North Atlantic right whale

Listed: 6/2/1970

Status since listing: Unknown

The northern right whale is composed of two species, the North Atlantic right whale (Eubalaena glacialis) and the North Pacific right whale (Eubalaena japonica) [1]. Both are among the most critically endangered large whales in the world. They were severely depleted by commercial whaling until the 1935 Convention for the Regulation of Whaling [2]. Incidents of illegal whaling continued in the North Pacific through the 1960s, but the whale populations increased significantly over time. However, in the past decade, direct and indirect impacts from human activities have increasingly caused mortalities and may be hindering recovery efforts. Collisions with vessels and entanglement in fishing gear have been particularly problematic, particularly in the North Atlantic. Efforts to protect the northern right whale population increased significantly following completion of the 1991 federal recovery plan.

Western North Atlantic Population
Right whales in the western North Atlantic population range from wintering and calving grounds in coastal waters of the southeastern U.S. to summer feeding and nursery grounds in New England waters and northward to the Bay of Fundy and the Scotian Shelf [2]. New England waters are a primary feeding habitat and serve as a nursery for calves and perhaps also as a mating ground. Known wintering areas for this population are along the southeastern U.S. coast, where calving occurs from December through March and in Cape Cod Bay where they have been sighted from mid January to mid May (although no calving has been confirmed in Cape Cod bay). A majority of the population, however, remains unaccounted for in winter. Recent sightings of known individuals around the Gulf of St. Lawrence, Iceland, and northern Norway as well as in the Gulf of Mexico indicate that ranges may be larger than previously thought and suggest that some important habitat areas have not yet been described [1].

Five areas of "high use" have been identified for western North Atlantic right whales: 1) Coastal Florida and Georgia, 2) The Great South Channel east of Cape Cod, 3) Massachusetts Bay and Cape Cod Bay, 4) The Bay of Fundy, and 5) The Scotian Shelf. The first three of these areas were designated as northern right whale critical habitat in June 1994 [2]. Both Canadian areas were designated as Conservation Zones in the 1990s. Movements within and between these habitats may be extensive. Waters south of Cape Cod and north of the Georgia/Florida winter calving ground, have not been included as "high use" areas, although the coastal waters between the calving and feeding grounds are a well documented seasonal migratory zone.

Estimates of historic population size are not available, although models of population trajectories suggest that there may have been at least several thousand right whales during the early to mid-1600s, with the greatest population decline occurring in the early 1700s [1]. The population may have numbered fewer than 100 individuals by the time international protection for right whales came into effect in 1935. Not enough is known about the population dynamics of right whales during these years, however, to state any estimates with confidence. After 1935, the population is thought to have slowly increased [3] and may have still been increasing at a modest rate (about 2.5%) in the 1980s [2]. More recently, events such as the near-failure of calf production from 1993-95, increased intervals between calving, and a high number of human-induced mortalities, suggest that this modest recovery rate may not have continued in the 1990s. Minimum populations were thought to be 295 in 1992, 263 in 1996, and 291 in 1998. Although calf production has increased recently, the gains from increased birth rates are too small to overcome the estimated population decline of about 2% per year thought to be taking place [4].

Two periods of unusually high mortality have been documented; One from January to March 1996 where five North Atlantic right whale mortalities were reported in waters of the southeastern U.S [1], and one from March 2004 to July 2005 where 8 deaths were reported [4]. Four of the deaths in the latter period were attributable to human activities. Six of the deaths were adult females, 3 of which carried near-term fetuses. The loss of this number of whales, and particularly this number of reproductive females, in such a short period, is unprecedented in 25 years of study. A recent model suggests that, under current conditions, the population is headed for extinction within 191 years [2]. Another model suggests that decreasing mortality of adult females by 2-3 females per year could reverse this negative trend [3].

Ship collisions and fishing gear entanglements are the most common anthropogenic causes of mortality in western North Atlantic right whales [2]. Other potential threats are habitat degradation, noise, contaminants, military activities, climate and ecosystem change. A high proportion of interactions between ships and whales are fatal to the whales -22% of documented deaths between 1970 and 1991 were caused by ship propellers severing the tail stock or spine, or causing mortal wounds on the head. Gear entanglement was estimated to account for 7% of the known mortality between 1970 and 1993. In a recent analysis of the scarification of right whales, a total of 61.6% of the whales bore evidence of entanglements with fishing gear [1]. Further research has indicated that, each year, between 10% and 28% of right whales are involved in entanglements [1]. Although currently no plans to explore or develop oil resources off the coast of the mid and south- Atlantic U.S. have been announced, offshore oil and gas activities have been proposed [2]. If these activities occur, vessel movements, noise, spills, or effluents could result in adverse effects to the right whale population. For waters of the northeastern USA, a present concern not yet completely defined, is the possibility of habitat degradation in Massachusetts and Cape Cod Bays due to a Boston sewage outfall opened in 2000 [1].

Eastern North Atlantic Population
The eastern North Atlantic right whale population may have originally migrated along the coast from northern Europe to the northwest coast of Africa [2]. This population was heavily exploited by whalers during the 14th-16th centuries and again between 1902 and 1920. Since the 1960's, there have only been sporadic sightings of right whales in the eastern North Atlantic. If this population remains extant, little is known about it's distribution and migration. It is considered a 'relict' population that probably numbers only in the low tens of animals and may be functionally extinct.

[1] NOAA Fisheries. 2005. Stock Assessment Report. North Atlantic Right Whale (Eubalaena glacialis): Western Stock revised Dec., 2004. National Oceanic and Atmospheric Administration, Washington, D.C.
[2] National Marine Fisheries Service. 2005. Recovery Plan for the North Atlantic Right Whale (Eubalaena glacialis). Silver Spring, MD. [3] Masami Fujiwara and Hal Caswell. 2001. Demography of the endangered North Atlantic right whale. Nature 414:537-541.
[4] Kraus S., M. W. Brown, H. Caswell, C. W. Clark, M. Fujiwara, P. K. Hamilton, R.D. Kenney, A. R. Knowlton, S. Landry, C. A. Mayo, W. A. McLellan, M.J. Moore, D. P. Nowacek, D. A. Pabst, A. J. Read, and R. M. Rolland. 2005. North Atlantic Right Whales in Crisis. Science 309:5734, pp. 561-562.