Right Whale

North Atlantic Right Whale (Eubalaena glacialis)

Right whales are large baleen whales measuring up to 55 feet long, identified by their large heads, prominent callosities (off-white patches of cornified tissue), and lack of a dorsal fin (1). Historically they were found in shallow temperate to subarctic waters worldwide, but today their precise range is uncertain. Once considered members of the same species, the North Atlantic right whale (Eubalaena glacialis), North Pacific right whale (Eubalaena japonica) and southern right whale (Eubalena australis) are now recognized as three genetically distinct species (2). This profile focuses on the North Atlantic right whale. 

North Atlantic right whales were severely depleted by centuries of whaling, and are now the most endangered of the large whale species (3).  The eastern North Atlantic population is thought to be extinct while about 300 individuals inhabit the western North Atlantic (4).  This small population utilizes foraging and nursery grounds in the Gulf of Maine, Bay of Fundy, and Scotian Shelf, and calving grounds off the coast of Georgia and northern Florida.  Right whales are protected internationally by the International Whaling Commission, and in the U.S. under the Endangered Species Act (ESA) and the Marine Mammal Protection Act (MMPA). 

Although the National Marine Fisheries Service (NMFS) considers the small North Atlantic right whale population viable, its recovery and long-term survival hinge on the reduction of anthropogenic (human-related) mortality (5).  At least one third of right whale deaths are thought to result from human activities.  (6 in 4) and under existing conditions, the population will become extinct in less than two centuries (3).  The two greatest threats to the western North Atlantic population are ship strikes and entanglement in fishing gear.  Given the small population size, each additional loss to anthropogenic mortality represents a serious threat to the species’ prospects for recovery.  Preventing the death of just two female right whales per year would enable the population to stabilize (7).  Conservation strategies in the U.S. therefore devote equal attention to reducing the number of ship strikes and minimizing the risk of entanglement. 

Seventy-five percent of eastern North Atlantic right whales now bear scars from encounters with fixed fishing gear, primarily bottom-set gillnets, traps and pots (8,9).  Whales can become entangled in the buoy lines used to mark fixed gear at the surface, as well as in the buoyant groundlines used to connect traps and sections of net (8).  Some are able to free themselves, while others can be disentangled with assistance from rescue organizations.  Although entanglement can lead to death by drowning, these encounters are usually not lethal in the short term.  Instead, the physical injury, infection, and restricted mobility caused by entanglement become more debilitating over time (10).   

Under the Endangered Species Act and the Marine Mammal Protection Act, NMFS is required to develop a Take Reduction Plan to prevent the depletion of “strategic” stocks.  North Atlantic right whales are managed under the Atlantic Large Whale Take Reduction Plan (ALWTRP), which is intended to reduce the likelihood of injury or death caused by entanglement in fishing gear (11).  Fisheries affected by ALWTRP include the Northeast/Mid-Atlantic lobster trap/pot fishery and gillnet fisheries in the Northeast, Mid-Atlantic, and Southeast regions (11).  ALWTRP establishes seasonal area management (SAM) zones used to regulate fishing activity off Cape Cod during the spring and summer, while dynamic area management (DAM) zones can be enacted to protect temporary aggregations (11).   Other strategies for preventing right whale entanglement include gear modification, such as the use of sinking or neutrally buoyant lines and weak links between lines and buoys, and limitations on fishing activity in high-risk areas (8,12).  Identification of the fishing gear involved in entanglements would be of use in developing targeted mitigation strategies (8), but this idea has traditionally met with strong resistance.  The ideal long-term solution to entanglement will be the development of innovative whale-safe fishing gear which eliminates the potential for entanglement altogether (12)

References and additional resources:

1.  NOAA. NMFS. Northern Right Whale (Eubalaena glacialis).  Downloaded 5 February 2008. http://www.nmfs.noaa.gov/pr/species/mammals/cetaceans/rightwhale_northern.htm

2.  Rosenbaum, H.C., R.L. Brownell, Jr., M.W. Brown, C. Schaeff, V. Portway, B.N. White, S. Malik, L.A. Pastene, N.J. Patenaude, C.S. Baker, M. Goto, P.B. Best, P.J. Clapham, P. Hamilton, M. Moore, R. Payne, V. Rowntree, C.T. Tynan, J.L. Bannister, and R. DeSalle. 2000. World-wide genetic differentiation of Eubalaena: questioning the number of right whale species. Molecular Ecology 9: 1793-1802

3.  Caswell, H., M. Fujiwara, and S. Brault. 1999. Declining survival probability threatens the North Atlantic right whale. Proceedings of the National Academy of Sciences of the United States of America 96: 3308-3313

4.  NOAA. NMFS. 2006. Review of the status of the right whales in the North Atlantic and North Pacific Oceans.  Downloaded 6 February 2008. http://www.nmfs.noaa.gov/pr/pdfs/statusreviews/rightwhale2006.pdf

5.  Reeves, R.R., A. J. Read, L. Lowry, S.K. Katona, D.J. Boness. 2007. Report of the North Atlantic Right Whale Program Review. 13-17 March 2006, Woods Hole, Massachusetts. Downloaded 6 February 2008. http://www.mmc.gov/reports/workshop/pdf/rightwhalereport.pdf

6.  Kraus, S.D. 1990. Rates and potential causes of mortality in North Atlantic right whales (Eubalaena glacialis). Marine Mammal Science 6 (4): 278-291

7.  Fujiwara, M. and H. Caswell. 2001. Demography of the endangered North Atlantic right whale. Nature 414: 537-541

8.  Johnson, A., G. Salvador, J. Kenney, J. Robbins, S. Kraus, S. Landry and P. Clapham. 2005. Fishing gear involved in entanglements of right and humpback whales. Marine Mammal Science 21 (4): 635-645

9.  Myers, R.A., S.A. Boudreau, R.D. Kenney, M.J. Moore, A.A. Rosenberg, S.A. Sherrill-Mix, and B. Worm. 2007. Saving endangered whales at no cost. Current Biology 17 (1): R10-R11

10. Knowlton, A.R. and Kraus, S.D. 2001. Mortality and serious injury of northern right whales (Eubalaena glacialis) in the western North Atlantic ocean. Journal of Cetacean Research and Management (Special Issue) 2: 193-208

11. NOAA. NMFS. 2007. Guide to the North Atlantic Large Whale Take Reduction Plan. Downloaded 10 March 2007. http://www.nero.noaa.gov/whaletrp/plan/ALWTRP%20Guide%20DECEMBER%202007_vs3.pdf

12. Kraus, S.D., 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: 561-562