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Observations of a distinctive morphotype of killer whale (Orcinus orca), type D, from subantarctic waters


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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 evidence suggests that breeding is assortative among ecotypes within individual communities, and species-level divergences 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). KeywordsKiller whale– Orcinus orca –Subantarctic–Type D
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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
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
M. Greenfelder
14940 Elton St. SW, Navarre, OH 44662, USA
C. Guinet P. Tixier
CEBC-CNRS, Villiers-en-Bois, 79360 Beauvoir-sur-Niort,
M. Jorgensen
Broagergade 1,, 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
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
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
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
Record Date Latitude (S) Longitude School size
1 13 May 1955 40°55
24 Nov 2004 53°33
W [10
3 26 Dec 2006 52°34
4 17 Feb 2009 46°38
5 20 Nov 2009 58°39
W 15–20
6 12 Dec 2009 51°39
E 20–25
7 4 Mar 2010 60°10
W 10–15
position approximate
304 Polar Biol (2011) 34:303–306
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
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
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
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
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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... Trois écotypes d'orques ( « Crozet », « type D » et « type C ») ont été documentés autour des archipels de Crozet et Kerguelen (Pitman et al., 2011;Pitman & Ensor, 2003). Les écotypes désignent différentes populations d'orques définies sur la base de différences morphologiques, génétiques, écologiques et enfin comportementales (Ford, 1998;Morin et al., 2010;Pitman et al., 2011;Pitman & Ensor, 2003). ...
... Trois écotypes d'orques ( « Crozet », « type D » et « type C ») ont été documentés autour des archipels de Crozet et Kerguelen (Pitman et al., 2011;Pitman & Ensor, 2003). Les écotypes désignent différentes populations d'orques définies sur la base de différences morphologiques, génétiques, écologiques et enfin comportementales (Ford, 1998;Morin et al., 2010;Pitman et al., 2011;Pitman & Ensor, 2003). Les orques de type Crozet sont généralistes dans leurs préférences alimentaires, avec des proies incluant l'éléphant de mer austral (Mirounga leonina), des manchots (Eudyptes sp.), des poissons et d'autres cétacés. ...
... De plus, cette population d'orque est l'une des rares pratiquant l'échouage volontaire afin de capturer les pinnipèdes (Guinet, 1991). Contrairement aux orques de Crozet, qui sont rencontrées dans les eaux côtières et hauturières, les orques de Type D sont uniquement rencontrées dans les eaux hauturières et leur écologie alimentaire reste méconnue (Jefferson et al., 2007 ;Pitman et al., 2011). Enfin, les orques de type C sont principalement distribuées le long des zones côtières et peuvent être considérées comme spécialistes dans leurs préférences alimentaires principalement composées de poisson Pitman & Ensor, 2003). ...
Les espèces qui se nourrissent de plantes ou d’animaux élevés ou capturés par l’homme, un comportement appelé « déprédation », entraînent souvent de graves Conflits Homme-Faune sauvage (CHF). La déprédation a été signalée dans le monde entier et, dans les écosystèmes marins, elle a été développée par de nombreux grands prédateurs se nourrissant des prises de pêche, ce qui a un impact à la fois sur les activités de pêche et les interactions écologiques. Cependant, bien que les approches écosystémiques soient de plus en plus utilisées dans la gestion des pêches, les effets de la déprédation sur l’ensemble de l’écosystème sont encore rarement considérés de manière holistique. Par conséquent, cette thèse a (i) identifié les limites, manques et priorités pour le développement d’approches de modélisation intégrant la déprédation et (ii) évalué la capacité de deux approches de modélisation existantes pour caractériser les conséquences de la déprédation marine et, plus spécifiquement, comprendre les enjeux et conditions requises pour que les activités d’exploitation halieutique et les déprédateurs marins puissent co-exister. Cette thèse est composée de cinq chapitres. Le chapitre 1 présente le contexte dans lequel s’inscrit ces travaux. Le chapitre 2 identifie les principales lacunes dans les connaissances et met en évidence les principales orientations futures pour parvenir à une inclusion efficace de la déprédation dans les études de modélisation en réalisant une revue systématique. Le chapitre 3 utilise le cadre Ecopath pour évaluer les effets de la déprédation sur l'écosystème dans une étude de cas bien documentée impliquant des mammifères marins et une pêcherie commerciale. Le chapitre 4 s'appuie sur une modélisation qualitative pour évaluer les conditions de persistance d'une ressource exploitée, d'une pêcherie et d'une espèce déprédatrice dans les systèmes marins touchés par la déprédation, et la façon dont la déprédation marine affecte les réponses à long terme à des scénarios alternatifs. Enfin, la discussion générale présentée dans le chapitre 5, fournit des recommandations qui vise à mieux comprendre et prévoir les effets de la déprédation au niveau du socio-écosystème.
... There is a slight margin of identification error since Type D killer whales are smaller than the Crozet type and they have distinctive tiny eyepatches (Pitman et al., 2011;Tixier et al., 2016Tixier et al., , 2014b. All these data were available through the Pecheker database (accessible from the Natural History Museum of Paris; Martin & Pruvost, 2007). ...
... Diet and foraging strategies of Type D killer whales are still poorly understood. However, this ecotype has been described as potential deep divers, suggesting that this ecotype may also feed on benthic prey (Pitman et al., 2011;Tixier et al., 2016). Interactions described between Type D killer whales and toothfish longline fisheries during hauling strongly suggests that this ecotype also naturally feeds on toothfish (Tixier et al., 2016). ...
Odontocetes depredating fish caught on longlines is a serious socio‐economic and conservation issue. A good understanding of the underwater depredation behavior by odontocetes is therefore required. Historically, depredation on demersal longlines has always been assumed to occur during the hauling phase. In this study, we have focused on the depredation behavior of two ecotypes of killer whales, Orcinus orca, (Crozet and Type D) from demersal longlines around the Crozet Archipelago (Southern Indian Ocean) using passive acoustic monitoring. We assessed 74 hr of killer whale acoustic presence out of 1,233 hr of recordings. Data were obtained from 29 hydrophone deployments from five fishing vessels between February and March 2018. We monitored killer whale buzzing activity (i.e., echolocation signals) as a proxy for feeding attempts around soaking longlines. These recordings revealed that the two ecotypes were feeding at close range from soaking longlines, even when fishing vessels were not present. Our results suggest that both killer whale ecotypes are likely to depredate soaking longlines, which would imply an underestimation of their depredation rates. The implication of underestimating depredation rates is inaccurate accounting for fish mortality in fisheries' stock assessments.
... Antarctic ecotypes appear to be sympatric in range and exhibit unique diets, with parallels to the patterns observed in the eastern North Pacific ecotypes (Foote et al., 2019;Pitman & Ensor, 2003;Pitman et al., 2011). For other regions of the Southern Hemisphere, including Australasia, there is little knowledge about killer whale ecotypes and their population structure. ...
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Population genomic data sets have enhanced power to detect cryptic and complex population structure and generate valuable information for the conservation and management of wildlife species. Globally, killer whales (Orcinus orca) are considered to have a complex population structure due to their ability to specialize in a variety of ecological niches. In the Australasian region, they are found year round in New Zealand waters and are sighted in all Australian waters, with seasonal aggregations in the northwest (NWA) and southwest (SWA). Regionally, there is some knowledge regarding killer whale abundance, diet, acoustics, and social structure, but limited information about their population structure. Here, we present a population structure assessment of Australasian killer whales using 17,491 high quality genome‐wide single nucleotide polymorphisms (SNPs), combined with sequences of the mitochondrial DNA control region. The results indicate a minimum of three populations: New Zealand, NWA, and SWA. These populations present moderate levels of genomic diversity, negligible levels of inbreeding, small effective population sizes, and low contemporary migration rates among them. Mitochondrial DNA analysis elucidated five closely related haplotypes, suggestive of matrilineal societies, consistent with killer whales elsewhere. This information will assist conservation management of killer whales in the Australasian region.
... Antarctic Type A killer whales are the largest killer whale ecotype in the Southern Hemisphere, with a reported maximum length of 9.0 m for males and 7.7 m for females (Mikhalev et al., 1981;Pitman & Ensor, 2003;Fearnbach et al., 2019; Figure 1A). This ecotype has shown a preference for ice-free waters, and it exhibits a circumpolar distribution often associated with their preferred prey-Antarctic minke whales (Balaenoptera bonaerensis) in Antarctic waters (Fearnbach et al., 2019), and seals and penguins in Subantarctic waters (Condy et al., 1978;Guinet, 1992;de Bruyn et al., 2013;Travers et al., 2018). ...
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Five ecotypes of killer whales occur in the southern hemisphere: Types A, B (B1 and B2), C, and D. Antarctic Type A has a circumpolar distribution around Antarctica, and are often associated with their preferred prey (minke whales, seals and penguins) in ice-free waters. Ecotype B typically occurs near or within pack ice where they predomi­nantly consume seals, as well as fish, squid, and penguins. Type C killer whales have been predominantly sighted in East Antarctica, and relatively little is known about the Type D individuals. We report seven sightings of Antarctic Type B and C killer whales in Australian coastal waters—as well as a third morphological form, closely resembling the Antarctic Type A ecotype. These records confirm that at least two of the five Antarctic eco-types described from the Southern Hemisphere also occur in Australian coastal waters.
... These killer whales experienced a sharp decline in the late 1990s primarily caused by IUU vessels using lethal measures to prevent depredation interactions; the population currently includes between 89 and 94 individuals (Poncelet et al. 2010, Tixier et al. 2017. To a lesser extent, depredation events involve Type-D killer whales, a genetically distinct form from the Crozet killer whales found in offshore waters only (Pitman et al. 2011. ...
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Fisheries modify prey availability for marine predators by extracting resources but also by providing them with new feeding opportunities. Among these, depredation, which occurs when predators feed on fish caught on fishing gear, is a behavior developed by many species as a way to acquire food through limited foraging effort. However, the extent to which depredated resources from fisheries contribute to the energetic requirements and affect the demography of depredating individuals is unknown. We investigated the contribution of Patagonian toothfish Dissostichus eleginoides depredated on longlines to the energetic requirements of killer whales Orcinus orca around the Crozet Islands (southern Indian Ocean) over the period 2007−2018. Our results indicate that during days when depredation occurred, depredating individuals fulfilled on average 94.1% of their daily energetic requirements with depredated toothfish. However, the contribution varied from 1.2 to 13.3% of the monthly energetic requirements and from 2.4 to 8.8% of the yearly energetic requirements of the total population. Together, these findings suggest that intake of depredated toothfish can be substantial at a fine scale (daily and individually), potentially leading to temporary provisioning effects and changes in predation pressures. These effects become minor (<10%), however, when considering the full population over a whole year. The contribution of depredated fish to the annual energetic requirements of the population has increased in recent years, likely due to larger fishing quotas and greater opportunities for whales to depredate, which stresses the importance of accounting for depredation in ecosystem-based management of fishing activity.
... In addition to the aforementioned specialized structures, caudal keels, a pair or pairs of lateral keel-like structures along the caudal peduncle (as shown in Fig. 1), are remarkable specializations that occur in tuna 2,27 and other thunniform swimmers, e.g., swordfish, 28 lamnid sharks, 8 and cetaceans. 29,30 The caudal keels of tuna were noticed by researchers some decades ago. Gregory 31 hypothesized that the caudal keels produce lift in a morphological study. ...
Tunas are known for their extraordinary swimming performance, which is accomplished through various specializations. The caudal keels, a pair of lateral keel-like structures along the caudal peduncle, are a remarkable specialization in tunas and have convergently arisen in other fast-swimming marine animals. In the present study, the hydrodynamic function of caudal keels in tuna was numerically investigated. A three-dimensional model of yellowfin tuna with caudal keels was constructed based on previous morphological and anatomical studies. Vortical structures and pressure distributions are analyzed to determine the mechanisms of thunniform propulsion. A leading-edge vortex and a trailing-edge vortex are attached to the caudal fin and enhance the thrust. By comparing models of tuna with and without caudal keels, it is demonstrated that caudal keels generate streamwise vortices that result in negative pressure and reduce the transverse force amplitude. Moreover, the orientations of the streamwise vortices induced by caudal keels are opposite to those on the pressure side of the caudal fin. Therefore, caudal keels reduce the negative effects of the streamwise vortices adjacent to the caudal fin and thereby enhance the thrust on the caudal fin. A systematic study of the effects of variations in the Strouhal number (St), the Reynolds number (Re), and the cross-sectional shape of the body on the swimming of tuna is also presented. The effects of caudal keels are magnified as Re and St increase, whereas the cross-sectional shape has no major influence on the caudal keel mechanism.
Although four species of odontocete and four species of baleen whale have been recorded in Prydz Bay, their vocalizations have been rarely investigated. Underwater vocalizations were recorded during March 2017 in Prydz Bay, Antarctica. Bio-duck sounds, downsweeps, inverted “u” shape signals, whistles, pulsed sounds, and broadband clicks were recorded. Bio-duck sounds and downsweeps were associated with Antarctic minke whales (Balaenoptera bonaerensis) based on visual observations. Similarities between inverted “u” shape signals, biphonic calls, and clicks with vocalizations previously described for killer whales (Orcinus orca) lead us believe the presence of Antarctic killer whales. According to sound structures, signal characteristics, and recording location, Antarctic type C killer whales were the most probable candidates to produce these detected calls. These represent the first detection of inverted “u” shape signals in Antarctic waters, and the first report of Antarctic killer whale in Prydz Bay based on passive acoustic monitoring. The co-existence of Antarctic minke and killer whales may imply that minke whales can detect differences between the sounds of mammal-eating and fish-eating killer whales. Our descriptions of these underwater vocalizations contribute to the limited body of information regarding the distribution and acoustic behavior of cetaceans in Prydz Bay.
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The Southern Ocean Research Partnership (IWC-SORP) was established in 2009 with the aim of developing a multi-lateral, non-lethal scientific research programme that would improve the coordinated and cooperative delivery of science to the IWC. There are now 13 member countries in the Partnership: Argentina, Australia, Belgium, Brazil, Chile, France, Germany, Italy, Luxembourg, New Zealand, Norway, South Africa, and the United States. This paper reports on the continued progress of IWC-SORP and its six ongoing research themes1 since the Scientific Committee meeting in 2018. This progress includes the production of at least 18 peer-reviewed scientific papers in 2018/19, bringing the total number of peer-reviewed publications related to IWC-SORP produced since the start of the initiative to ca. 144. Moreover, 133 IWC-SORP related papers have been submitted to the Scientific Committee, 8 of them this year. Fieldtrips to the western Antarctic Peninsula, Marion Island, the Southern Ocean (between 60°S – 67°S and 138°E – 152°E), the Ross Sea and the Great Barrier Reef, Australia have taken place in the past year. Thousands of images for photo-identification have been collected, satellite tags have been deployed on killer whales, Antarctic minke whales and humpback whales. As well as video suction cup tags on Antarctic minke and humpback whales. Biopsy samples have been collected from killer whales, humpback and Antarctic minke whales; and hundreds of hours of cetacean acoustic recordings have been made and analysed. KEYWORDS: SOUTHERN OCEAN RESEARCH PARTNERSHIP, IWC-SORP, ANTARCTICA, ABUNDANCE ESTIMATE, ACOUSTICS, BIOPSY SAMPLING, PHOTO-IDENTIFICATION, SATELLITE TAGGING, MOVEMENT, CONNECTIVITY, RESEARCH VOYAGE
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Interactions between killer whales (Orcinus orca), sperm whales (Physeter macrocephalus), fur seals (Arctocephalus spp.) and longline fishing operations were reported by observers on board fishing vessels targeting Patagonian toothfish (Dissostichus eleginoides) in the Crozet and Kerguelen Islands Exclusive Economic Zones (EEZs) between 2003 and 2005. In the Crozet EEZ, the reported interactions involved killer whales and sperm whales. These two species, alone or in co-occurrence with each other, were observed in 71% of the 1 308 longlines set. In the Kerguelen EEZ, the reported interactions involved sperm whales and fur seals. These two species, alone or in co-occurrence with each other, were observed in 54% of the 6 262 longlines monitored. Interactions were observed in all fishing areas. The effect of depredation was assessed by comparing catch-per-unit-effort (CPUE) (fish weight/hook) of each longline set in the absence/presence of marine mammal species alone or in co-occurrence. In the Crozet EEZ, CPUE was found to be reduced by 22.5% in the presence of killer whales, 12.1% by sperm whales, and 42.5% when both species were present together. An extensive photo-identification effort, primarily focussing on killer whales, allowed a total of 103 individual whales to be identified. The analysis of photo-identification indicated that a small number of individual killer whales were responsible for most of the interactions with the fishery. In the Kerguelen EEZ only sperm whales, alone or in co-occurrence with fur seals, were found to impact negatively on CPUE.
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Within the Crozet Islands Exclusive Economic Zone (EEZ), the Patagonian toothfish (Dissostichus eleginoides) longline fishery is exposed to high levels of depredation by killer (Orcinus orca) and sperm whales (Physeter macrocephalus). From 2003 to 2008, sperm whales alone, killer whales alone, and the two species co-occurring were observed on 32.6%, 18.6% and 23.4% respectively of the 4 289 hauled lines. It was estimated that a total of 571 tonnes (€4.8 million) of Patagonian toothfish were lost due to depredation by killer whales and both killer and sperm whales. Killer whales were found to be responsible for the largest part of this loss (>75%), while sperm whales had a lower impact (>25%). Photo-identification data revealed 35 killer whales belonging to four different pods were involved in 81.3% of the interactions. Significant variations of interaction rates with killer whales were detected between vessels suggesting the influence of operational factors on depredation. When killer whales were absent at the beginning of the line hauling process, short lines (<5 000 m) provided higher yield and were significantly less impacted by depredation than longer lines. Also, when facing depredation, it is recommended that vessels leave their fishing area and travel distances >40 n miles to prevent killer whales from finding them within a few hours. Although more data are still needed to better understand the way killer whales search and detect vessels, this study gives preliminary insights into possible mitigation solutions to the widespread depredation issue.
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Killer whale (Orcinus orca) populations in high latitude, nearshore areas appear to regularly exhibit prey specialisation among two or more sympatric ecotypes, but nearly nothing is known about populations that inhabit open ocean areas or tropical latitudes. On 26 September 2003, during a cetacean survey in the eastern tropical Pacific Ocean, a group of an estimated 19 killer whales was encountered feeding on a calf of a blue whale (Balaenoptera musculus); the location was 10°58’N, 88°40’W, 230km west of Nicaragua. The whales were studied for 2.5 hours and during this time skin biopsy samples were collected, acoustic recordings made, aerial and lateral photographs taken and behavioural observations recorded. The 19 individuals identified included 4 males (3 adults, 1 subadult), 5 cow-calf pairs and 5 other females/subadult males. Using aerial photogrammetry, body lengths of 17 different animals were measured: the largest male (who carried the carcass most of the time) was 8.0m long; and the largest female (with a calf) was 6.1m. From 10 biopsy samples, two distinct haplotypes were identified that differed from resident (i.e. fish-eating ecotype) killer whales in the northeastern Pacific by one and two base pairs, respectively. The single discrete call recorded was a typical killer whale call but it had a two-part pitch contour that was structurally distinct from calls recorded to date in the North Pacific. These observations reaffirm that calves of even the largest whale species are vulnerable to predation, although by migrating to calving areas in the tropics, where killer whale densities are lower, baleen whales should be able to increase their overall reproductive fitness, as suggested by Corkeron and Connor (1999).
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Killer whales around Crozet Islands consume a great variety of preys, including fish, penguins (Eudyptes sp.), elephant seals (Mirounga leonina), and, occasionally, large cetacea. Prédation techniques used on elephant seals and penguins, which are easily observed from the shore, are described. Hydrophones were used to record the acoustic behaviour of the whales during their hunts for both types of prey. The successful predation of 29 elephant seals was observed, 24 of which were weaned pups. Seals were captured along the banks (n = 3), near river outlets (n = 14), by voluntary stranding of the whales on the beaches (n = 7), or by attack of seals swimming in bays (n = 5). Hunting techniques were routinely used in "strategic" points apparently chosen specifically according to the location and climatic factors. King penguins were hunted along the banks (n = 13), particularly where algae prevailed, or offshore (n = 32). While hunting, whales tended to be very quiet and used acoustic signals sparingly, emitting a few isolated clicks and short distance contact calls. Reactions of whales exposed to artificial sounds tended to show that they localize their prey by passive listening. When an elephant seal was captured, long distance contact calls characterized by excitement were emitted 72% of the time and resulted in the arrival, by "porpoising," of the most distant members of the group, along with whales of other groups coming from several kilometers away. The author hypothesizes that the adaptive value of this behaviour is to allow the size of the hunting unit to adjust itself to the size of the prey by permitting not only members of the same groupu to associate, but also members of other groups to associate temporarily.[Journal translation]
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Killer whales (Orcinus orca) have only infrequently been reported from Hawaiian waters, and most of what is known about killer whales worldwide comes from studies in coastal temperate waters. Here we present 21 records of killer whales from within the Hawaiian Exclusive Economic Zone between 1994 and 2004. Killer whales were recorded nine months of the year, most around the main Hawaiian Islands. Although there were more records than expected during the period when humpback whales are abundant around the Islands, there is likely an increase in sighting effort during that period. Killer whales were documented feeding on both a humpback whale and cephalopods, and two species of small cetaceans were observed fleeing from killer whales. Although it is possible that there are both marine mammal–eating and cephalopod-eating populations within Hawaiian waters, it seems more likely that Hawaiian killer whales may not exhibit foraging specializations as documented for coastal temperate populations. Saddle patch pigmentation patterns were generally fainter and narrower than those seen in killer whales from the temperate coastal North Pacific. Analysis of skin samples from two animals indicated two mitochondrial haplotypes, one identical to the “Gulf of Alaska transient 2” haplotype (a mammal-eating form), and the other a new haplotype one base different from haplotypes found for mammal-eating killer whales in coastal Alaskan waters.
I report on a group of orca (Orcinus orca (Linnaeus, 1758)) near the Bay of Islands, New Zealand, which were a lighter coloration than orca usually seen in these waters. Differences in pigmentation included a light grey caudal peduncle area and a dorsal cape, which has previously only been described for Antarctic orca. The size and shape of the eye patches were not consistent with orca photo‐identified in New Zealand. I suggest that this group of orca, although observed in New Zealand waters, were of Antarctic origin.