Atlantic White-Beaked Dolphin
Collaborating author: Nicole Vollmer, Smithsonian. VollmerN@si.edu
Family: Delphinidae
Species: Lagenorhynchus albirostris
Length: males up to 3.1 m, females up to about 3.0 m (1-2)
Weight: 180-360 kg (2)
Life expectancy: estimated maximum age for females is 34 years and is unknown for males (2)
Atlantic white-beaked dolphin
Description and Taxonomy: White-beaked dolphins are toothed whales and therefore are odontocetes. They have a very robust body, a prominent, falcate dorsal fin, and a short beak (rostrum) that typically has white pigmentation on it. Large dark regions on the dorsal sides of these dolphins are interrupted by blazes of white and light grey. Like most odontocetes, white-beaked dolphins have rows of sharp, conical teeth along their upper and lower jaws, which they use to catch their prey. The white-beaked dolphin is currently one of six species grouped together within the genus Lagenorhynchus; however, data based on molecular genetics suggests that the six members of this genus are not closely related and should be split up into multiple different genera (e.g., 3, 4). Furthermore, there is some evidence based on skull morphology that two different morphotypes may exist, one in the east and the other in the western North Atlantic (5).
At the population level, there is currently no evidence to support that the Gulf of St. Lawrence harbors a resident, genetically distinct population of white-beaked dolphins, and molecular and morphological studies are ongoing to investigate population structure of this species across the North Atlantic (6-8).
Distribution: The white-beaked dolphin is found in cold temperate and sub-polar waters throughout the North Atlantic and is generally considered to be more northern in distribution compared to the Atlantic white-sided dolphin (Lagenorhynchus acutus). Generally white-beaked dolphins are found along the continental shelf and most typically in waters less than 200m depth. In the eastern Atlantic, they range from France, north to the Barents Sea, across the North Atlantic to Iceland, southern Greenland, central Davis Strait, and in the western Atlantic south to Cape Cod, Massachusetts (9). In the Gulf of St. Lawrence, white-beaked dolphins are most often seen starting in July with sightings trailing off by mid-September. In the Gulf, white-beaks are typically seen less often than Atlantic white-sided dolphins, and in the past 10 years sightings in the interior of the Gulf have been rare (*).
Life History: Females reach sexual maturity around 8-16 years of age, typically around 2.4 m in length, while males are sexually mature around 11-13 years and around 2.7 m in length (1, 2, 10). Gestation is estimated to last on average 11 months and calving typically takes place during summer months. Generally, the white-beaked dolphin is not well-studied and much is still unknown about its life history.
Diet: White-beaked dolphins are known to feed on a variety of both schooling and bottom-dwelling fish (herring, capelin, cod, haddock and whiting), invertebrates (squid and octopus), and benthic crustaceans (2, 10). Differences in diet of white-beaked dolphins are likely attributed to differences in geography and local availability and abundance of prey.
Behavior: White-beaked dolphins are a social species that lives and travels in typically smaller groups of less than 10 animals, but have also been sighted in groups of over 100 animals (10). Along the north shore of the Gulf of St. Lawrence, groups of 10-35 animals have been observed most often (11). White-beaked dolphins often display aerial behaviors such as jumping and bow-riding, and they have also been observed alongside feeding humpback and fin whales, and sometimes with other species of dolphins (10). Since these dolphins are toothed whales, they can use echolocation to find prey in deep murky water. The dolphin emits clicks produced in their sinus cavities and directs them out into the water column through their melon, or forehead, where the sound waves bounce off objects and allow the dolphin to acoustically visualize where its prey is and what kind of fish or invertebrate it is. Unlike the Atlantic white-sided dolphin, white-beaked dolphins do not commonly strand in large numbers, but rather singly or in small groups (10).
Conservation: According to the International Union for Conservation of Nature and Natural Resources (IUCN), the white-beaked dolphin is considered Least Concern (9). However, this species has been incidentally killed from interactions with fishing gear. Furthermore, opportunistic hunts for white-beaked dolphins are known to occur in remote regions of Labrador and the southwest coast of Greenland, and in several instances, white-beaked dolphin mortalities have occurred from ice entrapment off the coast of Newfoundland (2, 12, 13).
References:
(1) Perrin WF, Reilly SB. 1984. Reproductive parameters of dolphins and small whales of the Family Delphinidae. Rep Int Whal Commn Special Issue 6: 97-133.
(2) Kinze CC. 2009. "White-beaked dolphin, Lagenorhynchus albirostris." Encyclopedia of Marine Mammals. 2nd Ed. Perrin WF, Würsig B, Thewissen JGM, eds. Academic Press, Boston: 1255-1258.
(3) LeDuc RG, Perrin WF, Dizon AE. 1999. Phylogenetic relationships among the delphinid cetaceans based on full cytochrome b sequences. Mar Mamm Sci 15: 619-648.
(4) McGowen MR. 2011. Toward the resolution of an explosive radiation - a multilocus phylogeny of oceanic dolphins (Delphinidae). Mol Phylogenet Evol 60: 345-357.
(5) Mikkelsen AMH, Lund A. 1994. Intraspecific variation in the dolphins Lagenorhynchus albirostris and L. acutus (Mammalia: Cetacea) in metrical and non-metrical skull characters, with remarks on occurrence. J Zool Lond 234: 289-299.
(6) Vollmer NL, Gonzalez V, Lesage V, Potter C, Rosel P, Wenzel F. 2015. Detection of fine-scale population structure of the Atlantic white-sided dolphin (Lagenorhynchus acutus) in the western North Atlantic using RAD-seq data. 21st Biennial Conference on the Biology of Marine Mammals, San Francisco, CA.
(7) Banguera-Hinestroza E, Evans PGH, Mirimin L, Reid RJ, Mikkelsen B, Couperus AS, Deaville R, Rogan E, Hoelzel AR. 2014. Phylogeography and population dynamics of the white-sided dolphin (Lagenorhynchus acutus) in the North Atlantic. Conserv Genet 15: 789-802.
(8) Fernández R, Schubert M, Vargas-Velázquez AM, Brownlow A, Víkingsson GA, Siebert U, Jensen LF, Øien N, Wall D, Rogan E, Mikkelsen B, Dabin W, Alfarhan AH, Alquraishi SA, Al-Rasheid KA, Guillot G, Orlando L. 2016. A genomewide catalogue of single nucleotide polymorphisms in white-beaked and Atlantic white-sided dolphins. Mol Ecol Resour 16: 266-276.
(9) Hammond PS, Bearzi G, Bjørge A, Forney K, Karczmarski L, Kasuya T, Perrin WF, Scott MD, Wang JY, Wells RS & Wilson B. 2008. Lagenorhynchus albirostris. The IUCN Red List of Threatened Species 2012: e.T11142A17875454. http://dx.doi.org/10.2305/IUCN.UK.2012.RLTS. T11142A17875454.en. Downloaded on 29 February 2016.
(10) Reeves RR, Smeenk C, Kinze CC, Brownell RR Jr, Lien J. 1998. "White-beaked dolphin Lagenorhynchus albirostris Gray, 1846." Handbook of Marine Mammals. Vol 6. Ridgway S, Harrison R, eds. Academic Press, San Diego: 1-30.
(11) Sears R, Williamson JM. 1982. Distribution and relative abundance of marine mammals along the Quebec lower north shore and its principal river estuaries (Mingan Island to the Strait of Belle Isle) July to October 1982. Report for Hydro-Québec, Vice Présidence Environment. Mingan Island Cetacean Study, East Falmouth, MA, USA and Sept-Iles, Québec, Canada.
(12) Waring GT, Josephson E, Fairfield-Walsh CP, Maze-Foley K, editors. 2007. US Atlantic and Gulf of Mexico marine mammal stock assessments – 2007. NOAA Tech Memo NMFS NE 205; 415 pp.
(13) Lien J, Nelson D, Hai DJ. 2001. Status of the white-beaked dolphin, Lagenorhynchus albirostris, in Canada. Can Fld Nat 115: 118-126.
(*) unpublished data