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SHORT NOTE
Observations of a distinctive morphotype of killer whale
(Orcinus orca), type D, from subantarctic waters
Robert L. Pitman
•
John W. Durban
•
Michael Greenfelder
•
Christophe Guinet
•
Morton Jorgensen
•
Paula A. Olson
•
Jordi Plana
•
Paul Tixier
•
Jared R. Towers
Received: 17 May 2010 / Revised: 12 July 2010 / Accepted: 14 July 2010 / Published online: 7 August 2010
Ó US Government 2010
Abstract Studies have shown that killer whale (Orcinus
orca) communities in high latitudes regularly comprise
assemblages of sympatric ‘ecotypes’—forms that differ in
morphology, behavior, and prey preferences. Although
they can appear superficially similar, recent genetic evi-
dence suggests that breeding is assortative among ecotypes
within individual communities, and species-level diver-
gences are inferred in some cases. Here, we provide
information on a recently recognized ‘type D’ killer whale
based on photographs of a 1955 mass stranding in New
Zealand and our own six at-sea sightings since 2004. It is
the most distinctive-looking form of killer whale that we
know of, immediately recognizable by its extremely small
white eye patch. Its geographic range appears to be
circumglobal in subantarctic waters between latitudes 40°S
and 60°S. School sizes are relatively large (mean 17.6;
range 9–35; n = 7), and although nothing is known about
the type D diet, it is suspected to include fish because
groups have been photographed around longline vessels
where they reportedly depredate Patagonian toothfish
(Dissostichus eleginoides).
Keywords Killer whale Orcinus orca Subantarctic
Type D
Introduction
Research on killer whales (Orcinus orca) has revealed that,
at least in high latitudes, their communities are often
comprised of different ‘ecotypes’—sympatric, non-inter-
breeding populations that differ in their prey preferences,
social structure, acoustic behaviors, and morphological
traits (Ford et al. 2000; Pitman and Ensor 2003; Foote et al.
2009). Recent genetic evidence suggests that at least some
of these ecotypes represent well-established divergences
and should be considered separate species (LeDuc et al.
2008, Morin et al. 2010).
Three readily field-identifiable killer whale ecotypes
have been described from Antarctic waters (types A, B, and
C; Pitman and Ensor 2003). A fourth and markedly dif-
ferent-looking killer whale from the southern hemisphere
was described by Jefferson et al. (2007); it was referred to
as ‘type D’ and was easily recognizable by its extremely
small white post-ocular eye patch. It seems clear now,
based on comparisons with photographs from recent at-sea
sightings, that this is the same distinctly patterned killer
whale that mass-stranded in Paraparaumu, New Zealand in
1955 (Baker 1983). Here, we provide new information on
R. L. Pitman (&) J. W. Durban P. A. Olson
Protected Resources Division, Southwest Fisheries Science
Center, National Marine Fisheries Service, National Oceanic
and Atmospheric Administration, 8604 La Jolla Shores Drive,
La Jolla, CA 92037, USA
e-mail: robert.pitman@noaa.gov
M. Greenfelder
14940 Elton St. SW, Navarre, OH 44662, USA
C. Guinet P. Tixier
CEBC-CNRS, Villiers-en-Bois, 79360 Beauvoir-sur-Niort,
France
M. Jorgensen
Broagergade 1, 3.th, 1672 København V, Denmark
J. Plana
Quaternary Research Center (CEQUA), Avenida Bulnes 01890,
Casilla 737, Punta Arenas, Chile
J. R. Towers
Marine Education and Research Society, Box 554, Alert Bay,
BC V0N 1A0, Canada
123
Polar Biol (2011) 34:303–306
DOI 10.1007/s00300-010-0871-3
the appearance and distribution of type D killer whale
based on observations and photographs from six recent
at-sea encounters and the 1955 stranding.
Results and discussion
Since 2004, we have recorded at-sea sightings of type D
killer whales from six different locations in the southern
hemisphere. These, along with the New Zealand stranding,
are plotted in Fig. 1; additional details of these encounters
are provided in Table 1, and photographs from each are
shown in Fig. 2.
Its distinctive pigmentation patterning and morphology
make type D killer whale readily identifiable in the field
(Fig. 2). It is a typical black and white form of killer whale,
without the conspicuous dorsal cape of Antarctic types B
and C (Pitman and Ensor 2003). Also, types B and C killer
whales often appear yellow- or brownish-colored due to a
diatom film on their skin (Pitman and Ensor 2003), but
none of the 269 photographs of type D killer whales that
we reviewed showed this condition. The saddle (the light-
pigmented area directly behind and below the dorsal fin) is
moderately conspicuous, unlike killer whales found in the
tropics which typically have faint, often barely discernable
saddles (Baird et al. 2006; Pitman et al. 2007).
The most distinctive feature of type D killer whale is the
extremely small post-ocular white eye patch (Visser and
Ma
¨
kela
¨
inen 2000). As in most killer whale ecotypes, the
eye patch is oriented parallel to the body axis. Noting the
small size of the eye patch from published photographs of
the 1955 stranding, Pitman and Ensor (2003) suggested that
they might have been type C killer whales, but the latter
has a distinctly downward-slanted and somewhat larger eye
patch. Visser and Ma
¨
kela
¨
inen (2000) reported that at least
two of the animals from the 1955 stranding had angled eye
patches, but our large photographic sample of live animals
over a broad geographic range (Fig. 2) shows that the eye
patch is oriented parallel with the body axis. The relative
size of the eye patch in type D is not obviously sex- or age
related because it appears to be of similar relative size in
adult males and females, as well as in calves (Fig. 2).
Type D also has a noticeably bulbous head, so much so
that in at least some individuals the head shape appears
more similar to a pilot whale (Globicephala spp.) than do
other types of killer whales (Fig. 2c, e, g). The dorsal fin is
also distinctive being narrow with a sharply pointed tip and
usually quite backswept (Fig. 2d, f, g). This was especially
Fig. 1 Locations of a stranding
(1) and six at-sea sightings
(2–7) of subantarctic killer
whales (Orcinus orca), type D;
see Table 1 for details
Table 1 Records of type D killer whales from the southern
hemisphere
Record Date Latitude (S) Longitude School size
1 13 May 1955 40°55
0
174°59
0
E17
2
a
24 Nov 2004 53°33
0
42°02
0
W [10
3 26 Dec 2006 52°34
0
2°28
0
E35
4 17 Feb 2009 46°38
0
48°29
0
E9
5 20 Nov 2009 58°39
0
64°32
0
W 15–20
6 12 Dec 2009 51°39
0
169°06
0
E 20–25
7 4 Mar 2010 60°10
0
68°37
0
W 10–15
a
position approximate
304 Polar Biol (2011) 34:303–306
123
evident among adult males (e.g., Fig. 2b, h)—none of the
photos showed the broad-based, erect, triangular dorsal fin
often found among adult males of other ecotypes. There is,
however, marked sexual dimorphism with respect to dorsal
fin size and shape, as in other forms of killer whales.
The plotted locations of the sightings and the stranding
indicate a circumglobal distribution in the southern hemi-
sphere (Fig. 1). Furthermore, the sightings all occurred
between 40°S and 60°S (one was at 60°10
0
S) suggesting a
subantarctic distribution. Although some of the at-sea
sightings were near subantarctic islands (Records 2 and 6,
near Crozet Archipelago and Campbell Island, respec-
tively), the majority were in deep, oceanic water. School
sizes were relatively large, averaging 17.6 animals/school
(range 9–35; n = 7).
At least two types of killer whales are known to occur at
Crozet. A form that looks similar to Antarctic type A
occurs there commonly year-round and appears to have a
generalist diet; it has been observed taking minke whales
(Balaenoptera acutorostrata), southern elephant seals
(Mirounga leonina), and penguins and fish near the islands
(Guinet 1992; Guinet et al. 2000). This is also the form
most commonly involved in the depredation of demersal
longlines targeting Patagonian toothfish (Dissostichus
eleginoides) near Crozet and Kerguelen Islands (Roche
et al. 2007; Tixier et al. 2010). Type D has been recorded
on 14 occasions at Crozet (Tixier unpubl. data) but only in
offshore waters where it also interacts with the toothfish
longliners, suggesting that its diet probably also includes
fish.
Although the at-sea range of type D killer whale likely
overlaps at times with all three of the known Antarctic
ecotypes (Visser 1999; Pitman and Ensor 2003, Tixier
unpubl. data), to date there have been no observed
Fig. 2 Photographs of seven
currently known records of
subantarctic killer whales
(Orcinus orca), type D; the
numbers in parentheses
correspond to individual record
numbers in Fig. 1 and Table 1:
(1) a, stranding in Paraparaumu,
New Zealand, May 1955, photo
courtesy Evening Post
Collection, Alexander Turnbull
Library; (2) b–c, South Georgia,
photos M. Greenfelder; (3) d,
southeast Atlantic, photo P.
Olson; (4) e, Crozet Island,
photo P. Tixier; (5) f, Drake
Passage, photo J. Plana; (6) g,
Campbell Island, New Zealand,
photo M. Jorgensen; (7) h,
Drake Passage, photo A. Scott.
Notice the extremely small
white eye patch of this type,
along with a moderately
conspicuous saddle, lack of a
visible dorsal cape, and rather
bulbous head
Polar Biol (2011) 34:303–306 305
123
interactions among any of them. The one exception that we
are aware of was when a group of type A and a group of
type D were at the same longline fishing vessel at Crozet.
Not only did the two groups not intermingle but they ‘kept
their distance’ (Guinet and Tixier unpublished data). And,
there is no evidence of intergradation with respect to eye
patch size and shape among these forms to suggest
interbreeding.
Variation in the size, shape, and orientation of the
white eye patch of killer whales in the pelagic waters of
the southern hemisphere allows for human observers to
readily distinguish among several different forms and
these same features may also be important for species or
ecotype recognition among killer whales. Based on its
marked morphological divergence and sympatric occur-
rence with other ecotypes of killer whales within its range,
we suggest that type D likely represents yet another
ecotype or possibly even species of killer whale in the
Southern Ocean. Further genetic analyses will be impor-
tant for assessing the phylogenetic status of type D killer
whale. In the meantime, we suggest a more descriptive
common name for this very distinctive morphotype:
‘subantarctic killer whale’.
Acknowledgments We thank Paul Ensor, Nicolas Gasco, Heidi
Krajewsky and Audrey Scott for assistance in the field and Anton van
Helden for providing details about the 1955 stranding. The data for
the 2006 sighting was collected during an International Whaling
Commission minke whale assessment cruise in Antarctica; we thank
IWC for permission to use the data. This manuscript benefited from
the comments of John Ford and an anonymous reviewer.
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