (Fubalaena japonica), 3. Southern Right Whale (Fubalaena australis), 4. Bowhead Whale (Balaena mysticetus)

Distribution. N Atlantic, ranging from feeding areas used from spring to autumn (including Gulf of Maine, Bay of Fundy, and as far N as Nova Scotia) to the latewinter birthing grounds along the SE coast of North America (off Florida and Georgia), as well as sightings in the Gulf of Mexico and off Bermuda to the S; there are occasional records from Greenland, Iceland, and Norway. In the E Atlantic, historical records range S to Cintra Bay (23° N), Western Sahara.