Lissodelphis borealis Peale,
English: Northern right-whale dolphin
German: Nördlicher Glattdelphin
Spanish: Delfín liso del norte
French: Dauphin aptère boréal
Lissodelphis borealis © Würtz-Artescienza (see "links")
Right-whale dolphins are easy to identify at sea because of their
distinctive black and white colour and lack of a dorsal fin. The
northern right-whale dolphin is mainly black with a white ventral
patch that runs from the fluke to the throat region. There is a
further small white patch on the tip of the rostrum, and the undersides
of the flippers are also white (Lipsky, 2009). Size reaches ca.
3.1 m in males and 2.3 m in females, and body mass reaches up to
115 kg (Jefferson et al. 2008).
A few individuals possess an alternate colour pattern with a more
extensive white area below. These animals were first referred to
the Southern Hemisphere L.
peronii . Later it was decided that they represented a new
race of the northern species, L. b. albiventris. However,
such individuals occur sporadically in schools of normally-patterned
L. borealis throughout the species' range, and they do not
constitute a taxonomically recognisable population (Rice 1998, and
refs. therein). This is based on Dizon et al. (1994), who found
no evidence of geographically concordant population structuring
by pairwise examination of geographic and genetic distances among
Lissodelphis borealis ranges in temperate and subarctic
waters of the North Pacific, from the Kuril Islands (Russia) south
to the Sanriku coast of Honshu (Japan), thence eastward across the
Pacific between 34° and 47°N, extending north to 55°N,
145°W, in the Gulf of Alaska, to the west coast of North America
from British Columbia, Canada, to northern Baja California, Mexico
(Rice, 1998; Lipsky, 2009).
Distribution of Lissodelphis borealis:
cool, deep temperate waters of the northern
North Pacific (Hammond et al. 2008; © IUCN; Enlarge
Movements beyond the normal range occur occasionally,
as evidenced by sightings as far south as 29°S off Baja California,
Mexico, and as far north as 59°N in the Gulf of Alaska and just
south of the Aleutian Islands in the central Pacific. The northernmost
sightings are generally from summer months and the southernmost
from winter months (Jefferson et al. 1994 and refs. therein; Carwardine,
1995). L. borealis may also occur in the northern Sea of Japan (Carwardine,
3. Population size
Recent abundance estimates for all California, Oregon, and Washington
waters from 1996, 2001, and 2005 surveys were 11,347 (CV = 0.27),
14,937 (0.21), and 11,100 (0.60), respectively (Barlow and Forney
2007 , Forney 2007). Currently, there is no evidence of a trend
in abundance for this stock (Caretta et al. 2008). However, these
values are much lower than peak population size, which was estimated
at 17,800 off southern California, and at around 61,500 off central
and northern California, making them the second or third most abundant
cetacean off California, after Delphinus delphis and Lagenorhynchus
obliquidens (Jefferson et al. 1994). Forney et al. (1995) reported
21,300 animals from Californian waters in winter/spring. Carretta
et al. (2000) counted 754 animals off San Clemente Island during
winter. Buckland et al. (1993) estimated 68,000 in the North Pacific,
and Hiramatsu (1993) estimated the entire population there at 400,000.
However, the latter figure may have been positively biased and there
are no more recent counts available (Hammond et al. 2008).
4. Biology and Behaviour
Behaviour: The animals are easily startled. When fleeing,
a group typically gathers in tight formation, with many animals
leaping simultaneously and often working the sea into a froth. They
may also swim slowly, causing little disturbance of the water and
exposing little of themselves at the surface. Breaching, belly-flopping,
side-slapping, and lobtailing are fairly common. They may bow-ride
but usually avoid boats (Carwardine, 1995).
Habitat: Northern right-whale dolphins are observed most
often in cool, deep, offshore waters over the continental shelf
and beyond, in sea-surface temperatures of 8-9°C. They are sometimes
seen near shore, especially where deep water approaches the coast
(underwater canyons), and apparently prefer "coastal-type"
waters in the California Current system (Jefferson et al. 1994 and
refs. therein; Carwardine, 1995). Ferrero (1998) concluded that
in the central North Pacific sea surface temperature was the most
influential habitat parameter examined, L. borealis occupying
the warmest waters,
P. dalli the coolest, and L.
obliquidens in between. Habitat partitioning was best expressed
by mature female L. borealis, in July, during their calving
period. Mature female L. borealis associated with a consistent
assemblage of other marine organisms during July and August while
associations among other species were more varied.
Schooling: Northern right whale dolphins are highly gregarious.
They are occasionally seen singly but more often in groups of up
to 2,000-3,000. Average herd sizes are about 100 in the eastern
Pacific and 200 or more in the western Pacific (Jefferson et al.
1994 and refs. therein). These groups commonly mix with other marine
mammals, especially Pacific white-sided dolphins, with which they
share a nearly identical range (Jefferson et al. 1993). They also
associate with pilot whales and Risso's dolphins. Travelling speed
may reach 40 km per hour (Lipsky, 2009).
Reproduction: Males become sexually mature at about 9.9
years and females at 9.7 years (Ferrero and Walker, 1993). There
appears to be a calving peak in winter to early spring (Jefferson
et al. 1993). Iwasaki and Kasuya (1997), however, observed a calving
peak between June and August.
Food: Although squid and lanternfish are the major prey
items for right-whale dolphins off southern California, a variety
of surface and mid-water species are taken (Jefferson et al. 1993).
Chou et al. (1995) reported that stomach contents in two L. borealis
consisted of 89% myctophid fish. Other prey species include hake,
saury and mesopelagic fish (Lipsky, 2009 and refs. therein). Ohizumi
and Kato (2004) find that the prey of northern right-whale dolphins
and Pacific white-sided dolphins are closely similar; both feeding
mainly on myctophids in the central North Pacific. Both species
are distributed in the transitional zone, suggesting a potential
competition for food.
Movements south and inshore in winter months and north and offshore
in summer months have been reported for both sides of the Pacific.
Peak periods of abundance off southern California coincide with
peak occurrence there of market squid (Loligo opalescens)
(Jefferson et al. 1994 and refs. therein).
Forney and Barlow (1998) studied seasonal abundance and distribution
of cetaceans within 185-280 km of the California coast during 1991
and 1992. Northern right-whale dolphins were significantly more
abundant in winter than in summer, and significant inshore/offshore
differences were identified. In winter, northern right-whale dolphins
were widespread throughout the continental shelf region of the Southern
California Bight, but no sightings were made there in summer. This
is in agreement with Carretta et al. (2000), who found that off
San Clemente Island, L. borealis were only present between
November and April. During both seasons they were commonly observed
off central and northern California, and in summer they were also
observed off Southern California near the offshore edge of the study
area. This evidence for a winter influx of northern right whale
dolphins into shelf waters of the Southern California Bight in 1991-1992
is consistent with similar findings made during the late 1970s (Barlow,
Direct catch: In the western Pacific, coastal fisheries
off Japan have taken them for many years, with 465 reported killed
in the harpoon fishery in 1949. Although this fishery mainly targets
other small cetaceans, northern right-whale dolphins continue to
be taken (Jefferson et al. 1994 and refs. therein; Lipsky, 2009).
Incidental catch: Northern right-whale dolphin mortality
in the California drift gillnet fishery for broadbill swordfish,
Xiphias gladius, and common thresher shark, Alopias vulpinus,
was estimated at 151 individiuals in 1996 to 2002 (Caretta et al.
2004). However, in recent years, the mortality has dropped drastically
and the average estimate is now 3.8 (CV=0.83) taken annually in
commercial fisheries in eastern US Pacific waters (Caretta et al.
L. borealis has experienced very high levels of fishery-induced
mortality in international high-seas, large-scale driftnet fisheries,
from about 38°N to 46°N, and 171°E to 151°W. Assessing
the impact of this mortality is difficult, however, because of the
possible existence of a coastal population off California and the
Pacific Northwest that is separate from offshore populations (Dizon
et al. 1994). Northern right-whale dolphins have also been observed
entangled in net debris in the western Pacific (Jefferson et al.
1994 and refs. therein).
Total numbers killed by the North Pacific squid driftnet fleets
of Japan, Taiwan, and South Korea in the late 1980s were estimated
at about 15,000-24,000 per year, and this mortality is considered
to have depleted the population to 24-73% of its pre-exploitation
size (Mangel, 1993). This order of magnitude was confirmed by Ferrero
et al. (2002), who reported on having analysed biological specimens
collected by observers monitoring Japanese squid driftnet fishing
operations, consisting of 805 northern right-whale dolphins incidentally
taken in 800 observed gillnet sets.
The UN moratorium on large-scale high-seas driftnets that came
into effect in 1993 is likely to have relieved this pressure to
a considerable extent, but the continued use of driftnets to catch
billfish, sharks, squid, and tuna inside the exclusive economic
zones (EEZ) of North Pacific countries presents an ongoing threat.
Furthermore, continued illegal fishing on the high-seas results
in the killing of unknown numbers of northern right-whale dolphins
each year (Hammond et al. 2008). This is especially concerning,
as catches of driftnets are highly aggregated. Reporting a kill
rate of a fraction of an animal per unit of effort assumes that
driftnets "cull" the population of animals and masks the
more important effect of large, simultaneous kills of large fractions
of pods, families, or other reproductive units. In addition, aggregated
catches may lead to underestimates of the necessary level of observer
effort (Mangel, 1993).
Pollution: The effects of habitat degradation and pollution
on right-whale dolphins are largely unknown, but their pelagic habitat
is probably safer from contaminant effects than coastal areas are.
The seasonal shoreward movements of right whale dolphins may put
them at increased risk during certain times of the year (Jefferson
et al. 1994; Lipsky, 2009). For example, Minh et al. (2000) found
concentrations of polychlorinated biphenyls (PCBs) in one individual
which exceeded levels leading to immunosuppression in harbour seals.
Range states (Hammond et al. 2008):
Canada; Japan; Mexico; Russian Federation; United States of America.
L. borealis is categorized by the IUCN as "Least Concern"
(Hammond et al. 2008). However, the enormous variability associated
with the estimates of population size create difficulties for "statistically
sound analysis" of management plans, as called for by the U.N.
resolutions. In addition, depletion caused by high-seas driftnet
fisheries could even be greater than the worst-case estimate (Mangel,
The species is not listed by CMS. However, south-north as well as
inshore-offshore movements have been reported from both sides of
the Pacific, so Lissodelphis borealis seems to be a good candidate
for inclusion in App. II of CMS. The species is listed in Appendix
II of CITES.
· Barlow J (1995) The abundance of cetaceans
in California waters: Part I. Ship surveys in summer and fall of
1991. Fish Bull, US 93: 1-14.
· Barlow J, Forney KA (2007) Abundance and population density
of cetaceans in the California Current ecosystem. Fish Bull, US
· Buckland ST, Cattanach KL, Hobbs RC (1993) Abundance estimates
of Pacific white-sided dolphin, northern right whale dolphin, Dall's
porpoise and northern fur seal in the North Pacific, 1987-1990.
Biology, distribution and stock assessment of species caught in
the high seas driftnet fisheries in the North Pacific Ocean; 1 Driftnet
fisheries of the North Pacific Ocean; 2 Oceanography biology ecology
all species; 3 Catch and fishery impact all sp, pp. 387-407.
· Carretta JV, Lowry MS, Stinchcomb CE, Lynn MS, Cosgrove
R (2000) Distribution and abundance of marine mammals at San Clemente
Island and surrounding waters: results from aerial and ground surveys
in 1998 and 1999. Admin Rep Southwest Fish Sci Cent 2, 44 pp.
· Carretta JV, Price T, Petersen D, Read R (2004) Estimates
of marine mammal, sea turtle, and seabird mortality in the California
drift gillnet fishery for swordfish and thresher shark, 1996-2002.
Mar Fish Rev 66: 21-30
· Carretta JV, Forney KA, Lowry MS, Barlow J, Baker J, Johnston
D, Hanson B, Muto MM, Lynch D, Carswell L (2008) US Pacific marine
mammal stock assessments 2008. NOAA Techn Mem NMFS SWFSC 434, 340
· Carwardine M (1995) Whales, dolphins and porpoises. Dorling
Kindersley, London, UK, 257 pp.
· Chou L S, Bright AM, Yeh SY (1995) Stomach contents of
dolphins (Delphinus delphis andi Lssodelphis borealis)
from North Pacific Ocean. Zool Stud 34: 206-210.
· Dizon AE, Leduc CA, Leduc RG (1994) Intraspecific structure
of the northern right whale dolphin (Lissodelphis borealis):
The power of an analysis of molecular variation for differentiating
genetic stocks. Rep CalCofi 35: 61-67.
· Ferrero RC (1998) Life history and multivariate analyses
of habitat selection patterns among small cetaceans in the central
North Pacific Ocean. Dissertation Abstracts International Part B:
Science and Engineering 59, no. 3.
· Ferrero RC, Hobbs RC, Van Blaricom GR (2002) Indications
of habitat use patterns among small cetaceans in the Central North
Pacific based on fisheries observer data. J Cetacean Res Manage
· Ferrero RC, Walker WA (1993) Growth and reproduction of
the northern right whale dolphin Lissodelphis borealis, in
the offshore waters of the North Pacific Ocean. Can J Zool 71: 2335-2344
· Forney KA (2007) Preliminary estimates of cetacean abundance
along the U.S. west coast and within four National Marine Sanctuaries
during 2005. U.S. Department of Commerce, NOAA Tech Mem NMFS-SWFSC-406.
· Forney KA, Barlow J, Carretta JV (1995) The abundance of
cetaceans in California waters: Part II. Aerial surveys in winter
and spring of 1991 and 1992. Fish Bull, US 93: 15-26.
· Forney KA, Barlow J (1998) Seasonal patterns in the abundance
and distribution of California Cetaceans, 1991-1992. Mar Mamm Sci
· Hammond PS, Bearzi G, Bjørge A, Forney K, Karczmarski
L, Kasuya T, Perrin WF, Scott MD, Wang JY, Wells RS, Wilson B (2008)
Lissodelphis borealis. In: IUCN 2009. IUCN Red List of Threatened
Species. Version 2009.2. <www.iucnredlist.org>.
· Hiramatsu K (1993) Estimation of population abundance of
northern right whale dolphins in the North Pacific using the bycatch
data from the Japanese squid driftnet fishery. Biology, distribution
and stock assessment of species caught in the high seas driftnet
fisheries in the North Pacific Ocean; 1 Driftnet fisheries of the
North Pacific Ocean; 2 Oceanography biology ecology all species;
3 Catch and fishery impact all sp, pp. 381-386.
· Iwasaki T, Kasuya T (1997) Life history and catch bias
of Pacific white-sided (Lagenorhynchus obliquidens) and northern
right whale dolphins (Lissodelphis borealis) incidentally
taken by the Japanese high seas squid driftnet fishery. Rep Int
Whal Commn 47: 683-692.
· Jefferson TA, Leatherwood S, Webber MA (1993) FAO Species
identification guide. Marine mammals of the world. UNEP/FAO, Rome,
· Jefferson TA, Newcomer MW, Leatherwood S, van Waerebeek
K (1994) Right wale dolphins - Lissodelphis borealis (Peale,
1848) and Lissodelphis peronii (Lacépède, 1804).
In: Handbook of marine mammals (Ridgway SH, Harrison SR, eds.) Vol.
5: The first book of dolphins. Academic Press, London, pp. 335-362.
· Jefferson TA, Webber MA, Pitman RL (2008) Marine mammals
of the world. Elsevier, Amsterdam, 573 pp.
· Lipsky JD (2009) Right whale dolphins - Lissodelphis
borealis and L. peronii. In: Encyclopedia of marine mammals,
2nd Ed. (Perrin WF, Würsig B, Thewissen JGM, eds.) Academic
Press, Amsterdam, pp. 958-962.
· Mangel M (1993) Effects of high-seas driftnet fisheries
on the northern right whale dolphin Lissodelphis borealis.
Ecol App 3: 221-229.
· Minh TB, Nakata H, Watanabe M, Tanabe S, Miyazaki N, Jefferson
TA, Prudente M, Subramanian A (2000) Isomer-Specific Accumulation
and Toxic Assessment of Polychlorinated Biphenyls, Including Coplanar
Congeners, in Cetaceans from the North Pacific and Asian Coastal
Waters. Arch environ Contam Toxicol 39: 398-410.
· Ohizumi H, Kato H (2004) Food of toothed whales in the
northern North Pacific: Geographic and temporal variation. PICES
13th Annual Meeting Book of Abstracts. p. 261
· Rice DW (1998) Marine mammals of the world: systematics
and distribution. Society for Marine Mammalogy, Special Publication
4, Lawrence, KS. USA.
© Boris Culik (2010) Odontocetes.
The toothed whales: "Lissodelphis borealis". UNEP/CMS
Secretariat, Bonn, Germany. http://www.cms.int/reports/small_cetaceans/index.htm
© Illustrations by Maurizio Würtz, Artescienza.
© Maps by IUCN.