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Past and present distribution, densities and movements of blue whales in the Southern Hemisphere and adjacent waters

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Blue whale locations in the Southern Hemisphere and northern Indian Ocean were obtained from catches (303,239), sightings (4,383 records of ≥8,058 whales), strandings (103), Discovery marks (2,191) and recoveries (95), and acoustic recordings. 2. Sighting surveys included 7,480,450 km of effort plus 14,676 days with unmeasured effort. 3. Groups usually consisted of solitary whales (65.2%) or pairs (24.6%); larger feeding aggregations of unassociated individuals were only rarely observed. 4. Sighting rates (groups per 1,000 km from many platform types) varied by four orders of magnitude and were lowest in the waters of Brazil, South Africa, the eastern tropical Pacific, Antarctica and South Georgia; higher in the Subantarctic and Peru; and highest around Indonesia, Sri Lanka, Chile, southern Australia and south of Madagascar. 5. Blue whales avoid the oligotrophic central gyres of the Indian, Pacific, and Atlantic Oceans, but are more common where phytoplankton densities are high, and where there are dynamic oceanographic processes like upwelling and frontal meandering. 6. Compared to historical catches, the Antarctic ("true") subspecies is exceedingly rare and usually concentrated closer to the summer pack ice. In summer they are found throughout the Antarctic; in winter they migrate to southern Africa (although recent sightings there are rare) and to other northerly locations (based on acoustics), although some overwinter in the Antarctic. 7. Pygmy blue whales are found around the Indian Ocean and from southern Australia to New Zealand. At least four groupings are evident: northern Indian Ocean, from Madagascar to the Subantarctic, Indonesia to western and southern Australia, and from New Zealand northwards to the equator. Sighting rates are typically much higher than for Antarctic blue whales. 8. South-east Pacific blue whales have a discrete distribution and high sighting rates compared to the Antarctic. Further work is needed to clarify their subspecific status given their distinctive genetics, acoustics, and length frequencies. 9. Antarctic blue whales numbered 1,700 (95% Bayesian interval 860-2,900) in 1996 (less than 1% of original levels), but are increasing at 7.3% per annum (95% Bayesian interval 1.4-11.6%). The status of other populations in the Southern Hemisphere and northern Indian Ocean is unknown because few abundance estimates are available, but higher recent sighting rates suggest that they are less depleted than Antarctic blue whales.
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Past and present distribution, densities and movements of blue
whales Balaenoptera musculus in the Southern Hemisphere and
northern Indian Ocean
T. A. BRANCH*, K. M. STAFFORD, D. M. PALACIOS, C. ALLISON,
J. L. BANNISTER, C. L. K. BURTON, E. CABRERA, C. A. CARLSON,
B. GALLETTI VERNAZZANI, P. C. GILL, R. HUCKE-GAETE,
K. C. S. JENNER, M.-N. M. JENNER, K. MATSUOKA,
Y. A. MIKHALEV, T. MIYASHITA, M. G. MORRICE, S. NISHIWAKI,
V. J. STURROCK, D. TORMOSOV, R. C. ANDERSON, A. N. BAKER,
P. B. BEST, P. BORSA, R. L. BROWNELL JR, S. CHILDERHOUSE,
K. P. FINDLAY, T. GERRODETTE, A. D. ILANGAKOON,
M. JOERGENSEN, B. KAHN, D. K. LJUNGBLAD, B. MAUGHAN,
R. D. MCCAULEY, S. MCKAY, T. F. NORRIS, OMAN WHALE AND
DOLPHIN RESEARCH GROUP, S. RANKIN, F. SAMARAN,
D. THIELE, K. VAN WAEREBEEK and R. M. WARNEKE
ABSTRACT
1. Blue whale locations in the Southern Hemisphere and northern Indian Ocean were
obtained from catches (303 239), sightings (4383 records of !8058 whales), strandings (103),
Discovery marks (2191) and recoveries (95), and acoustic recordings.
2. Sighting surveys included 7 480 450 km of effort plus 14 676 days with unmeasured effort.
Groups usually consisted of solitary whales (65.2%) or pairs (24.6%); larger feeding aggre-
gations of unassociated individuals were only rarely observed. Sighting rates (groups per
1000 km from many platform types) varied by four orders of magnitude and were lowest in
the waters of Brazil, South Africa, the eastern tropical Pacific, Antarctica and South Georgia;
higher in the Subantarctic and Peru; and highest around Indonesia, Sri Lanka, Chile,
southern Australia and south of Madagascar.
3. Blue whales avoid the oligotrophic central gyres of the Indian, Pacific and Atlantic
Oceans, but are more common where phytoplankton densities are high, and where there are
dynamic oceanographic processes like upwelling and frontal meandering.
4. Compared with historical catches, the Antarctic (‘true’) subspecies is exceedingly rare and
usually concentrated closer to the summer pack ice. In summer they are found throughout the
Antarctic; in winter they migrate to southern Africa (although recent sightings there are rare)
and to other northerly locations (based on acoustics), although some overwinter in the
Antarctic.
5. Pygmy blue whales are found around the Indian Ocean and from southern Australia to
New Zealand. At least four groupings are evident: northern Indian Ocean, from Madagascar
to the Subantarctic, Indonesia to western and southern Australia, and from New Zealand
northwards to the equator. Sighting rates are typically much higher than for Antarctic blue
whales.
*Present address and correspondence: T. A. Branch, School of Aquatic and Fishery Sciences, Box 355020,
University of Washington, Seattle, WA 98195, USA. E-mail: tbranch@gmail.com
Affiliations for all authors are listed in Appendix I.
Mammal Rev. 2007, Volume 37, No. 2, 116–175. Printed in Singapore.
© 2007 The Authors. Journal compilation © 2007 Mammal Society, Mammal Review,37, 116–175
6. South-east Pacific blue whales have a discrete distribution and high sighting rates com-
pared with the Antarctic. Further work is needed to clarify their subspecific status given their
distinctive genetics, acoustics and length frequencies.
7. Antarctic blue whales numbered 1700 (95% Bayesian interval 860–2900) in 1996 (less than
1% of original levels), but are increasing at 7.3% per annum (95% Bayesian interval 1.4–
11.6%). The status of other populations in the Southern Hemisphere and northern Indian
Ocean is unknown because few abundance estimates are available, but higher recent sighting
rates suggest that they are less depleted than Antarctic blue whales.
Keywords: Antarctic blue whales, Balaenoptera musculus brevicauda,Balaenoptera musculus
indica,Balaenoptera musculus intermedia, distribution, pygmy blue whales, true blue whales,
whaling
Mammal Review (2007), 37, 116–175
doi: 10.1111/j.1365-2907.2007.00106.x
INTRODUCTION
The blue whale Balaenoptera musculus is the largest of the mysticete (baleen) whales, with
lengths exceeding 30 m. It was once abundant in the Southern Hemisphere, but was subject
to intensive exploitation by whaling beginning in 1904 (Branch, Matsuoka & Miyashita,
2004); this was particularly true in the Antarctic, where blue whales congregated in summer
to feed, primarily on krill Euphausia superba.
Despite being the largest animals ever to exist on Earth, surprisingly little is known about
the distribution and migration of blue whales in the Southern Hemisphere and northern
Indian Ocean. In this region, there are two recognized subspecies, the Antarctic (or true) blue
whale B. m. intermedia and the pygmy blue whale B. m. brevicauda (Rice, 1998). Compared
with pygmy blue whales, Antarctic blue whales attain greater maximum lengths (>30 m vs.
24.1 m), are longer at sexual maturity (23.7 m vs. 19.2 m) and have proportionately longer
tail regions (Mackintosh & Wheeler, 1929; Ichihara, 1966). In the austral summer, Antarctic
blue whales are generally found south of 55°S while pygmy blue whales are generally believed
to remain north of 54°S (Ichihara, 1966; Kato, Miyashita & Shimada, 1995). Based on a
combination of evidence from three long-term sightings series, Antarctic blue whales were
depleted to very low levels before increasing to 1700 (95% Bayesian interval 860–2900) in
1996, but remain at less than 1% of their original abundance of 239 000 (95% Bayesian
interval 202 000–311 000) (Branch et al., 2004). The status of pygmy blue whales is much
more uncertain but their original abundance was probably an order of magnitude lower than
that of Antarctic blue whales, and they are likely less depleted at present.
The distribution of blue whales in the Southern Hemisphere and northern Indian Ocean is
poorly understood, except perhaps for the Antarctic during the austral summer. Some previous
studies have assumed that they are distributed throughout this region (e.g. Gambell, 1979;
Mizroch, Rice & Breiwick, 1984), presuming that gaps in their distribution are caused by lack
of search and catch effort rather than a true absence of blue whales. However, data from
Japanese Scouting Vessels (JSV, 1965–87) show that despite widespread effort, sightings were
concentrated in the South Indian Ocean and largely absent from the South Pacific and South
Atlantic Oceans (Miyashita, Kato & Kasuya, 1995). Plots interpolated from catches (Mikha-
lev, 2000; Best et al., 2003) are revealing but ignore information from sightings, strandings and
acoustic detections. The best effort at drawing together data from different sources is that of
Yochem & Leatherwood (1985), but their map did not include subsequent revelations of
widespread illegal Soviet catches in the 1960s and 1970s (Yablokov, 1994; Mikhalev, 1997a;
Distribution of southern blue whales 117
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Yablokov et al., 1998); it also interpolated between rare catches in some regions, and contained
many question marks over the distribution of blue whales in other areas.
The classic theory of migration patterns for blue whales may also be in need of revision. It
has long been assumed that Antarctic blue whales migrate to temperate mating and calving
areas in the winter and then return to the Antarctic to feed in the summer. Early work by
Mackintosh & Wheeler (1929) showed conclusively that the whales caught at South Georgia
and at Saldanha Bay, South Africa, were morphologically similar, and that the timing of
catches at the two locations was consistent with migration. Year-round voyages of the
Discovery II showed a marked rise and fall of baleen whale numbers in the Antarctic also
consistent with migration (Mackintosh, 1966). Finally, there is unequivocal evidence for this
migration pattern in humpback whales Megaptera novaeangliae and some indications of a
similar migration in fin whales Balaenoptera physalus; thus, it has been argued by analogy
that the pattern holds also for blue whales (Mackintosh & Wheeler, 1929; Mackintosh, 1966).
More recent analyses of length frequencies (based on a database containing 82% of all
catches between 1914 and 1973) have reinforced the conclusion that Antarctic blue whales
migrate to South African and Namibian waters in winter (Best, 1998; Branch et al., 2007).
Additionally, acoustic recordings (from the 1990s onwards) have detected brief periods of
Antarctic-type calls in the austral autumn and winter (peaking in July) in the eastern tropical
Pacific and central Indian Ocean, and off south-west Australia and northern New Zealand
(Stafford et al., 2004; McDonald, 2006).
However, not all evidence supports the migration hypothesis: some Antarctic blue whales
remain behind during the winter. At South Georgia, blue whales were present year-round
(Hinton, 1915; Risting, 1928). There were also year-round acoustic detections of blue whales
in the West Antarctic Peninsula (Širovic´ et al., 2004) and East Antarctic (McKay, Širovic´ &
Thiele, 2005), although these were greatly reduced in winter.
It is also well-known that pygmy blue whales do not generally migrate to the Antarctic in
summer. Pygmy blue whales in the northern Indian Ocean form a resident population
(Yochem & Leatherwood, 1985; Mikhalev, 2000; Anderson, 2005), and the abundance of
pygmy blue whales around Australia (Gill, 2002), south of Madagascar (Best et al., 2003) and
in the southern Indian Ocean (Zemsky & Sazhinov, 1982; Miyashita et al., 1995) peaks in the
summer months. Blue whale catches and sightings in the south-east Pacific are also more com-
mon in summer than in winter (Clarke, Aguayo & Basulto, 1978; Hucke-Gaete et al., 2003).
To provide updated maps of blue whale distribution, to address questions about the
classical migration theory for blue whales and to compare densities in different regions, we
compiled available data for catches, sightings, strandings, acoustic recordings and Discovery
mark recoveries from a variety of published and unpublished sources. The resulting data were
compared with maps of bathymetry, thermal fronts and phytoplankton biomass to better
understand their association with blue whale distribution. Finally, the whale data were
examined for monthly patterns suggesting migration.
METHODS
The study area is defined to be the entire Southern Hemisphere in addition to the northern
Indian Ocean, because this covers the known distribution of Antarctic and pygmy blue whales.
In the eastern tropical Pacific, sightings between the equator and 5°N are also included,
because extensive surveys there (e.g. Reilly & Thayer, 1990) show that there is a gap (~3–7°N)
between blue whale sightings near the Costa Rica Dome that are from the California/Mexico
population (Mate, Lagerquist & Calambokidis, 1999), and those closer to the equator that
probably come from the south-east Pacific population. Data were collected on bathymetry,
118 T. A. Branch et al.
© 2007 The Authors. Journal compilation © 2007 Mammal Society, Mammal Review,37, 116–175
thermal fronts and phytoplankton biomass to relate these environmental factors to blue whale
distribution. The study focused on positional information from catches, sightings, strandings,
mark-recaptures (using Discovery marks) and acoustic detections, but did not include data
from several satellite tagging and photo-identification studies since these had not yet been
published. Positional data were separated into whaling ("1973) and post-whaling (>1973) eras
to assess whether the occurrence and distribution of blue whales was affected by whaling.
Historical catches
Catch positions were provided by the International Whaling Commission (IWC) Secretariat
and include an up-to-date account of catches by the USSR in the 1950s to 1970s, correcting
for USSR misreporting and illegal whaling (Yablokov, 1994; Mikhalev, 1997a; Yablokov
et al., 1998). Catch positions were recorded to the nearest degree for many earlier catches, but
to the nearest minute for later catches. The positions associated with land station catches were
usually fixed and did not represent the actual catch positions, except in later years. Finally,
the catch database does not have a fully comprehensive set of individual positions, especially
for the early part of the 20th century and during World Wars I and II.
Nearly all whaling on blue whales was conducted in the Antarctic, providing little infor-
mation on blue whale distribution outside this area. However, Soviet vessels travelled widely
outside the Antarctic during the 1950s to 1973, catching whales without regard to closed
seasons, closed areas and forbidden species. Revised data on their catches are available from
1958 to 1973. For this period of time, a proxy of Soviet effort was obtained by comparing the
catches of blue whales with those of all whales for each ¥ square.
Sightings
Sightings were obtained from a wide variety of published papers, technical reports and
unpublished IWC Scientific Committee documents, in addition to unpublished data from the
authors of this paper and other sources listed in the acknowledgements (Appendix 2). Potential
sources were restricted to a manageable number by including only sources that listed blue
whale sightings. Because effort associated with surveys with zero sightings was excluded, total
estimated effort is negatively biased. Where the number of groups of whales was recorded, this
may have referred to schools (stable groups of whales that usually travel together and are often
related) or to feeding aggregations (unstable groups aggregating around an ephemeral food
source). Where later papers referred to the same sightings obtained from another more primary
source, the earlier source was preferred. Less effort was expended in collating sightings prior to
1973 while catches were still being taken. For example, no effort was made to extract data from
logbooks of 19th century American whaling boats except for those collated by Wray & Martin
(1983). Four particularly extensive datasets are described in more detail below.
IDCR/SOWER database
Antarctic surveys were conducted under the auspices of the IWC from 1978/79 to 2005/06,
under the auspices of the International Decade of Cetacean Research (IDCR), and Southern
Ocean Whale and Ecosystem Research (SOWER) programmes (Branch & Butterworth,
2001a; Matsuoka et al., 2003). Sightings were obtained from the IWC’s database DESS 3.42
(Database-Estimation Software System, Strindberg & Burt, 2004) for 1978/79–2004/05.
Details from each survey can be obtained from the individual cruise reports (e.g. Ensor et al.,
1999, 2000, 2004). At the time of submission, sightings had not been encoded from the
2005/06 survey (33 groups, 63 whales) (Ensor et al., 2006).
Distribution of southern blue whales 119
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JARPA database
The Japanese Whale Research Program under Special Permit in the Antarctic (JARPA)
has so far operated from 1989/90 to 2005/06. Blue whale abundance estimates have been
calculated up to the 2004/05 season (Matsuoka et al., 2006), and sightings from 1989/90 to
2004/05 are included in this paper. Effort was widespread south of 60°S and from 35°E
eastwards to 145°W. Additional effort was recorded in much of the region north of 60°S
during transits and during surveys between 57°S and 60°S.
JSV database
Japanese Scouting Vessels (JSV) recorded noon-day positions, total blue whales sighted on
that day, and daily search effort from 1965/66 to 1988/89 (Miyashita, Shigemune & Kato,
1994; Miyashita et al., 1995). However, from the 1978/79 season onwards, some of these
vessels were also used in the IDCR/SOWER surveys, resulting in potential record duplication
in the two databases. Since the IDCR/SOWER records contained more accurate positions
these were preferred, reducing JSV records from 2520 blue whales (recorded on 833 vessel-
days) to 2410 whales (799 vessel-days). JSV recorded the number of groups and number of
whales in most years, but in some years the number of groups was not recorded.
SWFSC surveys in the eastern tropical Pacific
The Southwest Fisheries Science Center (SWFSC) of the U.S. National Marine Fisheries
Service conducted a series of marine mammal surveys in the eastern tropical Pacific between
1986 and 2006 (e.g. Holt & Sexton, 1987; Hill, Rasmussen & Gerrodette, 1991; Mangels &
Gerrodette, 1994; Kinzey et al., 2001; Jackson et al., 2004). The surveys extended eastwards
from Hawaii to California and Mexico and southwards to about 15°S. Previous blue whale
sightings around the Costa Rica Dome (Wade & Friedrichsen, 1979; Reilly & Thayer, 1990)
have been linked through satellite tagging to the Mexico/California population of northern
blue whales, B. m. musculus (Mate et al., 1999). For this reason, only the effort and sightings
south of 5°N were included in this study, as these sightings were considered more likely to be
from the south-east Pacific grouping of blue whales.
Effort assessment
Where reported, the effort associated with each survey was recorded. Where multiple surveys
were conducted in a study, the total effort for all surveys was reported even if blue whales
were not sighted on many individual surveys. However, the effort associated with a very large
number of studies that reported zero blue whale sightings was excluded. Effort was reported
in a variety of ways: days, hours, kilometres or nautical miles. The total effort was estimated
by assuming that 10 hours of effort equalled 1 day and by converting measurements from
nautical miles to kilometres. For sighting rates, where the number of groups was not consis-
tently recorded (e.g. JSV), the number of whales was converted to number of groups using the
mean group size from all other records.
Strandings
‘Strandings’ included both live strandings and washed up and floating carcasses. Sources
(listed in Appendix 3) included published and unpublished reports, and relied heavily upon
previous collations of sightings, e.g. James & Soundararajan (1979), De Silva (1987) and
Sathasivam (2000). Identification was usually clear, as evidenced by a published description
by a cetacean expert, a maximum length exceeding that of other species in the region,
completely black baleen plates or other diagnostic features. Reports identified as B. indica
120 T. A. Branch et al.
© 2007 The Authors. Journal compilation © 2007 Mammal Society, Mammal Review,37, 116–175
(originating from Blyth, 1859) (the Great Indian Fin Whale or Great Indian Rorqual) were
considered to be a synonym for B. musculus (Rice, 1998). Although care was taken to
include only strandings verified to be blue whales, in many cases, particularly in the
northern Indian Ocean, the published descriptions did not provide full details of how the
species identification was made. Original records of older strandings could not always be
obtained as they were often published in obscure and inaccessible journals. In such cases,
the closest summary in time was used and the oldest known reference noted. The reliability
of length measurements varies. Older records probably measured maximum total length
which is appreciably longer than the accepted standard catch measurement from the ‘tip of
the snout to the notch of the tail flukes’ (Mackintosh & Wheeler, 1929); thus, older mea-
surements are probably biased high. In the majority of cases, the name of the stranding
location was given but not the exact latitude and longitude. In these cases, the place was
located using Google Earth software (http://www.earth.google.com) to find the most accu-
rate position. This was particularly difficult for Indian place names where variant spellings
and name changes were common.
Mark-recaptures and movements
The only source of mark-recapture data included in this paper are Discovery marks, but a
brief outline of known work on photo-identification and satellite tags is summarized at the
end of this section.
Mark and recapture data from the Discovery marking program and the International
Marking Scheme were obtained from the IWC Secretariat and are listed in Appendix 4.
Marks consisted of a metal tube stamped with a unique serial number that was fired into
the muscle of the whales, and recovered during whaling (Brown, 1954, 1962). The mark-
recaptures included three (no. 25601, no. 25608, no. 25619) from Soviet expeditions
(Mikhalev & Tormosov, 1997) not currently in the IWC database, and excluded German
mark G00706, which had a missing recapture location. There is some doubt about the
mark positions and species identity (fin or blue whale) of Soviet marks no. 1294 and no. 1298
reported in Ivashin (1971); thus, these were excluded. There were nine instances where two
marks were recaptured from a single whale. In each instance, both marks had been placed on
the same day and almost identical location; thus, the numerically higher mark was excluded
from analyses of the Discovery marks.
Photo-identification studies include those from Sri Lanka (Alling, Dorsey & Gordon,
1991), and studies in progress in Perth Canyon in Western Australia (K. C. S. Jenner,
M.-N. M. Jenner & V. J. Sturrock, unpublished data), Bonney Upwelling, southern Aus-
tralia (P. C. Gill & M. G. Morrice, unpublished data), Geographe Bay, Western Australia
(C. Burton, unpublished data), Chile (Hucke-Gaete, Viddi & Bello, 2005; Cabrera et al.,
2006), Indonesia (B. Kahn, unpublished data) and the Southern Ocean (P. Olson, personal
communication).
Satellite tagging has been conducted around Australia (N. Gales, K. C. S. Jenner & P. C.
Gill, unpublished data), Indonesia (Kahn, 2005) and Chile (Hucke-Gaete et al., 2005).
Acoustic detections
Acoustic recordings of Southern Hemisphere blue whales were obtained from a variety of
sources based on bottom-moored or sound channel-moored hydrophones, dipping hydro-
phones and sonobuoys (Appendix 5). Sonobuoys record data over relatively short time
frames (hours), whereas moored hydrophones are capable of collecting year-round
datasets. Sonobuoys were deployed during seven SOWER cruises (1996–2006) both in the
Distribution of southern blue whales 121
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Antarctic and in pygmy blue whale habitat during the austral summer. The distance at
which calls can be detected depends on many factors including bottom topography type,
ambient noise levels, instrument type, and depth of the vocalizing whale and receiver. Since
these factors were seldom recorded in our sources, it is generally not possible to estimate
how far away the calling whales were. Širovic´ (2006) does estimate that Antarctic-type calls
from the Antarctic Peninsula were detected up to 200 km away from bottom-mounted
instruments in October and November, but we believe the distance to be much less for
most of the other studies cited.
Reliability of data
The catch database covers 83.6% of known catches of blue whales in the study area. Similarly,
the set of mark-recaptures examined is comprehensive and differs little from previous exten-
sive analyses (Rayner, 1940; Brown, 1954, 1962). Strandings are more commonly reported
from areas of high human population density and where there are cetacean experts, which
explains why strandings were reported in such high numbers from India, Sri Lanka, Austra-
lia, New Zealand and Chile. The absence of any strandings around Africa, despite high
catches from the south-west coast, is at least partly due to low monitoring effort. The
sightings data were often from surveys in restricted areas, except for major efforts like JSV,
JARPA and IDCR/SOWER. Many areas were never surveyed while other areas were inten-
sively studied. Since sighting effort was not included from publications recording zero blue
whales, the study-wide sighting rate estimate will be biased high. Finally, sighting rates are
obviously difficult to compare from one study to another because the sighting platform,
number of observers, vessel speed, sighting conditions and many other factors vary. Never-
theless, blue whales produce highly visible and relatively frequent blows so that we assumed
that sighting rates varying by an order of magnitude or more would reflect real differences in
densities. Acoustic data provide reliable presence-absence information but were often
obtained incidental to other studies and did not include concurrent visual sightings of blue
whales. Although relative densities can be inferred from the number of calls recorded, it is
unknown what proportion of blue whales produces calls and therefore acoustic data cannot
be used to estimate the number of individuals in range of the acoustic instrument.
Bathymetry, thermal fronts and phytoplankton chlorophyll-a concentrations
To better understand the possible environmental correlates of blue whale distribution, large-
scale positions of bathymetry, thermal fronts and phytoplankton biomass were obtained
from digital sources. Bathymetry for the study area was obtained from version 8.2 (Novem-
ber 2000) of the dataset described in Smith & Sandwell (1997), and was downloaded from the
website of the Institute of Geophysics and Planetary Physics, Scripps Institution of Ocean-
ography (http://topex.ucsc.edu/). These data come from a combination of depth soundings
and satellite gravity measurements and have a nominal resolution of about 4 km.
Following the representation of Moore & Abbott (2000), we obtained the mean annual
position of the major fronts in the Southern Ocean. These include, from north to south: the
North Subtropical Front, the Agulhas Current Front, the South Subtropical Front, the
Subantarctic Front, the Southern Antarctic Circumpolar Current Front, and the Antarctic
Polar Front. For the more northern regions, we considered the annual mean location of the
Costa Rica Dome in the eastern tropical Pacific (~9°N 90°W), as outlined by the 20°C
isotherm depth at 35 m (Fiedler, 2002), and the location of the 25°C isotherm at the surface,
which marks the position of the seasonal Equatorial Front in the eastern equatorial Pacific
and eastern equatorial Atlantic. The surface manifestation of the 25°C isotherm also
122 T. A. Branch et al.
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describes the extent of south-west monsoon-induced upwelling in the western Indian Ocean.
The mean position of the 25°C isotherm was obtained from a satellite-derived sea-surface
temperature climatology for the month of August from NOAA’s National Oceanographic
Data Center (http://www.nodc.noaa.gov/sog/pathfinder4km/) (sensor: AVHRR, grid resolu-
tion: 4 km, base period: 1985–2001; see Casey & Cornillon (1999) for details of an earlier
version of this product).
Long-term annual and seasonal mean phytoplankton chlorophyll-a concentrations, a
proxy for biomass, were obtained in mg.m-3from satellite measurements (sensor: SeaWiFS,
grid resolution: 9 km, base period: 4 September 1997 to 30 September 2006; http://
oceancolor.gsfc.nasa.gov/). One caveat is that these measurements are from surface waters
and may not reflect phytoplankton biomass associated with the deep chlorophyll maximum.
RESULTS
Catches
The IWC catch database includes catch positions for 303 329 blue whales (and individual
data for 311 948 whales in all) in the study area, i.e. 83.6% of the estimated 362 879 blue
whales caught in this region (Branch et al., 2004). Figure 1 shows the distribution of the catch
and the major environmental features of the study area, although treatment of the association
between the latter and blue whale distribution is left for the Discussion section. Catches
covered the Antarctic densely. The major concentrations of catches in the Antarctic shifted
southwards from October–December to January–March (Fig. 2). In the South Pacific, there
were widespread catches along the west coast of South America north of 44°S off Chile, Peru
and Ecuador and from Peru to the Galapagos Islands, but no other catches north of 59°S in
the waters stretching west to 180°. In the South Atlantic, there were isolated catches off
Argentina, Uruguay and Brazil. However, the identification of one of the two Brazilian
catches is questionable given that it was recorded as either a ‘bowhead or blue’ whale, neither
of which is very likely. There were substantial catches off Angola, Namibia and the west coast
of South Africa and a single catch off Congo. Catches were common off Durban (South
Africa), from south of Madagascar to Australia, around the south and west coasts of
mainland Australia and Tasmania, in the north-western Indian Ocean, and north-west of
New Zealand. Pelagic catches in the Indian Ocean were limited to the 1959/60–1963/64
Japanese expeditions and 1962/63–1972/73 USSR expeditions capitalizing on the discovery of
pygmy blue whales (Ichihara, 1961).
The pattern of Soviet catches (1958–73) of all large cetacean species is revealing (Fig. 3). In
some areas, Soviet blue whale catches were very scarce despite considerable catches of other
large cetaceans, particularly in the South Atlantic, central Indian Ocean, south of South
America and in the Tasman Sea.
Sightings
The sightings database included 4383 records comprising at least 8058 individual whales
(Appendix 2), of which 3691 records of at least 6019 whales were recorded after 1973.
Sightings largely mirrored the catch distribution, except for scattered sightings in the South
Pacific and South Atlantic, broad areas south and south-west of Australia, in Indonesia and
north of New Zealand to the equator (Fig. 4). In the Antarctic, all sightings were clustered
close to the continent in a much more restricted range than the catches. Where individual
group sizes were recorded (n=3346; mean =1.56; S.E. =0.026; range =1–60), the great
majority comprised one (65.2%) or two whales (24.6%), and groups exceeding five whales
were rare (1.1%) (Table 1). The total estimated effort where recorded was ~14 676 days (624
Distribution of southern blue whales 123
© 2007 The Authors. Journal compilation © 2007 Mammal Society, Mammal Review,37, 116–175
groups) plus ~7 480 450 km (3365 groups). Overall sighting rates were therefore approxi-
mately 0.04 per day or 0.45 per 1000 km (one group every 2200 km), but are obviously biased
upwards because most studies focused on high-density blue whale areas and many studies
that reported no blue whales were excluded. For large-scale surveys with dedicated cetacean
effort and good sighting platforms, sighting rates varied by more than four orders of mag-
Fig. 1. (a) Bathymetry and mean location of major oceanographic features in the study area (see text for
details). From north to south: CRD, Costa Rica Dome; EF, Equatorial Front; NSTF, North Subtropical
Front; AgCF, Agulhas Current Front; SSTF, South Subtropical Front; SAF, Subantarctic Front; APF,
Antarctic Polar Front; SACCF, Southern Antarctic Circumpolar Current Front. (b) Annual mean
phytoplankton chlorophyll-aconcentrations in mg.m-3from SeaWiFS (4 September 1997–30 September
2006). (c) Catches of blue whales in the International Whaling Commission database grouped into ¥
squares. Catches from land stations were generally all assigned to the same square.
124 T. A. Branch et al.
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Fig. 2. Three-monthly seasonal patterns in catches (grouped into ¥ squares) and mean seasonal phytoplankton chlorophyll-aconcentrations in mg.m-3. Sources are the
same as Fig. 1.
Distribution of southern blue whales 125
© 2007 The Authors. Journal compilation © 2007 Mammal Society, Mammal Review,37, 116–175
0
1
24
519
2099
100
80°S
60°S
40°S
20°S
20°N
180°W 120°W 60°W 60°E 120°E 180°
80°S
60°S
40°S
20°S
20°N
0
0.02
0.1
0.2
0.5
1
180°W 120°W 60°W 60°E 120°E 180°
80°S
60°S
40°S
20°S
20°N
80°S
60°S
40°S
20°S
20°N
Fig. 3. Soviet catches during 1958–73 in the study area. Top panel: number of catches of all large cetaceans in each ¥ square (a rough measure of total catch effort).
Bottom panel: proportion of large cetacean catches in each ¥ square that were blue whales.
126 T. A. Branch et al.
© 2007 The Authors. Journal compilation © 2007 Mammal Society, Mammal Review,37, 116–175
nitude from region to region. When ordered, these sighting rates (groups per 1000 km) are as
follows: off Costinha, Brazil, 0.003 (da Rocha, 1983); off Durban, South Africa, 0.005 from
spotter planes (P. B. Best, unpublished data); around Somalia, 0.19 (Small & Small, 1991);
around the Galapagos Islands, 0.25 (Palacios, 1999a); Oman, 0.32 (Oman Whale and
Dolphin Group, unpublished data); Antarctica south of 55°S, 0.17 (JSV), 0.34 (JARPA,
Matsuoka et al., 2006) and 0.52 (IDCR/SOWER); South Georgia, 0.44 (Moore et al., 1999);
in the eastern tropical Pacific, 0.45 (SWFSC surveys); off Peru, 0.73 (Donovan, 1984a) and
0.97 (Valdivia et al., 1983; Ramirez, 1985); around Komodo and Solor-Alor, Indonesia, 2.0
(Kahn, 2000, 2002, 2005; B. Kahn, unpublished data); Maldives, 2.4 (Ballance et al., 2001);
southern Indian Ocean 35–50°S 30–100°E, 2.9 (JSV); east Sri Lanka, ~6 assuming vessel
speed of 5 knots (Alling et al., 1991) and north-west Sri Lanka, 1.6 (A. D. Ilangakoon,
Fig. 4. Positional information from (top to bottom) sightings (!); strandings ("); and acoustic recordings
(#). Grey is used for positions "1973 and black for >1973. Acoustic locations are annotated with the call
type using numbers: Antarctic (1), South-east Pacific (2), New Zealand (3), Sri Lanka (4), Australia (5) and
Madagascar (6); these numbers are concatenated if two or more call types were recorded at a single
location.
Distribution of southern blue whales 127
© 2007 The Authors. Journal compilation © 2007 Mammal Society, Mammal Review,37, 116–175
unpublished data); off southern Australia, 7.4 (Gill, 2002; P. C. Gill & M. G. Morrice,
unpublished data); off western Australia, 18.5 (K. C. S. Jenner, M.-N. M. Jenner & V. J.
Sturrock, unpublished data) and 18.6 (J. L. Bannister & C. L. K. Burton, unpublished data);
on the Madagascar Plateau, 36.0 (Best et al., 2003); and off Chile, 4.9 from a ship survey
(Findlay et al., 1998) and 52.4 from aerial surveys north-west of Chiloé Island (Galletti
Vernazzani, Carlson & Cabrera, 2005; Galletti Vernazzani et al., 2006).
Nearly all of the sightings on the IDCR/SOWER surveys were near the southern boundary
of the survey region despite substantial effort northwards of the pack ice to 60°S (Fig. 5).
Furthermore, during transits to the Antarctic, sightings were recorded only in the southern
Indian Ocean, and never during transits south of South Africa, South America, Tasmania, or
New Zealand despite substantial search effort.
The JSV database included 4 827 370 km of search effort throughout the study region
(Fig. 6), but sightings per 1000 km varied dramatically from region to region. The highest
sighting rates were recorded between 40°S and 55°S in the southern Indian Ocean and south
of Australia. Dramatically lower sighting rates were recorded in the South Atlantic, central
Indian Ocean, Tasman Sea and southern Pacific Ocean. In the Antarctic, blue whales were
generally recorded only in a few of the most southern ¥ squares.
Sightings from the SWFSC surveys in the eastern tropical Pacific were grouped into those
off Mexico, those on or near the Costa Rica Dome and those near to or south of the equator
(Fig. 7). Only sightings from the last grouping were analysed further in this paper.
Table 1. Distribution of group sizes
in sightings data, based on reports
where group sizes were recorded.
Groups may have been either
schools or feeding aggregations,
depending on the source. The
largest groups were 10, 12, 15, 18,
20 and 60.
Group size Frequency Percentage
1 2183 65.2
2 822 24.6
3 205 6.1
4 62 1.9
5 37 1.1
6 15 0.4
7 6 0.2
8 6 0.2
9 4 0.1
!10 6 0.2
Total 3346 100.0
Fig. 5. IDCR/SOWER vessel tracks (lines) and blue whale sightings (!) between 1978 and 2005. Only
primary search effort is plotted, but blue whales sighted both on-effort and off-effort are plotted. The
intended surveys were generally conducted south of 60°S (dashed line) but additional primary effort was
recorded further north during transits to the survey areas. IDCR, International Decade of Cetacean
Research; SOWER, Southern Ocean Whale and Ecosystem Research.
128 T. A. Branch et al.
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1199 km
200499
500999
10004999
>= 5000
180° 120°W 60°W 60°E 120°E 180°
80°S
60°S
40°S
20°S
80°S
60°S
40°S
20°S
0 per 1000 km
0.010.99
11.99
22.99
34.99
>= 5
180° 120°W 60°W 60°E 120°E 180°
80°S
60°S
40°S
20°S
80°S
60°S
40°S
20°S
Fig. 6. Japanese Scouting Vessels (JSV) effort in km (top panel), and sightings per unit effort (bottom panel) in each ¥ sector in the Southern Hemisphere. The JSV
database covers the period from 1965 to 1987 but does not include effort and sightings for the northern Indian Ocean.
Distribution of southern blue whales 129
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Strandings
We found records of 103 strandings in the study area (Appendix 3). Most of the strandings
were reported from the south-east Pacific, in the northern Indian Ocean (Pakistan, India, Sri
Lanka, Bangladesh, the Maldives), on the south and south-west coasts of Australia, and in
north-west New Zealand (Fig. 4). Isolated strandings were also reported from Uruguay, New
Caledonia, northern Australia and Indonesia, but none were reported from any African
country. All strandings were of solitary individuals, although a notable stranding on 23
January 1946 in Trincomalee Harbour, Sri Lanka, was of a pregnant female that gave birth
in the harbour the following day and was then towed to safety (Deraniyagala, 1948).
Reported lengths ranged from 6.35 m to 29.3 m but most blue whales measured in recent
times (after 1927) were shorter than the maximum pygmy blue whale length of 24.1 m
(Ichihara, 1966), except for a 27.4 m whale reported at Orewa, New Zealand in 1978 (A. N.
Baker unpublished data). In addition, bones from a 24.0 m blue whale stranded near Bus-
selton, Western Australia & in 1898 reveal that it was a physically immature Antarctic blue
whale (Bannister, Burton & Hedley, 2005), and the skeleton still exists of a properly measured
26.5 m blue whale stranded on 8 February 1908 north of Okarito, New Zealand (Waite, 1912;
Stollman et al., 2005).
Mark-recaptures
There were 104 Discovery marks recovered from 95 individual whales (Appendix 4) and an
additional 2191 Discovery marks that were not recovered (Fig. 8). Some blue whales were
caught far from the mark position, but there was no obvious increase in the distance between
marks and recoveries with increased time except that recoveries in the same season were
usually closer to the mark position than recoveries after one season or more (Figs 8 and 9).
160°W 150°W 140°W 130°W 120°W 110°W 100°W 90°W 80°W
160°W 150°W 140°W 130°W 120°W 110°W 100°W 90°W 80°W
20°S
10°S
10°N
20°N
30°N
20°S
10°S
10°N
20°N
30°N
Fig. 7. Southwest Fisheries Science Center surveys between 1986 and 2006 in the eastern tropical Pacific.
Grey lines indicate primary search effort, while circles show both on-effort and off-effort sightings of blue
whales. Only sightings and effort south of 5°N were included in the analyses presented in this paper.
130 T. A. Branch et al.
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Most marked blue whales (n=54) were caught in the same season, but 15 were caught more
than two seasons later and one evaded capture for 13 years 10 months and 12 days. With one
exception, mark-recapture pairs were all south of 53°55S and between October and March
and can be presumed to be Antarctic blue whales. The single exception was a blue whale
marked at 56°15S 49°03E on 1 December 1962 that was identified as a pygmy blue whale
when caught at 43°55S 50°02E on 4 April 1963 (Ichihara, 1966).
Acoustics
Acoustic recordings were distributed widely around the Antarctic, around the Indian Ocean,
off northern New Zealand and in the south-east Pacific (Fig. 4). The earliest Southern
Hemisphere acoustic recordings in the presence of blue whales were off Chile in 1970 (Cum-
mings & Thompson, 1971). They described long (10–30 seconds), low-frequency (10–40 Hz),
multi-unit sounds; all subsequent recordings of blue whales share these characteristics, but
are also geographically distinct both within and between ocean basins. Distinct call types
have been described in the literature associated with the following regions: the Antarctic,
Fig. 8. Discovery mark placement (triangles, top panel) and recoveries of Discovery marks (arrows, other
panels) of blue whales. The top panel shows the positions of all marks (grey "1973, black >1973), panels
below zoom into a narrower latitudinal range to show all mark-recaptures. Mark-recapture pairs are split
between those recovered in the same season, the following season, two seasons later and more than two
seasons after the mark. The shortest mark-recapture path sometimes crosses the international dateline. Only
the same-season recovery at 43°55S 50°02E was identified as a pygmy blue whale.
Distribution of southern blue whales 131
© 2007 The Authors. Journal compilation © 2007 Mammal Society, Mammal Review,37, 116–175
south-east Pacific, Madagascar, Australia, Sri Lanka and off northern New Zealand (e.g.
Stafford, Nieukirk & Fox, 1999; McCauley et al., 2001; Stafford et al., 2004; McDonald,
2006; reviewed by McDonald, Hildebrand & Mesnick, 2006).
In all Antarctic regions, a unique call type sometimes referred to as the ‘28-Hz pulse’ or
‘28-Hz tone’ has been recorded together with the low-frequency downsweeps common to blue
whales worldwide (Fig. 4) (Ljungblad, Clark & Shimada, 1998; Stafford et al., 1999; Clark &
Fowler, 2001; Širovic´ et al., 2004; Stafford et al., 2004; McKay et al., 2005; Rankin et al.,
2005; Ensor et al., 2006). This 28-Hz tone is now considered diagnostic of the Antarctic
subspecies (Rankin et al., 2005) and has been recorded from sonobuoys on SOWER cruises
(December–February) coincident with blue whale sightings or at night when blue whales had
been seen during the day (Ljungblad et al., 1998; Clark & Fowler, 2001; Rankin et al., 2005;
Ensor et al., 2006). Short recordings of Antarctic-type calls were also recorded 4–6 April 2004
near South Georgia (C. W. Clark & A. R. Martin, personal communication) which represents
the furthest north they have been recorded in the Atlantic Ocean.
The seasonal occurrence of Antarctic blue whale calls can be obtained from moored
instruments. Distinctive 28-Hz tones were recorded on instruments moored to the west and
north of the Antarctic Peninsula in all months with strong seasonal peaks in February–May
and October–November, and low numbers of calls during June–August during high ice
concentration cover (Širovic´ et al., 2004). These 28-Hz tones were also recorded year-round
from an instrument moored at 66°44S 69°48E with peaks in April–June, October–
November and a dearth of calls in December–March, although this analysis is preliminary
(McKay et al., 2005). Additionally, there are limited records of 28-Hz tones in mid and low
latitudes during May to September in the Pacific and Indian Oceans, suggesting that at least
0
4
8
12
16
Same season
0
4One season
0
4Two seasons
0
4More than two seasons
180 120 60 30 0 30 60 90 120 150 180
Movement (degrees longitude)
Frequency
Fig. 9. Longitudinal movement between marks and recoveries of blue whales in the same season, after
1 year, 2 years and more than 2 years. Positive numbers indicate eastward movement and negative numbers
westward movement.
132 T. A. Branch et al.
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some Antarctic blue whales migrate northwards in the austral winter (McCauley et al., 2004;
Stafford et al., 2004; McDonald, 2006). In the eastern tropical Pacific, these calls were
recorded in low numbers from May to September, with peak number of calls in July at 8°S
95°W and 8°S 110°W (Stafford et al., 1999). Near northern New Zealand (36°22S 175°54E),
28-Hz tones were recorded in May to July (McDonald, 2006). Off south-western Australia
(~34°54S 114°06W) they were recorded from May to November (peak in July) (McCauley
et al., 2004; Stafford et al., 2005), and near Diego Garcia (~7°S 72°E) from May–August 2002
(peak in July) (Stafford et al., 2004). Finally, 28-Hz tones were recorded near Crozet Island
at 46°10S 51°48E but no seasonal information was provided (Samaran et al., 2006).
None of the other five blue whale call types have been recorded in the Antarctic south of
60°S. These other call types have usually been labelled as ‘pygmy’ blue whales and differ
according to ocean basin. Three distinct call types have been recorded from the Indian Ocean
(Alling et al., 1991; Ljungblad et al., 1998; McCauley et al., 2001), one from the south-east
Pacific (Cummings & Thompson, 1971; Stafford et al., 1999), and one likely pygmy blue
whale call type from the south-west Pacific (Kibblewhite, Denham & Barnes, 1967;
McDonald, 2006), but no pygmy-type call has yet been recorded from the Atlantic Ocean.
The first of the three distinct Indian Ocean call types was recorded in the presence of blue
whales off north-east Sri Lanka in February–April 1984 (Alling et al., 1991), and has since
been recorded on bottom-mounted instruments near Diego Garcia in all months except
February–April and July (Stafford et al., 2005). The second call type was recorded in late
December 1996 on the Madagascar Plateau in the presence of nominal pygmy blue whales
(Ljungblad et al., 1998). It has also been recorded at Diego Garcia in May–July (Stafford
et al., 2005) and off Crozet Island (Samaran et al., 2006). The third call type, first described
by McCauley et al. (2001) from moored hydrophones, has been recorded in south-western
Australian waters during November–June (McCauley et al., 2004; Stafford et al., 2005),
along the West Australian coast off Exmouth (21°S) in June–July and November–December
(R. D. McCauley, unpublished data) and along southern Australia from Bass Strait west-
wards to south-western Australia (R. D. McCauley, unpublished data).
The south-east Pacific blue whale call type was first recorded on 30–31 May 1970 at 43°36S
74°40W off Chile (Cummings & Thompson, 1971), and has been recorded year-round on a
hydrophone array in the eastern tropical Pacific, primarily at 8°S 95°W, with peak calling
from March–September (Stafford et al., 1999). These calls were also recorded off Peru at
6°54S 80°50W in November 2000 (T. Norris, unpublished data). In addition to this ‘normal’
call type, a different call type was recorded during biopsy approaches off Chile during the
1997–98 IWC survey, apparently in reaction to the rapid approach of the survey vessel
(Ljungblad & Clark, 1998).
The northern New Zealand call type consists of a single instance of these calls in the 1960s
(Kibblewhite et al., 1967) together with four records in 1997 (McDonald, 2006).
Combined distribution from all sources
Where blue whales were present, this was often confirmed by multiple sources (Fig. 10). For
example, although there were only rare detections of blue whales off northern New Zealand,
these records included catches, sightings, strandings and acoustic detections.
Monthly distribution
Most positional data were recorded during the austral summer season between October and
April (Fig. 11). During summer, records were nearly circumpolar especially between Novem-
ber and March. The Antarctic region between 160°W and 70°W was hardly exploited before
Distribution of southern blue whales 133
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Fig. 10. Distribution of blue whales in all months based on catches (¥), sightings (!), strandings ("), acoustic records (#) and Discovery mark positions ($). Grey is used
for positions "1973 and black for >1973.
134 T. A. Branch et al.
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Fig. 11. Monthly distribution of blue whales during October to March based on catches (¥), sightings (!), strandings ("), acoustic records (#) and Discovery mark
positions ($). Grey is used for positions "1973 and black for >1973. Acoustic locations are annotated with the call type using numbers: Antarctic (1), South-east Pacific
(2), New Zealand (3), Sri Lanka (4), Australia (5) and Madagascar (6); these numbers are concatenated when two or more call types were recorded at a single location.
Distribution of southern blue whales 135
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World War II, and was proclaimed a sanctuary from 1938/39 to 1954/55, after which catches
were legal between January and March only, explaining the near-absence of catches in this
region outside those months. During summer, blue whales were commonly recorded in
temperate latitudes off the west coast of South America, in the northern Indian Ocean, in the
Subantarctic, around southern Australia and in north-west New Zealand, but were largely
absent from African waters. In winter months (April–September), high catches were reported
off south-west Africa (especially Saldanha Bay), and Durban (Fig. 12). In these months,
sightings and strandings continued in other areas. It is also notable that catches were reported
in every month of the year at South Georgia, although numbers (and catch effort) decreased
greatly in the winter months.
DISCUSSION
The dataset assembled here allows for an updated examination of blue whale distribution and
its association with environmental factors, migration patterns and the relative status of
different populations of blue whales in the study area.
Distribution
Blue whales feed on euphausiids and other crustacean meso-zooplankton (e.g. Mackintosh &
Wheeler, 1929; Yochem & Leatherwood, 1985). To maintain their great energetic demands,
they search out the densest patches of their prey (Croll et al., 2005). It has previously been
accepted that blue whales in the study area (particularly Antarctic blue whales) feed in the
austral summer but fast during the winter breeding season (e.g. Mackintosh & Wheeler, 1929;
Mackintosh, 1966). However, as detailed below, we found that their distribution year-round
is linked to areas with known or inferred high densities of euphausiids, suggesting that their
winter distribution also may be influenced by feeding opportunities (cf. Reilly & Thayer,
1990; Croll et al., 2005).
Blue whale distribution in the study area is strongly linked to latitude. Close to the Antarctic,
blue whales were recorded along bands stretching across entire ocean basins, but at lower
latitudes they are progressively more clustered, localized and compressed along the continental
margins (Fig. 10). This pattern probably reflects euphausiid biogeography, with large Antarc-
tic krill Euphausia superba at the highest latitudes, mid-sized Euphausia species in the mid
latitudes and smaller Nyctiphanes species in coastal upwelling systems in the mid and low
latitudes (see maps in Brinton et al., 2000). However, until better region-wide data become
available, we must rely on environmental proxies for euphausiid aggregation such as bathym-
etry, frontal processes and phytoplankton biomass (Atkinson et al., 2004; Siegel, 2005).
Patterns of blue whale distribution in relation to environmental features are best summa-
rized in Figs 1 and 10. At the largest scale, blue whales generally occurred in regions with high
phytoplankton densities such as the productive Antarctic and Subantarctic waters, and in the
upwelling systems of the Arabian Sea and the west coasts of South America and Africa. A
major exception to this pattern is in the 35–45°S band between South America and Africa,
and extending into the Agulhas Retroflection south of Africa, where few blue whales were
reported despite high chlorophyll-aconcentrations. Conversely, annual mean chlorophyll-a
levels were intermediate to low south of Madagascar and around Australia, where blue whale
sightings were numerous. These areas, however, undergo seasonal blooming (Fig. 2), and are
thus under-represented in the annual mean. Blue whales were virtually absent year-round
from the mid-latitude central gyres with lowest chlorophyll-aconcentrations.
Blue whales were generally associated with waters deeper than the continental shelves.
Shallow-water records were typically from regions with narrow continental shelves, but blue
136 T. A. Branch et al.
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Fig. 12. Monthly distribution of blue whales during April to September based on catches (¥), sightings (!), strandings ("), acoustic records (#) and Discovery mark
positions ($). Grey is used for positions "1973 and black for >1973. Acoustic locations are annotated with the call type using numbers: Antarctic (1), South-east Pacific
(2), New Zealand (3), Sri Lanka (4), Australia (5) and Madagascar (6); these numbers are concatenated when two or more call types were recorded at a single location.
Distribution of southern blue whales 137
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whales were virtually absent from the wide continental shelves off south-east Argentina,
northern Australia and south-east New Zealand. In the Antarctic, they were most common
on deep continental slopes (Kasamatsu, Matsuoka & Hakamada, 2000). Frequent sightings
and strandings have been reported from Trincomalee Harbour, Sri Lanka, in waters shal-
lower than 200 m, but deeper water (>500 m) is found near to this harbour (Alling et al.,
1991). Blue whales also move through waters less than 50 m depth in Geographe Bay,
Australia (C. Burton, unpublished data), around Chiloé Island, Chile (Hucke-Gaete et al.,
2003), and in the Bonney Upwelling of south-east Australia, where the mean depth of 920
sightings was 93 m (P. Gill & M. Morrice, unpublished data).
Blue whale occurrence matched large-scale fronts closely in some regions, but not in others.
Frontal regions define water masses with distinct physical properties and production regimes,
which influence euphausiid biogeography (e.g. Longhurst, 1998). In addition, enhanced
frontal dynamics, such as interaction with bathymetric features, cross-frontal exchange,
splitting and merging, meandering, and eddy shedding, often result in front-associated phy-
toplankton blooms (Moore & Abbott, 2000, 2002). Antarctic catches were bounded to the
north by the Antarctic Polar Front, and pygmy blue whale distribution in the Subantarctic
was fairly well bounded by the Subantarctic Front and the North and South Subtropical
Fronts (Fig. 1). Off the west coasts of South America and Africa, distribution extended from
upwelling regions to the Equatorial Front. Blue whales south of Madagascar may be sup-
ported by biological enrichment from the interaction of the North Subtropical Front with the
steep bathymetry of the Madagascar Plateau; interactions of this front with the Broken
Plateau may similarly support aggregations west of Australia. However, there were no links
with any fronts for concentrations of blue whales in the northern Indian Ocean, coastal
Australia and around New Zealand.
The above discussion examined large-scale patterns of blue whale distribution in the study
area. There are also regional particularities that deserve additional consideration. We there-
fore focus in more depth on 10 regions of special interest.
Antarctic
It can safely be assumed from a variety of sources that nearly all blue whales in the Antarctic
are from the Antarctic (true) subspecies. First, based on the lengths of sexually mature females,
nearly all (99.2%) catches taken south of 52°S were Antarctic blue whales (Branch et al., 2007).
Second, genetic evidence shows a significant separation between samples taken south of 60°S
(Antarctic blue whales) and samples from the Indian Ocean (pygmy blue whales) (Conway,
2005; LeDuc et al., in press). Third, acoustic data south of 60°S from SOWER cruises (austral
summer) and moored instruments (year-round) have consistently recorded the distinctive
Antarctic-type 28-Hz tones (Ljungblad et al., 1998; Clark & Fowler, 2001; Širovic´ et al., 2004;
Stafford et al., 2004; McKay et al., 2005; Rankin et al., 2005; Ensor et al., 2006). To date, none
of the other blue whale call types have been recorded south of 60°S.
Antarctic blue whales have a continuous circumpolar distribution, although catches were
lower between 70°W and 160°W. Prior to 1938/39, little whaling was conducted in 70–160°W,
presumably because there were few blue whales there. From 1938/39 to 1954/55, this region
was proclaimed a sanctuary; thus, the majority of whaling in this region was conducted after
1954/55. The continuous circumpolar distribution of Antarctic blue whales is reinforced by
recoveries of Discovery marks showing that they sometimes disperse over time widely around
the Antarctic, as noted by previous authors (Brown, 1954, 1962). While they may show some
fidelity to particular IWC Management Areas (the IWC divides the Antarctic into six roughly
equal Areas for management purposes), they also cross the borders between Management
138 T. A. Branch et al.
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Areas and have been caught on several occasions more than 100 degrees of longitude from
their marking position. Circumpolar-wide acoustic records of 28-Hz tones further support
their continuous distribution (Ljungblad et al., 1998; Clark & Fowler, 2001; Širovic´ et al.,
2004; Stafford et al., 2004; McKay et al., 2005; Rankin et al., 2005; Ensor et al., 2006).
Nearly all blue whale catches in the Antarctic were between October and April (Figs 2 and
12). While Tynan (1998) found that highest krill densities and highest whale catches are
aligned with the Southern Boundary of the Antarctic Circumpolar Current (not shown here),
we found that the Antarctic Polar Front was a more useful indicator of the northern
boundary of the Antarctic catches. Where the Antarctic Polar Front was farther south
(70–130°W), the catches were more southerly, and where it was further north (50°W-60°E),
catches were more northerly. Antarctic krill presence is not associated with any one oceano-
graphic feature, but is determined by the presence of abundant phytoplankton near ice edges,
continental shelves and dynamic frontal regions (Atkinson et al., 2004; Siegel, 2005).
It is striking that recent Antarctic sightings are in a much narrower ring close to the pack
ice and the continental shelves (Figs 4 and 5), while most catches were further north. In part,
this may be explained by greater sighting effort (from the IDCR/SOWER surveys) south of
60°S. Additionally, the Antarctic pack ice has retreated since the 1960s (de la Mare, 1997;
Cotté & Guinet, 2007), although this conclusion is disputed by Ackley et al. (2003). As an
alternative, their narrower present-day distribution may be explained by the ‘basin model’ of
MacCall (1990): at higher densities, the Antarctic blue whales may have occupied a wider
habitat range, but now that they are depleted to <1% of their original abundance (Branch
et al., 2004), they are more concentrated close to the ice edge where krill is most abundant.
Central ocean basins
Blue whales are largely absent from the central portions of each of the major ocean basins
in the study area, which are notable biological deserts, as evidenced by the very low
chlorophyll-aconcentrations in these regions (Fig. 1; McClain, Signorini & Christian, 2004).
In the central South Pacific, two Soviet cruises in 1973/74 and 1974/75 found no blue
whales between 40°S and 60°S (Mikhalev, 1978), and the JSV database also recorded no
sightings in the South Pacific (20–50°S 90–150°W) despite 42 335 km of search effort.
Few blue whales were recorded from the central South Atlantic. Large-scale studies based
on ship reports reinforce this conclusion (Brown, 1958; Slijper, van Utrecht & Naaktege-
boren, 1964): sightings of rorquals (not identified to species) were nearly absent in the central
region while higher sighting rates were recorded close to the African coast and in the 30–40°S
latitude strip. However, these high rorqual sighting rates in 30–40°S in the South Atlantic
probably did not include any blue whales, given that in the JSV database only three blue
whales were sighted in 35–50°S, 10°E-65°W during 352 554 km of effort (0.005 groups per
1000 km assuming mean group size of 1.56). Furthermore, few Soviet blue whale catches were
taken in this band despite large catches of other cetacean species (Fig. 3; Yablokov et al.,
1998).
In the south-central Indian Ocean, blue whale records were completely absent although
numerous sightings and catches were recorded along the Australian coast, in the northern
Indian Ocean and south of about 35°S. Rorqual sightings from large-scale ship studies
matched the patterns observed in this paper: low sighting rates in the central Indian Ocean
contrasted with high sighting rates on the oceanic periphery (Brown, 1957; Slijper et al.,
1964). Soviet catch data show a similar pattern (Mikhalev, 2000), including zero blue whale
catches in the central Indian Ocean despite some catches of other species there (Fig. 3;
Yablokov et al., 1998).
Distribution of southern blue whales 139
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South-west Atlantic (Brazil, Uruguay and Argentina)
The lowest sighting rate in the study area was from Costinha, Brazil where only three sightings
were recorded during 46 273 hours of effort (da Rocha, 1983), to add to two Brazilian catches
(one of which was originally recorded as being either a bowhead or a blue, and whose identity
is thus questionable) and one stranding (Dalla Rosa & Secchi, 1997). A thorough review
concluded that blue whales are nearly absent from Brazil (Zerbini et al., 1997). Isolated
strandings were reported from Uruguay (Praderi, 1985) and Argentina (Burmeister, 1871,
1872), and in October 1993 the jawbones from a long-forgotten blue whale stranding were
discovered in central Patagonia (Reyes, 2006). Most likely these few blue whales off eastern
South America are Antarctic blue whales, although the Brazilian stranding could not be
assigned unambiguously to either the Antarctic or pygmy subspecies (Dalla Rosa & Secchi,
1997). It is a mystery why there are so few blue whale records from this region despite intensive
whaling and sighting effort (Figs 3 and 6; da Rocha, 1983), especially given its extensive use by
other large cetaceans (Zerbini et al., 1997; Croxall & Wood, 2002; Reyes, 2006) and areas of
high chlorophyll-a concentrations (Fig. 1b; Romero et al., 2006). However, it is worth noting
that the high chlorophyll-aconcentrations are over the broad continental shelf (Fig. 1a), which
is probably shallower than the depths preferred by blue whales.
South-western Africa
Large catches were recorded from Saldanha Bay (South Africa) (n=7969), Namibia
(n=1665), Angola (n=1917) and Congo (n=1). Saldanha Bay in particular was known to be
a place frequented by a high percentage of immature blue whales in addition to some very
large females (Mackintosh & Wheeler, 1929; Mackintosh, 1942). These catches occurred
throughout the highly productive upwelling system of the Benguela Current (Carr & Kearns,
2003). Despite large historical catches, only two sightings of blue whales have been recorded
from the entire west coast of Africa since 1973, suggesting that these blue whales were nearly
extirpated by whaling. Recently, no sightings were recorded in 3644 hours of survey effort
between March 2004 and September 2005 off central and northern Angola in deep waters (C.
Weir, personal communication). No strandings have ever been reported from this coast,
perhaps because it is sparsely inhabited. These blue whales are most likely to be Antarctic
blue whales because (i) Antarctic blue whales were severely depleted by whaling (Branch &
Butterworth, 2001b; Branch et al., 2004); (ii) an estimated >90% of sexually mature females
caught were Antarctic blue whales (Branch et al., 2007); and (iii) a detailed study found
that they were morphologically similar to Antarctic blue whales caught at South Georgia
(Mackintosh & Wheeler, 1929).
South-eastern Africa
Catches with positional data in this region were recorded only at Durban, South Africa, and
consisted of a mixture of immature and adult blue whales. In total, 2986 blue whales were
caught off Durban. Additional catches (positions not available) were taken in south-east
South Africa (n=417) and Mozambique (n=14) during 1911–16. Evidence from a variety of
sources suggests that most catches here were originally Antarctic blue whales but by the end
of the whaling period most catches and sightings were probably pygmy blue whales (Branch
et al., 2007). This is not surprising given the close proximity to known pygmy blue whale
grounds south of Madagascar (Best et al., 2003), and a pygmy blue whale reported caught at
Durban (Gambell, 1964). Sightings during 1968–75 were rare and concentrated in March–
May, while earlier catches peaked in May–July (Bannister & Gambell, 1965).
140 T. A. Branch et al.
© 2007 The Authors. Journal compilation © 2007 Mammal Society, Mammal Review,37, 116–175
Madagascar and Subantarctic (southern Indian Ocean)
This region of numerous sightings and catches is known to be primary pygmy blue whale
habitat in the summer. One of the highest sighting rates recorded was on the Madagascar
Plateau: 36 groups per 1000 km (Best et al., 2003), while 1607 whales were recorded in the
JSV database in the Subantarctic (2.9 groups per 1000 km in 35–50°S 30–100°E). These
sighting rates are 500 times greater than in the South Atlantic and South Pacific and an order
of magnitude greater than in the Antarctic. Calls recorded here in the presence of pygmy blue
whales are distinctive (Ljungblad et al., 1998) and have also been recorded north-east of
Madagascar near Diego Garcia (Stafford et al., 2005) and in the Subantarctic near Crozet
Island (Samaran et al., 2006). South of Madagascar, localized wind-driven upwelling occurs
in winter (Ho, Zheng & Kuo, 2004), and the East Madagascar Current regularly sheds
energetic eddies that feed into the Agulhas Current off south-eastern Africa (Quartly et al.,
2006). Sightings and catches extended over a broad area from Africa to Australia, and were
just south of a band of high eddy variability extending from Madagascar to Australia
(Palastanga et al., 2007).
Australia and Indonesia
Sighting rates off southern and western Australia were among the highest recorded (7.4–18.6
groups per 1000 km). These areas were also where Soviet whalers took large catches of pygmy
blue whales, and where relatively many strandings have been recorded. Given the near
continuous distribution of records from Tasmania to Indonesia, it is likely that these blue
whales form one population. Recordings of blue whales off western Australia include
Australia-specific calls, presumably from pygmy blue whales, which peak from February to
May, and limited numbers of Antarctic-type calls from May to October (Ljungblad et al.,
1997; McCauley et al., 2004; Stafford et al., 2004). Additionally, the 1898 stranding off
south-west Australia was of a physically immature Antarctic blue whale, 24.0 m in length
(Bannister et al., 2005). Thus, while the great majority of blue whales in this region are
probably pygmy blue whales, a few Antarctic blue whales migrate here in the austral winter.
Environmental factors driving biological enrichment and enhanced blue whale foraging in
this region include upwelling, eddy shedding and current meandering. Upwelling is most
evident along the southern coasts of Java and Sumbawa Islands, Indonesia (Hendiarti, Siegel
& Ohde, 2004), in the eastern Great Australian Bight (McClatchie, Middleton & Ward, 2006)
including the Bonney Upwelling region (Gill, 2002), and at Perth Canyon, Western Australia,
where a strong subsurface chlorophyll maximum (i.e. not evident in satellite imagery) sup-
ports seasonal blue whale foraging (Rennie, McCauley & Pattiaratchi, 2006). Eddy shedding
is evident in the Leeuwin Current (Fang & Morrow, 2003), and current meandering interacts
with upwelling around Halmahere Island, Indonesia (Christian et al., 2004).
Northern Indian Ocean
Numerous catches were recorded off Oman and Somalia, and around the Maldives and Sri
Lanka. Sightings and strandings were recorded year-round in high productivity portions of
the northern Indian Ocean, especially off Somalia (Small & Small, 1991), the Maldives
(Anderson, 2005) and Sri Lanka (Alling et al., 1991). Strandings were also reported from a
much wider area (Bangladesh, Burma, India and Pakistan) than sightings and catches.
Sighting rates were generally higher than in the Antarctic, except off Oman where sightings
were rare. Calls recorded from Sri Lanka (Alling et al., 1991) are distinct from those recorded
off Madagascar, Australia and around the Antarctic but have also been recorded south of the
equator at Diego Garcia (Stafford et al., 2005). This region encompasses the Arabian Sea, a
Distribution of southern blue whales 141
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productive upwelling region during the south-west monsoon (Longhurst, 1998). Localized
upwelling also occurs between the southern tip of India and Sri Lanka (Rao et al., 2006),
where blue whales are known to feed.
It has been suggested that northern Indian Ocean blue whales are a separate subspecies,
B. m. indica (Blyth, 1859). While this name is accepted as valid, and has nomenclatural priority
over both brevicauda (Ichihara, 1966) and intermedia (Burmeister, 1871), the distinguishing
features (if any) of northern Indian Ocean blue whales are poorly known (Rice, 1998). It seems
more likely that northern Indian Ocean and pygmy blue whales belong to the same subspecies,
based on Soviet catches, where the mean length of sexually mature females from the northern
Indian Ocean is 69 ft (21.0 m), nearly identical to that for pygmy blue whales from the southern
Indian Ocean, and in contrast to the ~84 ft (25.6 m) from Antarctic catches (Branch et al.,
2007). On the other hand, their geographical distribution is fairly discrete (Fig. 10), and their
breeding cycle is 6 months out of phase with those in the southern Indian Ocean (Mikhalev,
2000, p. 151). It is noteworthy that a resident population of humpback whales in the northern
Indian Ocean (particularly the Arabian Sea) also has a reproductive cycle shifted by 6 months
compared with the Southern Hemisphere (Mikhalev, 1997b).
South-east Pacific (Chile, Peru, Ecuador)
Sightings, strandings and catches were recorded throughout the waters of Chile, Peru,
Ecuador and the Galapagos in a nearly continuous distribution bounded to the south by the
South Subtropical Front and to the north by the Equatorial Front. This population is
supported by the rich upwellings along the extent of the Humboldt Current (Carr & Kearns,
2003), and by topographic and equatorial upwelling processes near the Galapagos (Palacios,
2004). Recent sighting rates from an offshore survey (Findlay et al., 1998) and from the
inshore Chiloé Island-Corcovado region (e.g. Hucke-Gaete et al., 2003; Galletti Vernazzani
et al., 2006) are one to two orders of magnitude higher than those recorded in the Antarctic
(from the IDCR/SOWER, JARPA and JSV surveys).
Several lines of evidence confirm that blue whales in Chilean waters are not from the same
population as those in the Antarctic. First, hundreds of blue whales were caught annually in
Chile in the 1960s (Clarke et al., 1978) at a time when Antarctic blue whales numbered less than
a thousand (Branch et al., 2004). Second, a feeding and nursing aggregation of blue whales was
discovered in southern Chilean waters during the summer when Antarctic blue whales should
be in polar waters (Hucke-Gaete et al., 2003). Finally, there was a distinct gap between the
southernmost sightings at 44°S and the northernmost Antarctic records at 64°S, corresponding
to the region between the South Subtropical Front and the Antarctic Polar Front (Fig. 10).
Acoustic data include a call type unique to the south-east Pacific (Cummings & Thompson,
1971; Stafford et al., 1999; T. Norris, unpublished data). In the eastern tropical Pacific, this
call type was paired with the Antarctic call type during June–September although the Ant-
arctic calls were recorded much more rarely (Stafford et al., 1999; Stafford et al., 2004).
The subspecific status of south-east Pacific blue whales remains a topic open for debate.
The gap of 20° latitude between their southernmost distribution and the northernmost
Antarctic records, and their high density peaking in summer months in Chile are evidence
that they are not Antarctic blue whales. Aguayo (1974) asserts that 10 out of 168 examined
Chilean catches were pygmy blue whales (but provides no details), and an examination of a
stranded individual (Van Waerebeek et al., 1997) suggested more affinity to Antarctic blue
whales than to pygmy blue whales. South-east Pacific blue whales have a unique acoustic call
type (Cummings & Thompson, 1971; Stafford et al., 1999; T. Norris, unpublished data).
Genetic evidence has suggested similar levels of divergences between Antarctic samples,
142 T. A. Branch et al.
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Indian Ocean samples and those from the south-east Pacific (LeDuc et al., 2007). The mean
length of sexually mature blue whales from Chile (23.5 m) is intermediate between pygmy
(21.0 m) and Antarctic (25.6 m) blue whales (Branch et al., 2007). These lines of evidence led
Branch et al. (2007) to hypothesize that these blue whales may belong to a separate as-yet
undescribed subspecies, although this remains to be demonstrated.
New Zealand and south-west Pacific islands
A distinct grouping of catches, sightings and strandings was recorded from New Zealand,
separated by the 155°E longitude line from blue whales recorded around Tasmania. In the
JSV database, no sightings were recorded in the Tasman Sea despite high search effort. It
seems reasonable to conclude that these blue whales are linked to those recorded directly
north of New Zealand. This area is influenced by frontal dynamics at the Subtropical Front
to the south and the Tasman Front to the north, and by upwelling at several sites along the
coast of New Zealand (Longhurst, 1998). Sounds produced off northern New Zealand differ
from those produced by pygmy blue whales from the Indian Ocean (McDonald, 2006;
McDonald et al., 2006); however, these sounds were only recorded four times during a full
year of monitoring and just once from acoustic data monitored in the early 1960s (Kibble-
white et al., 1967; McDonald, 2006). Two carefully measured New Zealand strandings are
too long to have been pygmy blue whales: a 26.5 m individual in February 1908 (Waite,
1912), and a 27.4 m blue whale in April 1978 (A. N. Baker, unpublished data). Matters are
complicated further in that reported Soviet catches in this area do not include length data but
were considered to be pygmy blue whales (Mikhalev, 2000) and because Antarctic calls have
been recorded from this area in the winter months (McDonald, 2006). The available evidence
suggests that blue whales recorded here in austral summer months are probably a separate
population of pygmy blue whales but further work on morphology, acoustics and genetics is
needed to clarify their relationship to the described subspecies.
Migration
Antarctic blue whales
The classic theory for Antarctic blue whales holds that they migrate to the Antarctic in the
austral summer to feed, and then migrate to a variety of more northerly locations in the
winter to calve and mate (Mackintosh, 1966). Good supporting evidence is available for
the winter migration of Antarctic blue whales to the west coast of South Africa, Namibia and
Angola (e.g. Best, 1998). First, large females were recorded in south-west African locales with
similar morphology to blue whales at South Georgia (Mackintosh & Wheeler, 1929). Second,
Antarctic catches peaked in the austral summer, and south-west African catches peaked in
the austral winter. Third, south-west African catches plummeted to near zero with identical
timing to the substantial depletion in the Antarctic. Fourth, only two sightings have been
recorded in the region since whaling ceased (although effort is limited), implying that blue
whales off south-west Africa remain substantially depleted.
Similar evidence links Durban with Antarctic blue whales: size distribution, seasonal
distribution of catches and a plummeting catch per unit effort (Best, 2003). However, later
catches and sightings off Durban were primarily in March–May instead of the earlier catch
peak in June–July; catch per unit effort decreased to 3% (Best, 2003) instead of the 0.3% levels
expected (Branch et al., 2004); a pygmy blue whale was caught there in September 1963
(Gambell, 1964); and four out of 12 pregnant blue whales caught at Durban were shorter than
75 ft (IWC catch database). These data suggest that in later years most blue whales encoun-
tered at Durban were pygmy blue whales.
Distribution of southern blue whales 143
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In areas other than southern Africa, the main evidence for migration comes from acoustic
detections of the characteristic 28-Hz Antarctic call type and occasional strandings of
Antarctic-length blue whales. Antarctic blue whale calls have been recorded in winter months
in a variety of locations: the eastern tropical Pacific, the central Indian Ocean, south-west
Australia and northern New Zealand (Stafford et al., 1999; McCauley et al., 2004; Stafford
et al., 2004; Stafford et al., 2005; McDonald, 2006). These call detections are generally
infrequent, suggesting small numbers of calling blue whales. Strandings might be expected to
shed light on migration patterns but few unambiguous Antarctic blue whales have stranded
and been examined: notably a 24.0 m physically immature blue whale in Australia in 1898
(Bannister et al., 2005), a 26.5 m female in New Zealand in February 1908 (Waite, 1912), and
a 27.4 m individual in New Zealand in April 1978 (A. N. Baker, unpublished data).
While the acoustic detections provide evidence that Antarctic blue whales migrate to
northerly locations in winter, it is still unknown what proportion migrate. Moored acoustic
devices along the Western Antarctic Peninsula (Širovic´ et al., 2004) and in East Antarctica
(67°S 70°E) (McKay et al., 2005) detected Antarctic blue whales year-round. Admittedly,
these acoustic detections were greatly reduced in winter months, but it is likely that this
reduction was partly due to the encroachment of heavy ice cover over the acoustic devices
(Širovic´ et al., 2004), forcing the blue whales northwards. At South Georgia, although few
vessels attempted whaling in the winter months, Risting (1928, p. 20) reported that 559 blue
whales were taken during July–September in 1914–18, i.e. 5.0% of the 11 114 blue whales
taken in those years (source: IWC). Hinton (1915, p. 155) also records that while hump-
backs were present only between October and March around South Georgia, ‘finback and
blue whale are to be found around the island at all times’. Thus, at least some Antarctic
blue whales do not migrate northwards in winter. No information is available from Dis-
covery marks since these were recovered only in the Antarctic (n=103) and Subantarctic
(n=1) during summer months. Overall, the available evidence suggests that Antarctic blue
whales generally do migrate to northerly locations in winter, although some overwinter in
the Antarctic.
Pygmy blue whales
The migration patterns of pygmy blue whales are poorly known. High densities observed
during summer months in the northern Indian Ocean, off southern Madagascar and Austra-
lia and around New Zealand provide evidence that these blue whales do not migrate to the
Antarctic (Ichihara, 1966; Kato et al., 1995; Mikhalev, 2000; Gill, 2002; Best et al., 2003).
In the northern Indian Ocean, blue whales are present around Sri Lanka and India in all
months of the year and seasonally around the Maldives (Alling et al., 1991; Anderson, 2005).
The call type recorded off Sri Lanka from February to April was recorded from Diego Garcia
from May to December (except July), suggesting some movement between these two areas on
a seasonal basis. A more fine-scale analysis of seasonal movements within the northern
Indian Ocean is ongoing and will be reported separately.
The pygmy blue whales recorded south of Madagascar appear to move southwards and
spread longitudinally in the southern Indian Ocean in the summer. In January through
March, pygmy blue whales are distributed almost continuously in the Subantarctic between
Africa and Australia (Fig. 11). The call type recorded south of Madagascar in December was
recorded in Diego Garcia (6°18S 71°E) in May–July (Stafford et al., 2005), suggesting a
northern migration in winter.
Around Australia and Indonesia, the monthly data suggest a migratory link between
Australia and Indonesia around the western coast of Australia. As shown in Figs 11 and 12,
144 T. A. Branch et al.
© 2007 The Authors. Journal compilation © 2007 Mammal Society, Mammal Review,37, 116–175
blue whales have been recorded in Indonesian waters during May to November while high
concentrations are reported from the southern coast of Australia mostly during the austral
summer (November to May). Acoustic detections off West Australia (21°S) record blue
whales apparently migrating northwards in June–July and southwards in November–
December (R. D. McCauley, unpublished data). In July–October the acoustic detections
from Cape Leeuwin, Australia (35°S 114°E) included Antarctic blue whales only, but from
November to June Australian call types were often recorded there (McCauley et al., 2004;
Stafford et al., 2004).
Off north-western New Zealand there is little evidence for migration, although it
seems reasonable to hypothesize that some blue whales migrate from New Zealand north-
wards to the Pacific islands in winter. These blue whales were described as pygmy blue
whales in Soviet catches (Mikhalev, 2000), although length data are not available for
confirmation.
South-east Pacific blue whales
In the south-east Pacific, sightings and catches of blue whales peak in the summer months,
while in August to November there are numerous records off Peru and the Galapagos. These
data can be used to infer a migration from southern Chilean waters in summer to more
northerly regions in winter, although the data also show that some blue whales remain in each
of these regions all year.
Population status
Since the type and amount of effort differ substantially from region to region, the resulting
sighting rates are only a qualitative measure of the status of the blue whale populations
discussed here. For Antarctic blue whales, sightings remain rare in the Antarctic (0.17–0.52
per 1000 km) despite considerable effort during dedicated sightings surveys. Sightings are
also concentrated at the edge of the pack ice, whereas historical catches were more broadly
distributed, especially in the summer months. Recorded sightings are also rare (only two
since the 1960s) off south-west Africa where large catches of Antarctic blue whales were
taken in the 20th century (C. Allison, IWC catch database). This pattern is consistent with
substantial depletion of Antarctic blue whales to a low point of 0.07–0.29% of pre-
exploitation levels in 1973 (Branch et al., 2004). Until recently, there was little evidence for
recovery in this subspecies, but Branch et al. (2004) showed statistical evidence that they
are increasing at 7.3% per year (95% interval 1.4–11.6%), while remaining below 1% of
their original levels.
Within the known distribution range of pygmy blue whales (Indian Ocean including
Indonesian waters, south of Australia and north of New Zealand), there are areas with
sighting rates one to two orders of magnitude higher than in the Antarctic. This is of
particular interest because of the intensive effort associated with Antarctic sighting surveys
compared with the lower effective effort in many pygmy blue whale areas. This may reflect a
higher density and perhaps abundance of pygmy blue whales compared with Antarctic blue
whales, although this may only apply to specific regions where survey effort has been directed.
Given that catches of pygmy blue whales were much lower than Antarctic blue whales
(~13 000 vs. >330 000; Branch et al., 2004), and current densities in at least some places are
higher, it is clear that pygmy blue whales are less depleted at present than Antarctic blue
whales, although their status remains highly uncertain. Relatively high numbers of recent
sightings and strandings of south-east Pacific blue whales, and a lack of decline in catches in
Distribution of southern blue whales 145
© 2007 The Authors. Journal compilation © 2007 Mammal Society, Mammal Review,37, 116–175
the 1960s, suggest that this population is also less depleted than in the Antarctic, although,
again, their status remains uncertain.
ACKNOWLEDGEMENTS
We are grateful for sightings and strandings contributed, and assistance received in many
different ways, from the following sources: A. Alling, J. Barendse, L. Bedriñana, C. W. Clark,
R. Constantine, J. Cotton, B. M. Dyer, P. Ensor, K. Evans, B. Haase, S. Heinrich, D.
Hyrenbach, T. A. Jefferson, C. Kemper, F. Kennedy, S. Kromann, R. G. LeDuc, A. R.
Martin, M. A. McDonald, S. A. Mizroch, M. J. Moore, S. Ohsumi, P. Olson, V. Peddemors,
R. L. Pitman, R. Praderi, S. Reilly, D. Rice, H. Shigemune, A. Širovic´, E. Sullivan, P. Taylor,
C. T. Tynan, R. Veit, I. Visser, C. Weir, A. N. Zerbini, members of the Oman Whale and
Dolphin Research Group (R. Baldwin, T. Collins, L. Ponnampalam, F. Kennedy and G.
Minton) and the New Zealand Department of Conservation. Frontal paths in the Southern
Ocean were provided by I. M. Belkin, J. K. Moore and A. H. Orsi and the Costa Rica Dome
by P. C. Fiedler. Chlorophyll-a data were obtained from the SeaWiFS Project, NASA/
Goddard Space Flight Center and ORBIMAGE. Helpful comments on the manuscript were
received from R. R. Reeves, P. J. Clapham and an anonymous reviewer. D.M.P. was sup-
ported by award No. N00014-05-1-0045 from the U.S. National Oceanographic Partnership
Program. T.A.B. is very grateful for funding from the IWC and the South African National
Antarctic Programme, without which this project would never have been attempted.
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APPENDIX 1
Coauthors:
T. A. Branch: Marine Research Assessment and Management Group, Department of
Mathematics and Applied Mathematics, University of Cape Town, Rondebosch 7701,
South Africa.
K. M. Stafford: Applied Physics Lab, University of Washington, 1013 NE 40th, Seattle, WA
98105, USA.
D. M. Palacios: Joint Institute for Marine and Atmospheric Research, University of Hawaii,
1000 Pope Road, Marine Sciences Building, Room 312, Honolulu, HI 96822, USA; and
Environmental Research Division, Southwest Fisheries Science Center, NOAA Fisheries,
1352 Lighthouse Avenue, Pacific Grove, CA 93950-2097, USA.
C. Allison: International Whaling Commission, The Red House, 135 Station Road, Imping-
ton, Cambridge, CB4 9NP, UK.
J. L. Bannister: The Western Australian Museum, Locked Bag 49, Welshpool DC, WA 6986,
Australia.
Distribution of southern blue whales 155
© 2007 The Authors. Journal compilation © 2007 Mammal Society, Mammal Review,37, 116–175
C. L. K. Burton: PO Box 1076, Dunsborough, WA 6281, Australia.
E. Cabrera: Centro de Conservacion Cetacea (CCC), Casilla 19178, Correo Lo Castillo,
Santiago, Chile.
C. A. Carlson: College of the Atlantic, Bar Harbor, Maine, USA.
B. Galletti Vernazzani: Centro de Conservacion Cetacea (CCC), Casilla 19178, Correo Lo
Castillo, Santiago, Chile.
P. C. Gill: Blue Whale Study, Australocetus Research, C/- Post Office, Narrawong, Vic. 3285,
Australia.
R. Hucke-Gaete: Instituto de Ecología y Evolución, Universidad Austral de Chile, Casilla
567, Valdivia, Chile.
K. C. S. Jenner: Centre for Whale Research (WA) Inc., PO Box 1622, Fremantle, WA 6959,
Australia.
M.-N. M. Jenner: Centre for Whale Research (WA) Inc., PO Box 1622, Fremantle, WA 6959,
Australia.
K. Matsuoka: The Institute of Cetacean Research, 4-5, Toyomi-cho, Chuo-ku, Tokyo
104-0055, Japan.
Y. A. Mikhalev: South-Ukrainian Pedagogical University, Solnechnaya 10, no. 45, Odessa
65009, Ukraine.
T. Miyashita: Cetacean Resources Management Section, National Research Institute of Far
Seas Fisheries, 5-7-1 Orido, Shimizu-ku, Shizuoka 424-8633, Japan.
M. G. Morrice: Whale Ecology Group, School of Life and Environmental Sciences, Deakin
University, PO Box 423, Warrnambool, Vic. 3280, Australia.
S. Nishiwaki: The Institute of Cetacean Research, 4-5, Toyomi-cho, Chuo-ku, Tokyo
104-0055, Japan.
V. J. Sturrock: 41 Wasley St, Mount Lawley, WA 6050, Australia.
D. Tormosov: Ulitsa Karla Marksa, D.76 KV5, Kaliningrad 236000, Russian Federation.
R. C. Anderson: P.O. Box 2074, Male’, Republic of Maldives.
A. N. Baker: 8 Waters Lane, RD 2 Kerikeri, Bay of Islands, New Zealand.
P. B. Best: MRI Whale Unit, c/o South African Museum, PO Box 61, Cape Town, 8000,
South Africa.
P. Borsa: I R D Génétique des Populations, BP A5, 98848 Nouméa cedex,
Nouvelle-Calédonie.
R. L. Brownell, Jr: Southwest Fisheries Science Center, NOAA Fisheries, 1352 Lighthouse
Avenue, Pacific Grove, CA 93950-2097, USA.
S. Childerhouse: Marine Conservation Unit, Department of Conservation, Level 5, 53
Boulcott St, PO Box 10-420, Wellington, New Zealand.
K. P. Findlay: Oceanography Department, University of Cape Town, Private Bag,
Rondebosch 7701, South Africa.
T. Gerrodette: Southwest Fisheries Science Center, NOAA, U.S. National Marine Fisheries
Service, 8604 La Jolla Shores Drive, La Jolla, CA 92037, USA.
A. D. Ilangakoon: 215 Grandburg Place, Maharagama, Sri Lanka.
M. Joergensen: Broagergade 1, 3.th., 1672 Copenhagen V., Dk Denmark.
B. Kahn: APEX Environmental, Suite 102, Jl. Bypass Ngurah Rai No. 379, Sanur 80228,
Bali, Indonesia.
D. K. Ljungblad: Ljungblad Associates, P.O. Box 6, Elk Mountain, WY 82324, USA.
B. Maughan: 9 Bovet St, Wellington, Somerset, TA21 8JJ, UK.
R. D. McCauley: CMST Curtin University, GPO Box U 1987, Perth 6845, Western
Australia, Australia.
156 T. A. Branch et al.
© 2007 The Authors. Journal compilation © 2007 Mammal Society, Mammal Review,37, 116–175
S. McKay: Whale Ecology Group, School of Life and Environmental Sciences, Deakin
University, PO Box 423, Warrnambool, Vic. 3280, Australia.
T. F. Norris: Bio-Waves, Inc., 517 Cornish Dr, Encinitas, CA 92024, USA.
Oman Whale and Dolphin Research Group: P.O. Box 2531, CPO 111, Sultanate of Oman.
S. Rankin: Southwest Fisheries Science Center, NOAA, U.S. National Marine Fisheries
Service, 8604 La Jolla Shores Drive, La Jolla, CA 92037, USA.
F. Samaran: Centre d’Etudes Biologiques de Chize, CNRS, Villiers-en-Bois, France.
D. Thiele: Whale Ecology Group, School of Life and Environmental Sciences, Deakin
University, PO Box 423, Warrnambool, Vic. 3280, Australia.
K. Van Waerebeek: Peruvian Centre for Cetacean Research (CEPEC), Museo de Delfines,
Pucusana, Peru.
R. M. Warneke: Blackwood Lodge, 1511 Mt Hicks Road, Wynyard 7325, Australia.
Distribution of southern blue whales 157
© 2007 The Authors. Journal compilation © 2007 Mammal Society, Mammal Review,37, 116–175
APPENDIX 2
List of sources used to obtain sightings data together with the number of associated records, the listed number of groups sighted and the number of
whales sighted, alphabetized by source name. A ‘group’ could be either a school or feeding aggregation depending on the source. Listed sightings are
those with associated positions, many papers noted additional sightings without positions. Latitudes and longitudes are given in whole degrees and
rounded to encompass the study region. Where sources are ‘unpubl.’ this means ‘unpublished data’. For totals, each record contains !1 group and
!1 whale. Mean group size is based on all records containing both the number of groups and number of whales. Total effort in days is based on the
assumption that 10 hours of effort equals 1 day. For records from the eastern tropical Pacific only the sightings and effort south of 5°N were included.
Source Region Dates Effort Records Groups Whales Ave group size
Aguayo (1974) Coastal Chile 43–46°S Mar, Dec 1966 Not recorded 2 2 9 3.67
Aguayo et al. (1998) SE Pacific 26–34°S
91–111°W
Sep 1994, Jun 1995 770.5 hours 3 3 6 2.00
Alling et al. (1991) East coast, Sri Lanka Jan–Apr 1983–84 890 hours (49 sightings) 138 138
Anderson (2005), R. C.
Anderson unpubl.
Maldives Nov–Apr 1999–2004 161 days (11 sightings) 14 14 15 1.07
Anonymous (1987a) Oman 28 Oct 1985 Opportunistic 1 1 2 2.00
A. N. Baker, unpubl. New Zealand 171–177°E
33–42°S
1981, 1984, 1998–2004 Opportunistic 31 31 40 1.29
Ballance et al. (1996),
Ballance & Pitman
(1998)
Indian Ocean Mar–Jul 1995 92 days; 403.9 hours;
9783.9 km
17 17 27 1.59
Ballance et al. (2001) Maldives 3–8°N 72–74°E Apr 1998 20 days; 155.5 hours;
1700 km
4 4 4 1.00
Best et al. (2003) Madagascar Plateau
25–35°S 40–45°E
Dec 1996 23 days; 2859.9 km 103 103 131 1.27
P. B. Best, unpubl. Saldanha Bay, South
Africa
1964–2003 Opportunistic 4 4 4 1.00
P. B. Best, unpubl. Durban, South Africa Mar–Sep 1968–75 5545 boat days +1592 385
aerial km
62 62 71 1.15
Blokhin (1981) Southern Australia 29–45°S
113–148°E
2–28 Mar 1979 5839 km 7 7 23 3.29
Borsa & Hoarau (2004) New Caledonia, 22°S
167°E
29 Dec 2001–27 Jan 2002 Opportunistic 1 1 1 1.00
P. Borsa, unpubl. Kerguelen Is., 48°S 71°E Mar 1985 Opportunistic 1 1 1 1.00
158 T. A. Branch et al.
© 2007 The Authors. Journal compilation © 2007 Mammal Society, Mammal Review,37, 116–175
P. Borsa, unpubl. Indonesia, 2°N-11°S
122–137°E
1995–2004 270 hours 2 2 7 3.50
Bowles et al. (1994) Heard Island 53–54°S
74–75°E
19 Jan-3 Feb 1991 162.75 hours; 2412 km 2 2 2 1.00
C. L. K. Burton,
unpubl.
Geographe Bay, Australia
34°S 115°E
Sep–Dec 1994–2005 750 days; ~2600 hours
(372 whales)
126 126 270 2.14
J. L. Bannister & C. L.
K. Burton, unpubl.
Western Australia 31–33°S
115°E
Nov–May 2000–05 12 209.2 aerial km (227
sightings)
252 252 282 1.12
Cabrera, Carlson &
Galletti Vernazzani
(2005), Galletti
Vernazzani et al.
(2005, 2006)
NW Chiloé Island, Chile
40–43°S 73–75°W
Feb–Apr 2004–06 108.3 hours; 1714.2 km
(138 sightings)
184 184 321 1.74
Cawthorn (1983) New Zealand 38°S 141°E Feb 1982 Opportunistic 1 1 1 1.00
Cawthorn (1988) New Zealand 40°S 139°E Jul–Aug 1986 Opportunistic 1 3 21 7.00
Chittleborough (1953) Western Australia 23°S
114°E
Sep–Oct 1952 Not recorded 1 1 1 1.00
Clarke & Ruud (1954) Antarctic 53–62°S
47°W-15°E
Nov–Dec 1953 27 days 12 35
Clarke et al. (1978) Chile 28–37°S Nov–Dec 1964 3876 km 3 3 4 1.33
Corbett (1994) S Indian Ocean, Mauritius Jul 1991–Jul 1992 16 days 8 8 9 1.13
Cummings &
Thompson (1971)
Guafo Island, Chile 44°S
74°W
30–31 May 1970 Opportunistic 1 4
da Rocha (1983) Costinha, Brazil 1966–1981 2771 days; 46 273 hours;
~943 000 km
3 3
de Boer (2000) Antarctic, Indian Ocean Nov 1999–Jan 2000 22 920 km 1 5 10 2.00
Donovan (1984a,b) Peru 10°S-10°N 78–110°W Nov–Dec 1982 16 437 km 12 12 16 1.33
B. M. Dyer, pers.
comm.
Marion Island 47°S 38°E Apr 2005 Opportunistic 3 3 8 2.67
Eyre (1995) Sydney, Australia to Suez
Canal
May–Jul 1993 45 days; 16 974 km 4 4 4 1.00
Eyre (2000) Mauritius to Singapore Apr 2000 15 days; 6130 km 1 1 1 1.00
Findlay et al. (1998) Chile 18–53°S Dec 1997–Jan 1998 389 hours 58 minutes;
8248.6 km
40 40 48 1.20
Gambell, Best & Rice
(1975)
SW Indian Ocean 20–42°S
30–67°E
Nov 1973–Feb 1974 13 271 km 7 7 15 2.14
Distribution of southern blue whales 159
© 2007 The Authors. Journal compilation © 2007 Mammal Society, Mammal Review,37, 116–175
Table A2. (Continued)
Source Region Dates Effort Records Groups Whales Ave group size
Gill (2002), P. C. Gill,
unpubl.
Victoria, Australia 37–40°S
139–144°E
Feb 1998–May 2002 38 996 aerial km (290
sightings)
358 358 532 1.49
P. C. Gill & M. G.
Morrice, unpubl.
Victoria, Australia 35–40°S
134–144°E
Dec 2002–Feb 2006 Unknown 729 729 1013 1.39
Gordon, Papastavrou
& Alling (1986)
Trincomalee Bay, Sri
Lanka 8°N 81°E
Mar 1984 Opportunistic 6 6
Gunaratna,
Obeyesekera &
Hahn (1985)
SW Sri Lanka 5–7°N
79–81°E
May 1985 6 days 1 1 2 2.00
B. Haase, pers. comm. Galapagos Islands 28 Feb 2003 Opportunistic 1 1 1 1.00
Hucke-Gaete (2004),
Hucke-Gaete et al.
(2003, 2005, 2006),
R. Hucke-Gaete,
unpubl.
Coastal Chile 29–53°S Jan–Dec 1998,
2001–2006;
but mostly Jan–Apr
15.72 aerial hours (23
sightings);
625.36 boat hours (118
sightings)
158 158 429 2.72
D. Hyrenbach, pers.
comm.
S Indian Ocean 47°S 67°E Feb 2004 Opportunistic 2 2 2 1.00
IDCR/SOWER, IWC
unpubl.
Surveys south of 60°S, plus
transits
Dec–Mar 1978–2005 237 988.1 km (124
sightings)
242 242 490 2.01
A. D. Ilangakoon,
unpubl.
North-west Sri Lanka
6–9°N 79–82°E
1987, 1994, 2003–05 63 hours 49 minutes;
617.2 km (1 sighting)
15 15 25 1.67
JARPA, Matsuoka
et al. (2006),
K. Matsuoka & S.
Nishiwaki, unpubl.
Antarctic and S Indian
Ocean,
40°E-180°–140°W,
mostly S of 60°S
Nov–Mar 1989–2005 423 928 km (143
sightings)
253 253 432 1.71
K. C. S. Jenner,
M.-N. M. Jenner
& V. J. Sturrock,
unpubl.
Western Australia, 20–33°S
113–117°E
1993, Feb 2000–Apr
2005
1612 hours; 24 572 km 455 455 548 1.20
160 T. A. Branch et al.
© 2007 The Authors. Journal compilation © 2007 Mammal Society, Mammal Review,37, 116–175
M. Joergensen, unpubl. Chile 43–44°S, 49°S Feb 2004 1 day 10 10 15 1.50
JSV, Miyashita et al.
(1995),
T. Miyashita,
unpubl.
Southern Hemisphere Dec 1965–Feb 1987 4 827 370 km (2520
whales)
799 2410
Kahn (2000, 2002) Komodo, Indonesia Sep–Oct 2000, Oct 2001 227.25 hours; 4430.7 km 3 3 3 1.00
Kahn (2005) Solor-Alor, Indonesia Apr–May 2005 79.75 hours; 1162.9 km 8 8
Kasuya & Wada
(1991)
Equatorial Indian Ocean Mar 1982 4295 km 2 8
Kato et al. (1996) Southern Australia 31–45°S
113–149°E
Dec–Jan 1996 ~44 days 52 52 60 1.15
Leatherwood (1986) Antarctic, S. Indian 1874, 1979 Opportunistic 14
Leatherwood et al.
(1984)
Northern Indian Ocean; Sri
Lanka
Apr 1983; 3 May 1983 4023 km (1 sighting);
4 hours (9 sightings)
9 9 9 1.00
A. R. Martin, pers.
comm.
West of South Georgia 10 Feb 2006 Opportunistic 2 16
B. Maughan, unpubl. South Atlantic 0–70°S Oct–Apr 1997–2001 Opportunistic 4 4
Moore et al. (1999) Falkland to S Georgia
51–55°S 34–58°W
Jan–Feb 1997 2266 km 1 1 2 2.00
Ohsumi & Shigemune
(1993)
Pacific 36°N-30°S
141°E-145°W
Aug–Oct 1957 13 479 km (in Southern
Hemisphere)
23 23 44 1.91
Oman Whale and
Dolphin Research
Group, unpubl.
Oman 16–24°N 54–59°E Oct–Apr 1996–2005 12 417 km (4 sightings) 7 7 11 1.57
Palacios (1999a,b), D.
M. Palacios, unpubl.
Galapagos 3°N-3°S
90–107°W
1978–1995 190 days; 31 390 km (8
sightings)
17 17 36 2.11
Parker (1978) Melbourne, Australia to
Mawson, Antarctica
Dec 1976, Feb–Mar
1977
34 days; ~136 hours 1 2
V. Peddemors, pers.
comm.
Indian Ocean 37°S 10°E 20 Oct 1987 Opportunistic 1 1 2 2.00
R. L. Pitman, pers.
comm.
Peru; South Georgia Mar 1982, Dec 1985; Jan
2003
Opportunistic 17 17 52 3.06
Puddicombe (1986) New South Wales,
Australia 37°S 150°E
16 Aug 1984 Opportunistic 1 1 1 1.00
Distribution of southern blue whales 161
© 2007 The Authors. Journal compilation © 2007 Mammal Society, Mammal Review,37, 116–175
Table A2. (Continued)
Source Region Dates Effort Records Groups Whales Ave group size
Ramirez (1985) Peru, 3–6°S 81–84°E Oct–Dec 1983 3014.6 hours (852.2
searching)
10 79
Rudolph, Smeenk
& Leatherwood
(1997)
Indonesian archipelago Jun–Sep 1990–93 Opportunistic 3 3 6 2.00
Slijper (1962) Indian Ocean 11°N 60°E 23 Sep 1953 Opportunistic 1 40
Small & Small (1991) Somalia 10–14°N 44–52°E Aug 1985–May 1987 2615 hours; 32 062.9 km 6 6
SWFSC cruises, T.
Gerrodette, unpubl.
Eastern tropical Pacific Aug–Nov 1986–1990,
1992, 1998–2000,
2003, 2006
104 691.9 km (47
sightings)
57 57 120 2.11
Thiele (2005) North-west Australia
13–16°S 123–130°E
Sep 2004 125 hours 1 1 1 1.00
D. Thiele, unpubl. Australia to Antarctic Jul 1995–Dec 2004 ~1244 days 25 25 54 2.16
Tynan (1996) Southern Indian Ocean
82–115°E
Dec 1994–Jan 1995 50 days 2 2 2 1.00
Valdivia et al. (1983) Peru 3–8°S 80–86°W Feb–Mar 1982 3400 km 14 14
Van Waerebeek et al.
(1997)
Chile 36–44°S 74–75°W 1970, 1982, 1983, 1995 Opportunistic 4 4 9 2.25
Wade & Friedrichsen
(1979)
Eastern tropical Pacific Jan–May 1971, 1975–76 Unknown 1 1 1 1.00
Wheeler (1946) Central Atlantic 20°S Aug–Sep 1943 15 days 1 1 1 1.00
Whitehead et al. (1983) Sri Lanka and Maldives Oct–Dec 1983 40 days 1 1 1 1.00
Wray & Martin (1983) Indian Ocean 45°S-7°N
42–96°E
Oct–May 1836–1888 Opportunistic 15 15
Total 4383 !4389 !8058 1.56
162 T. A. Branch et al.
© 2007 The Authors. Journal compilation © 2007 Mammal Society, Mammal Review,37, 116–175
APPENDIX 3
Blue whale strandings in the Southern Hemisphere and northern Indian Ocean, ordered by date of stranding. The source is the reference from which
the information was obtained; if this was not the original reference, then the original reference is also listed. Where species identity was uncertain the
stranding was generally excluded from this list, unless later authors confirmed that it was a blue whale. Most locations were obtained by reading the
position from Google Earth, and were typically accurate to at most two decimal places; however, four decimal places are given to account for
strandings with more detailed information and to avoid strandings being placed on land. Negative latitudes are south of the equator; negative
longitudes are west of the Greenwich meridian.
Source Date Sex Length (m) Latitude Longitude Position name Notes
Guiler (1978) from Hobart Town
Gazette
6/5/1825 29.3 -42.7833 147.0667 New Norfolk, Derwent River,
Tasmania, Australia
Blyth (1859) 15/8/1842 27.4 21.0000 92.1833 Chittagong coast about 21°N,
Bangladesh
ID uncertain, length ‘as alleged’
Blyth (1859) 1851 25.6 18.7833 93.9667 Juggu/Amherst Is., S of Ramri, E
of Cheduba on Arakan coast,
Burma (Myanmar)
Skeleton in Indian Museum,
Calcutta (Jones, 1953);
according to Rice (1998) some
authors erroneously recorded
location as Sondip or Sordip
Blyth (1859) c.1858 27.4 8.8833 76.5667 Quilon, India ID uncertain
Dixon & Frigo (1994) and M’Coy
(1867)
Aug 1866 27.4 -38.3333 144.3000 Jan Juc, outside Port Phillip
Heads, Victoria, Australia
Total length recorded, baleen
black
Burmeister (1871, 1872) 14/8/1866 Female 17.7 -34.3000 -58.4500 Mouth of Río Luján, near Buenos
Aires, Argentina
Type specimen for B. m.
intermedia
Anonymous (1874) 25/7/1874 26.5 -41.0927 146.0921 West side of Leven Estuary
(Ulverstone), Tasmania,
Australia
Length exclusive of tail, weight
estimated 100–150 tons
Moses (1947) 1874 14.4 12.8333 74.8333 Mangalore, India Skeleton in Madras Museum, ID
confirmed in Gibson-Hill (1950)
Anderson (1878) ~Nov 1874 22.5000 91.4167 Sandwip (formerly Sondip) Island,
Bangladesh
Young whale
De Silva (1987) from Murray
(1884)
1879 24.8000 67.0167 Clifton beach, Pakistan
R. M. Warneke, unpubl. 27/7/1887 19.2 -38.3333 145.4167 West of Warrnambool, Victoria,
Australia
Distribution of southern blue whales 163
© 2007 The Authors. Journal compilation © 2007 Mammal Society, Mammal Review,37, 116–175
Table A3. (Continued)
Source Date Sex Length (m) Latitude Longitude Position name Notes
De Silva (1987) from Haly (1894) Sep 1894 19.8 6.2333 80.0500 Ambalangoda, Sri Lanka Skeleton in Colombo Museum
Bannister et al. (2005) 1898 24.0 -33.6500 115.3167 Near Busselton, Western
Australia
Physically immature Antarctic
blue whale, skeleton in WA
Museum
Pillay (1926) and James &
Soundararajan (1979)
1901 ~22 8.1000 77.4000 Rajakamangalam, 5 miles south
of Muttum lighthouse between
Colachel and Cape Comorin,
India
Total length estimated from jaw
bone lengths of 5.56 m each,
lower jawbone at Travancore
Museum
Waite (1912) 8/2/1908 Female 26.5 -43.1333 170.2333 Near Commissioner’s Point,
10.5 km north of Okarito, New
Zealand
Length from tip of snout to notch
of tail, 30.2 m over curves of
back; skeleton at the
Canterbury Museum,
Christchurch (Stollman et al.,
2005)
Kinnear (1915) Jan 1911 21.3 16.9667 72.2833 Viziadrug, Ratnagiri District,
India
Measured from nose to tip of tail
in straight line, blue-black
baleen
Prater (1915) 11/12/1914 Male 12.5 16.8000 73.3167 Dhabool, 155 km south of
Bombay, India
Measured from tip of snout to tip
of flukes, ID uncertain
Reuter (1919) Dec 1916 27.28 -7.7000 107.7500 Pameungpeuk, between
Tjilauteureun and Tjikelet,
Java, Indonesia
Length from extremities of flukes
to tip of lower jaw, skeleton in
zoology museum in Bogor
R. M. Warneke, unpubl. 4/7/1923 Male 22.6 -38.6667 145.5833 ‘The wreck’, Wonthaggi, Victoria,
Australia
A. N. Baker, unpubl. 1/1/1925 Female 30 -36.5667 174.7167 Orewa, New Zealand
Waite (1926) 5/8/1925 7.42 -34.2500 138.2167 Head of Gulf St Vincent, South
Australia, Australia
Juvenile, carefully measured
Moses (1947) Nov 1927 28.7 9.9667 76.2333 Cherai, Cochin, India Skeleton at St. Aloysius College,
Mangalore, India
Rudolph et al. (1997) from
Delsman (1932)
Dec 1931 17 -7.2167 113.2333 Sampang, Madura Island,
Indonesia
De Silva (1987) from Pearson
(1932)*
26/5/1932 Male 8.5333 81.1500 Tamblegam Bay, Trincomalee, Sri
Lanka
164 T. A. Branch et al.
© 2007 The Authors. Journal compilation © 2007 Mammal Society, Mammal Review,37, 116–175
De Silva (1987) from Pearson
(1932)*
30/6/1932 20.1 8.4667 81.2167 Koddiyar Bay, Trincomalee, Sri
Lanka
Deraniyagala (1960) 6/2/1934 15.14 5.9333 80.5333 Polhena, Matara (S.P), Sri Lanka Described as fin whale but
uniform black colour and
all-black baleen; photo in De
Silva (1987)
Jones (1953) Jan/Feb
1934
21.6833 88.1667 Jambudwip, Bengal coast, India Decomposition advanced
McCann (1934) 7/5/1934 15.8 or
~21.3
18.9000 72.8000 Colaba Reclamation, Mumbai,
India
Exact location difficult to
determine
Deraniyagala (1965) 10/1/1939 ~19.5 6.0833 80.1333 Dodanduwa (S.P), Sri Lanka Length estimate uncertain
Moses (1940) 21/3/1939 Female 24.1 22.4000 68.9500 Mulvel, Okhamandel, India
Deraniyagala (1948) 23/1/1946 Female 18.3 8.5667 81.2167 Trincomalee Harbour, Sri Lanka Gave birth the next day in the
harbour, towed to safety
Deraniyagala (1960) 8/4/1949 6.8833 79.8500 Bambalapitiya (W.P.) Colombo,
Sri Lanka
Chari (1951) 14/5/1951 20.7 20.2000 72.7500 Umargam, 160 km from Bombay,
India
Decomposition advanced, 20.7 m
from tip of snout to centre of
flukes, some later sources
erroneously reported as 22.6 m
Wakefield (1967) Apr 1955 18 -38.4167 144. 1833Anglesea, 50 miles SW of
Melbourne, Victoria, Australia
Approximate length
Wakefield (1967) c. 1957 18.3 -38.2667 141.8500 Fitzroy River mouth, Portland
Bay, Victoria, Australia
Kewalramani (1969) 27/12/1960 Female 23.8 21.5333 72.6833 Soonvai Creek near village
Ganeshghan in Bhal area of
Vallabhipur Taluka, Bhavsagar
Dt., Gujarat, India
Location uncertain, some later
sources erroneously reported as
23.4 m on 7/12/1960
Daniel (1963) 23/2/1963 20.28 23.0667 72.7167 Village Gavier, near Magdalla
Port, 11 km from Surat,
Gujarat, India
Al-Robaae (1974) 6/6/1963 29.3333 48.1167 In muddy area, ‘Kadguma’,
Kuwait; location uncertain
Skeleton at Natural History
Museum, Shuaikh
Secondary School, Kuwait
Nagabhushanam & Dhulkhed
(1964)
21/4/1964 15.76 13.4167 74.6750 Muloor village, India Decomposition advanced, length
from tip of lower jaw to fluke
notch
Distribution of southern blue whales 165
© 2007 The Authors. Journal compilation © 2007 Mammal Society, Mammal Review,37, 116–175
Table A3. (Continued)
Source Date Sex Length (m) Latitude Longitude Position name Notes
Siddiqi (1968) 1965 25.2667 63.4833 Juddi near Pasni, Mekran coast,
Pakistan
Location of ‘Juddi’ not known,
lower jaw 3.0 m, skeleton in
Zoological Survey Museum,
Karachi, Pakistan
De Silva (1987) 3/4/1965 6.8833 79.8500 Wellawatte (W.P.), Sri Lanka
De Silva (1987) 14/4/1965 9.0000 80.9500 Kokkilai near Pulmoddai (E.P.),
Sri Lanka
James & Soundararajan (1979) 5/2/1966 13.65 9.2833 79.1167 Mandapam (Palk Bay), India Putrefied specimen
Venkataraman &
Girijavallabhan, 1966)
25/5/1996 13.51 11.2500 75.7667 Kannanparambu, 1 km south of
South Beach, Calicut, India
Calicut =Kozhikode, flipper:TL
1:8.6, baleen missing, ID
uncertain
R. M. Warneke, unpubl. 6/2/1967 18.3 -41.1167 146.1333 Three Sisters Island, Tasmania,
Australia
Approximate length
Siddiqi (1968) Jun 1967 18.3 25.2167 63.4000 5 miles west of Pasni, Makran
coast, Pakistan
Lower jaw 5.5 m, in Zoological
Survey Museum, Karachi,
Pakistan
Bensam, Vincent & Mahadevan
Pillai (1972)
2/4/1969 Female 11.26 8.7833 78.1667 Tuticorin, Gulf of Mannar, India Juvenile, alive but shot and killed
before brought to shore; ID
uncertain
IWC catch database, Bannister
et al. (2005)
May 1973 Female -35.0500 117.8833 Princess Royal Harbour, Albany,
Australia
Processed, yielded 118 barrels
Al-Robaae (1974) Unknown 23.61671 58.6000 Entangled in submarine telegraph
cable Muscat, Oman
Location named as Masket,
Arabia, in original
Bannister et al. (2005) May 1974 -35.0667 117.8667 Princess Royal Harbour, Albany,
WA, Australia
Cawthorn (1978) 1975 -39.1167 173.9500 Onetai Beach, Taranaki, New
Zealand
De Silva (1987) Mar 1976 Female 6.9333 79.8500 Galle Face, Colombo (W.P.), Sri
Lanka
Mother and calf
R. M. Warneke, unpubl. and
Leatherwood (1986)
5/4/1976 Male 17.5 -38.3833 142.0500 Levy’s Point, Victoria, Australia
Marichamy, Rajapandian &
Srinivasan (1984)
20/12/1976 Female 6.35 8.2667 77.9000 Near Ovari, Gulf of Mannar,
India
Immature female
166 T. A. Branch et al.
© 2007 The Authors. Journal compilation © 2007 Mammal Society, Mammal Review,37, 116–175
James & Soundararajan (1979) 4/10/1977 Female 10–12 9.2833 79.1833 Pamban, Palk Bay, India Entangled live in gillnet
A. N. Baker, unpubl. 30/4/1978 27.4 -36.5667 174.7167 Orewa, New Zealand
Leatherwood (1986) from
Fernando (1981)*
9/2/1981 7.5833 79.7833 Chilaw, Sri Lanka
Praderi (1985) 9/7/1983 18.3 -34.4333 -57.6000 Uruguay
Venkataramanujam, Paulraj &
Ramadhas (1984)
11/9/1983 11.67 8.2000 77.1667 Erayumanthurai near
Thengapattinam, Tamil Nadu,
India
Black baleen plates, advanced
decomposition
Anderson, Shaan & Waheed
(1999)
1984 19 7.0167 73.2500 H.A. Dhidhoo, floating at sea,
Maldives
Van Waerebeek et al. (1997) 24/2/1984 23 -36.6167 -72.9500 Coliumo Bay, near Tome, Chile
Anderson et al. (1999) 30/1/1985 22 3.5167 73.5667 V. Thinadhoo, floating off
V. Maadhiggaru, Maldives
Approximate length
Anderson et al. (1999) 16/2/1985 21 2.5000 73.3167 Th. Vilufushi, floating near reef,
rotten, Maldives
Approximate length
Somasekharan & Jayaprakash
(1987)
31/9/1985 Male 10.3 9.9667 76.2333 Chappa Beach, Narakkal, Cochin,
India
Date may be 31/8/1985; total
length 7.7 times flipper length,
identification uncertain.
A. D. Ilangakoon, unpubl. 11/7/1986 18.9 7.5807 79.8047 Chilaw (north-west coast) Sri
Lanka
Anonymous (1987b) 18/10/1986 13 10.9000 75.8833 Tirur beach, India Photograph provided
Smith et al. (1997) 19/1/1987 21.9 18.3333 94.3333 One mile from shore, Andrew Bay
(Thabyugyaing), Myanmar
(Burma)
Skeleton 17.4 m long, now in
Yangon Zoological Gardens
Rudolph et al. (1997) 22/6/1987 23.5 -3.2667 127.1167 Namlea, Buru Island, Indonesia Skeleton in Ambon Museum
Lal Mohan (1992) 29/9/1988 Female 19.2 12.1667 76.5000 Paravana, near Calicut, India Flippers 2.5 m, 1/7 total length;
80 throat grooves
Nammalwar et al. (1989) 10/12/1988 Male 15.16 16.9167 82.3167 Motupally, near
Ramachandrapuram, Andhra
Pradesh, Prakasam District,
India
Measured from tip of upper jaw
to notch of caudal fluke
C. Kemper, South Australian
Museum, pers. comm.
19/9/1989 Female -34.7300 138.5000 Gulf St. Vincent, Australia
R. M. Warneke, unpubl. 4/12/1991 Male 20 -39.9500 143.8500 British Admiral Beach, King
Island, Tasmania, Australia
Approximate length
A. N. Baker, unpubl. 1/3/1992 Female 16.4 -35.8167 174.5333 Whangarei harbour, New Zealand
Distribution of southern blue whales 167
© 2007 The Authors. Journal compilation © 2007 Mammal Society, Mammal Review,37, 116–175
Table A3. (Continued)
Source Date Sex Length (m) Latitude Longitude Position name Notes
Dalla Rosa & Secchi (1997) 29/4/1992 Female 23.1 -33.7500 -53.3800 2 km from Chui Bar southern
Brazil, near border with
Uruguay
Genetic sample held by L.
Pastene
Dixon & Frigo (1994) 5/5/1992 Male 18.17 -38.4833 144.0167 Cathedral Rock, 5 km NE of
Lorne, Victoria, Australia
Bannister et al. (2005) Mar 1993 -32.2000 115.6667 Garden Island, WA, Australia
James, Menon & Pillai (1993) 2/5/1993 26 9.9667 76.2333 Chellanam, Cochin, India Carcasse putrefied, length
approximate
LeDuc et al. (1997) 14/6/1993 -34.5167 135.3167 Australia
Van Waerebeek et al. (1997) 30/8/1993 12.5 3.6048 -77.2042 Periquillo beach, Colombia
Mohanraj, Somaraju & Seshagiri
Rao (1995)
9/5/1994 Male 11.73 17.8333 83.4167 Off Mangamaripeta, 12 km north
of Visakhapatnam, India
Live male caught in drift gillnet,
length from tip of upper jaw to
notch of caudal fluke, some
later sources erroneously list
date as 9/5/1995
A. N. Baker, unpubl. 11/9/1994 Male 20.6 -36.5667 175.0333 Hauraki Gulf, New Zealand Hit by ship, identified as pygmy
blue
Lipton et al. (1995) 25/11/1994 13.3 9.1833 79.4000 Dhanushkodi, India Measured from snout to notch of
caudal fluke
Van Waerebeek et al. (1997) 7/2/1995 Female 18 -33.9000 -71.8333 300 m north of mouth of Rapel
River, Chile
Decomposing
LeDuc et al. (1997) 9/5/1995 -36.9833 139.7000 Australia
Van Waerebeek et al. (1997) 3/1/1997 Female 20.44 -11.0393 -77.6597 Isla don Martin, Peru
R. C. Anderson, unpubl. 5/1/1997 16 3.2500 73.5000 V. Rakeedhoo, Maldives Floating at sea. Mandibles
(longest 482 cm) and scapula
on island
Anderson et al. (1999) 20/1/1997 18 2.2500 73.3000 Th. Guraidhoo, floating in
Veimandhoo Kandu, Maldives
Approximate length
Van Waerebeek et al. (1997) 20/3/1997 23 -41.1667 -73.9050 Near Llico Bajo, X Region, Chile
Anderson et al. (1999) 3/1/1999 19 6.2000 73.0333 Sh. Medukumburudhoo, washed
on beach, Maldives
168 T. A. Branch et al.
© 2007 The Authors. Journal compilation © 2007 Mammal Society, Mammal Review,37, 116–175
A. D. Ilangakoon, unpubl. 21/7/1999 Female 21.9–23.8 5.9612 80.4288 Kaparatota/Weligama (south
coast) Sri Lanka
McCauley et al. (2004) 6/11/2000 21 -13.7500 126.1330 Troughton Island, Kimberleys,
Australia
A. N. Baker, unpubl. 14/11/2001 Female 15.2 -34.6333 173.0167 Henderson Bay, New Zealand Pygmy blue?
McCauley et al. (2004), K. C. S.
Jenner, unpubl.
9/12/2001 22.3 -34.0881 114.9989 Cape Freycinet, Western
Australia, Australia
ID as pygmy blue whale; location
incorrectly reported as
Margaret River
Borsa & Hoarau (2004), Borsa
(2006)
29/1/2002 Male 16.5 -22.3333 166.8167 Baie de la Somme, New
Caledonia
R. C. Anderson, unpubl. 9/12/2002 15 4.1667 73.5167 SW outer reef, K. Malé, Maldives Rotten, most of head missing,
vertebral
epiphyses not fully fused
Krishnan et al. (2004) 21/12/2001 12.3 13.3000 74.7000 Beach of Guijerbettu, Udupi
district, Karnataka, India
Dorsal fin 1% of total length
A. D. Ilangakoon, unpubl. 15/10/2003 Female 20.1 6.9103 79.8492 Bambalapitiya/Colombo (west
coast) Sri Lanka
A. D. Ilangakoon, unpubl. 2/4/2004 Male 19.8–21.3 6.9418 79.8597 Colombo Harbor (west coast) Sri
Lanka
A. D. Ilangakoon, unpubl. 11/7/2004 18 8.1377 79.7005 Thalawila (north-west coast) Sri
Lanka
R. C. Anderson, unpubl. 6/1/2005 23 4.2500 73.5500 On outer reef, K. Furana,
Maldives
Rotten, tail and part of head
missing, photos held at MRC
Hucke-Gaete et al. (2005);
B. Galletti Vernazzani, unpubl.
29/3/2005 Male 23 or 24.38 -41.9861 -74.0333 Pumillahue Bay, NW Chiloé
Island, Chile
Bannister et al. (2005) 16/12/2005 Female 20.8 -32.0167 115.4686 Strickland Bay, Rottnest Island,
Western Australia
Tail-anus/total length =0.24,
therefore likely a pygmy blue
whale
R. C. Anderson, unpubl. 19/12/2005 20 4.6833 73.4333 K. Olhahahi, Maldives Photos held at MRC
*Details of original reference have not been obtained or were not listed in citing paper.
Distribution of southern blue whales 169
© 2007 The Authors. Journal compilation © 2007 Mammal Society, Mammal Review,37, 116–175
APPENDIX 4
Details of blue whales marked and recaptured in the Southern Hemisphere, ordered by Discovery tag number. When two marks were recovered from
one whale, they were both fired on the same day and at the same location, except for two instances detailed in the footnotes. Where the notes indicate
‘uncertain’, and probably in instances where length and sex were not recorded, the mark was recovered from the cooker, digester, boiler or stored
meat. In such cases, a range of possible recapture locations and dates was often recorded and the central such position and date reported here. Code
prefix ‘G’ indicates a German mark and ‘USSR’ a Soviet mark.
Code
Marked
latitude
Marked
longitude
Marked
date
Recaptured
latitude
Recaptured
longitude
Recaptured
date Sex
Length at
capture (m)
Distance
(km)
Duration
(days) Notes
656/1229* -54.7167 -33.9833 26/12/1934 -54.5000 -34.3167 29/12/1934 Female 24.1 32 3
700 -54.2500 -33.9667 06/12/1934 -54.1833 -34.8333 11/12/1934 Male 23.8 57 5
825/853 -54.9167 -35.2333 30/11/1934 -55.1333 -34.5333 30/11/1934 Male 23.5 51 0
859 -54.9000 -35.2333 30/12/1934 -54.5000 -37.0000 28/11/1946 122 4351
903 -54.0167 -38.8500 12/01/1935 -55.4000 -33.7833 19/01/1935 Female 23.9 360 7
1123/1125 -55.0000 -34.3333 29/12/1934 -62.3333 -45.8333 12/01/1939 Female 25.3 1048 1475
1245 -54.8833 -34.5667 27/12/1934 -59.3833 -9.3667 30/12/1939 1589 1829
2026 -57.4333 23.8333 14/12/1935 -61.0000 87.0000 16/12/1936 3473 368
2525 -56.6667 39.0000 05/12/1934 -64.5500 22.8333 01/02/1937 Female 22.9 1236 789
2537 -56.6000 35.7500 04/12/1934 -57.6167 16.4667 22/12/1938 Female 25.5 1165 1479
2548 -58.3500 49.2667 08/12/1934 -59.0000 34.2500 02/12/1937 Male 24.4 869 1090
2816 -63.3500 53.5333 17/01/1935 -64.0000 90.0000 09/03/1936 1774 417
2892 -63.5333 47.2833 22/01/1935 -65.2833 84.5000 26/02/1936 Male 25.9 1770 400
2902 -63.5333 47.9500 22/01/1935 -66.0000 15.0000 12/03/1935 1566 49
2903 -63.5333 47.9500 22/01/1935 -63.9333 45.9333 26/01/1935 Male 26.2 109 4
2910 -62.7500 46.3667 24/01/1935 -63.4167 45.9333 26/01/1935 Female 21 77 2
2960/2965 -62.7667 43.0833 26/01/1935 -64.7667 41.4167 31/01/1935 Female 22.1 237 5
2963 -62.6500 43.9667 26/01/1935 -62.6500 34.8833 08/02/1935 Female 25.9 463 13
3013 -61.9167 43.2833 28/01/1935 -64.2333 29.7500 27/03/1935 Female 22.9 726 58
170 T. A. Branch et al.
© 2007 The Authors. Journal compilation © 2007 Mammal Society, Mammal Review,37, 116–175
3023 -62.0167 43.3500 28/01/1935 -63.6167 39.9000 09/01/1936 250 346
3528 -63.4333 26.1833 28/02/1935 -64.4500 79.4500 17/01/1937 Female 22.6 2526 689
3598 -63.3833 8.3000 08/03/1935 -60.0000 32.0000 20/01/1948 1296 4701
3771 -54.1833 -39.2500 04/12/1935 -54.8667 -32.6833 14/11/1936 Male 24.2 430 346
3853 -56.1333 -36.0167 11/12/1935 -63.3667 -47.1167 07/03/1936 Female 22.6 1013 87
4122 -57.2833 -33.9167 27/12/1935 -54.5667 -33.7000 30/12/1935 302 3
4563 -55.3167 -36.6500 02/01/1936 -59.7333 -29.7667 02/02/1936 Male 22.9 639 31
4843 -54.8667 -33.7333 18/01/1936 -55.2333 -34.2500 22/01/1936 52 4
5245 -62.1333 87.6167 01/02/1936 -63.9167 87.4667 08/02/1936 Female 26.8 198 7
5261 -61.9333 88.7000 01/02/1936 -61.8667 82.9500 02/01/1938 Female 25.9 301 701
5456 -63.9500 99.3167 13/02/1936 -56.6333 12.3500 09/01/1948 Female 27.7 4474 4348 Pregnant
5525 -63.2500 94.3167 16/02/1936 -63.7333 94.4167 17/02/1936 Female 25.3 54 1
5632 -63.7500 81.8500 22/02/1936 -57.3833 31.6667 20/12/1947 Female 2751 4319 Pregnant
5728 -63.8167 54.4000 02/03/1936 -56.8000 17.0333 08/01/1937 2161 312
5800 -64.4000 45.8167 08/03/1936 -63.2333 72.3667 03/01/1938 Female 23.5 1299 666
7705 -54.9000 24.8167 13/12/1936 -61.1167 20.8333 09/02/1937 Female 24.4 729 58
8743 -64.8667 30.7000 13/02/1937 -55.5000 27.5000 15/12/1947 1055 3957 Uncertain
10427/10431 -55.8167 -0.2333 17/12/1937 -55.2000 -35.4000 24/02/1939 Female 22.1 2190 434
10638 -58.8000 -31.3667 01/01/1938 -61.2500 -20.3500 09/01/1938 Male 22.9 668 8
11354 -61.5000 54.8333 07/01/1953 -68.6333 17.2833 18/03/1954 1890 435
12186 -56.4667 -6.9500 29/11/1953 -54.5000 -37.0000 23/03/1954 1889 114
12362 -57.3667 -32.6000 23/12/1953 -60.0000 -41.0000 20/01/1954 566 28 Uncertain
12363 -57.6333 -32.7000 23/12/1953 -61.3000 -31.4333 16/02/1954 Male 23.2 414 55
12391 -59.8833 -37.2500 10/12/1953 -68.3333 -15.5000 12/03/1954 Male 23.2 1399 92
12438 -53.9167 8.6667 29/11/1954 -62.1000 -12.0000 21/02/1956 1508 449
12770 -58.7833 42.2500 03/11/1955 -65.1833 82.3667 03/03/1957 Female 24.1 2168 486
12777 -57.7667 39.9167 04/11/1955 -69.2167 17.0000 09/03/1957 1686 491 Uncertain
12826 -54.4000 24.5667 10/11/1955 -69.0000 4.0000 14/02/1957 1930 462 Uncertain
13147 -62.9500 -38.0333 16/11/1955 -65.0500 -26.8667 18/02/1956 591 94
13400 -60.3167 55.2000 02/12/1957 -64.4000 48.8167 03/02/1959 Female 24.7 560 428
Distribution of southern blue whales 171
© 2007 The Authors. Journal compilation © 2007 Mammal Society, Mammal Review,37, 116–175
Table A4. (Continued)
Code
Marked
latitude
Marked
longitude
Marked
date
Recaptured
latitude
Recaptured
longitude
Recaptured
date Sex
Length at
capture (m)
Distance
(km)
Duration
(days) Notes
14645 -64.5000 -157.6833 05/01/1956 -68.2833 -125.8833 07/02/1958 Male 23.2 1458 764 Uncertain
14661 -62.7667 -127.0833 09/12/1955 -66.2667 -148.1167 17/02/1957 Female 22.9 1072 436 CL 0 EP 7
14730 -62.7833 60.0000 17/12/1955 -67.4000 -127.4167 22/02/1958 Male 22.3 5523 798
15216 -59.4000 41.2167 02/11/1955 -61.6167 -8.1500 17/02/1956 Male 21.3 2646 107
17406 -60.2500 139.0000 01/01/1957 -70.7167 161.1333 12/03/1959 Female 21.3 1529 800
17629 -67.3000 -82.3333 22/12/1956 -67.7333 -89.9833 02/02/1957 Female 23.5 328 42
17644 -65.7000 -85.3333 23/12/1956 -66.3333 -122.4167 02/02/1957 Female 23.2 1652 41 CL 0 EP 7
17645 -65.4667 -87.8333 23/12/1956 -72.3333 -156.0000 18/02/1958 2665 422
17745 -66.6500 -89.0667 03/01/1957 -66.2000 -95.7833 01/02/1957 Male 25 303 29
17866 -65.8500 -92.6333 20/12/1956 -66.0000 -95.0000 01/02/1957 Male 24.7 109 43
18027 -65.2000 -179.3167 02/12/1957 -65.8667 48.5667 22/03/1962 4943 1571 Uncertain
18085 -64.8833 -164.0667 04/12/1957 -67.1667 168.5833 14/02/1959 Female 25.6 1250 437 CL 19
18155/
18194†
-65.5500 -80.8000 23/12/1957 -69.0167 -132.4000 08/02/1958 Female 21.9 2179 47
18163 -65.5500 -80.8000 23/12/1957 -57.9000 87.7500 27/02/1962 Male 24.1 6250 1527 EP 12
18166 -65.4333 -81.0000 23/12/1957 -69.0000 -96.6333 23/02/1958 Male 22.3 778 62
18235 -65.8833 -73.8667 02/01/1957 -67.5000 -128.3333 09/02/1957 2324 38
18318 -64.2667 155.7333 30/12/1957 -63.7667 85.0667 12/02/1959 Male 21.9 3262 409
18323 -64.0333 156.0333 30/12/1957 -67.6167 162.9167 09/02/1958 Male 22.9 506 41
18981 -61.0833 -56.3333 20/12/1956 -67.3167 -132.7833 04/02/1957 Female 21.6 3516 46 CL 0
19705/19719 -60.2333 60.1667 21/12/1957 -63.5000 99.5000 15/02/1958 Female 20.7 2058 56
19720/19728 -60.9500 57.8333 21/12/1957 -61.5167 70.0000 05/02/1959 Male 23.5 653 411
19754 -61.3167 54.8333 22/12/1957 -64.2333 16.7667 02/02/1958 Female 1932 42
19762 -60.8667 54.5000 24/12/1957 -66.0000 40.0000 15/02/1959 915 418
19766 -60.9000 51.3667 23/12/1957 -64.7500 -15.7500 25/02/1958 3270 64 Uncertain
172 T. A. Branch et al.
© 2007 The Authors. Journal compilation © 2007 Mammal Society, Mammal Review,37, 116–175
19768 -60.8667 54.5000 24/12/1957 -63.1167 94.4833 13/02/1958 Male 21.9 2067 51
19772 -60.8500 54.4667 24/12/1957 -62.5000 84.5000 15/02/1958 1579 53 Uncertain
19792 -60.9833 55.2667 24/12/1957 -64.8500 19.8000 06/02/1958 Female 21.3 1819 44
19798 -61.3167 55.6333 24/12/1957 -62.5000 84.5000 15/02/1958 1503 53 Uncertain
19799 -60.9833 55.4000 24/12/1957 -55.0833 35.3500 20/03/1962 1342 1547
19834 -67.3000 171.1333 15/12/1957 -64.5000 136.0000 20/02/1959 Male 22.9 1601 432
20512 -65.2000 157.0833 19/12/1958 -65.6667 139.8333 08/02/1959 Male 23.8 796 51
20515 -65.2333 157.0333 19/12/1958 -64.4167 123.5000 13/02/1959 Female 23.8 1569 56 EP 7
22321 -63.0667 137.0167 16/12/1959 -57.3333 95.6667 04/02/1960 Male 22.9 2325 50 EP 11
22543 -59.3333 83.7667 22/12/1959 -58.8500 73.5333 04/02/1960 Male 21.9 586 44 EP 11
24027 -55.7667 80.2167 15/12/1960 -60.8500 38.9167 >05/03/1962 2432 >445 ‘1961/62’
24535 -58.9667 38.6000 19/12/1960 -67.1333 -3.5833 21/02/1961 Female 24.7 2254 64
25576 -56.2500 49.0500 01/12/1962 -43.9167 50.0333 04/04/1963 Male 21.5 1372 124 Pygmy,
testes
16.0 kg,
14.5 kg
25605/25607 -59.3833 66.7667 23/11/1962 -54.5833 36.4333 05/03/1964 Female 24.2 1894 468 CL0EP10
G01111 -63.0000 25.7500 18/02/1939 -63.8333 33.6667 12/01/1940 Male 19.5 404 328
G01201 -59.0000 30.0000 07/12/1938 -64.9000 62.3833 02/01/1951 Female 27.4 1790 4409 Pregnant
G01305 -60.8333 31.8333 31/12/1938 -60.4000 30.5167 02/01/1939 86 2
G01306 -65.0000 35.0000 09/02/1939 -65.4500 28.1500 06/03/1939 323 25
G01309 -59.4167 33.8333 06/12/1938 -61.4000 36.9000 20/12/1938 Female 25.3 277 14
G01370 -65.2333 35.0000 26/02/1939 -65.4500 28.4833 06/03/1939 303 8
USSR-25601 -59.3833 66.7667 23/11/1962 -63.5000 26.0833 02/01/1967 Male 2170 1501
USSR-25608 -59.3833 66.7667 23/11/1962 -63.6167 26.1667 02/01/1967 Female 2164 1501
USSR-25619 -59.1333 68.3333 23/11/1962 -59.6000 54.3667 10/01/1963 Female 791 48
*Mark latitude of 1229 was -54.6500.
†Mark longitude of 18194 was -80.8333.
CL, corpora lutea count; EP, ear plug laminae.
Distribution of southern blue whales 173
© 2007 The Authors. Journal compilation © 2007 Mammal Society, Mammal Review,37, 116–175
APPENDIX 5
List of sources for acoustic detections of blue whales in the study region. The reference, region (positions rounded to whole degrees), call type,
recording method and dates are listed. Where sources are ‘unpubl.’ this is shorthand for ‘unpublished data’.
Source Region Call type Recording method Recording duration Dates calls recorded
Alling et al. (1991) East coast, Sri Lanka Sri Lanka Dipping hydrophone Feb–Apr 1984 Feb–Apr 1984
C. W. Clark & A. R. Martin,
pers. comm.
South Georgia 54°S 38°W Antarctic Moored instrument 4–5 Apr 2004 4–5 Apr 2004
Cummings & Thompson
(1971)
Guafo Island, Chile South-east Pacific Dipping hydrophone 30–31 May 1970 30–31 May 1970
Ensor et al. (1999),
Clark & Fowler (2001)
Antarctica Areas III, IV Antarctic Sonobuoy Jan–Feb 1999 10, 15, 25 Jan; 4, 9, 21 Feb
1999
Ensor et al. (2000),
D. Ljungblad, unpubl.
Antarctica Area I 67–71°W Antarctic Sonobuoy Jan–Feb 2000 26 Jan; 11 Feb 2000
Ensor et al. (2004) Antarctica Area V
175°W-175°E
Antarctic Sonobuoy Jan–Feb 2004 19 Jan; 7–21 Feb 2004
Ensor et al. (2006) Antarctica Area III 0–20°E Antarctic Sonobuoy 18 Jan-13 Feb 2006 18 Jan-13 Feb 2006
Kibblewhite et al. (1967) Three Kings Island, New
Zealand
New Zealand Moored instrument 1 day; date unknown Unknown
Ljungblad et al. (1998) Antarctic area II Antarctic Sonobuoy 7 Jan-26 Feb 1997 29–30 Jan 1997
Ljungblad et al. (1998) Madagascar Plateau 25–35°S
40–45°E
Madagascar Sonobuoy 7–28 Dec 1996 28 Dec 1996
McCauley et al. (2004) Cape Leeuwin, Australia Antarctic Moored instrument Oct 2002–Jul 2004 May–Oct 2002-04
McCauley et al. (2004) Cape Leeuwin, Australia Australian Moored instrument Oct 2002–Jul 2004 Nov–Jun 2002-04
R. D. McCauley, unpubl. Bass Strait 40°S 145°E New Zealand Moored instrument Mar–Aug 2002 Jun 2002
R. D. McCauley, unpubl. Bass Strait 40°S 145°E Australian Moored instrument Mar–Aug 2002 Jun 2002
R. D. McCauley, unpubl. Robe, South Australia 37°S
140°E
Australian Moored instrument Nov 2004–Jun 2005; Nov
2005–Jun 2006
Jan–Apr 2005-06
R. D. McCauley, unpubl. Perth Canyon, Australia 32°S
115°E
Australian Moored instrument Jan 2000–Dec 2005 Nov–Jun, 2000-05
R. D. McCauley, unpubl. Exmouth, Australia 21°S
114°E
Australian Moored instrument Oct 2003–Oct 2004 Nov–Dec 2003, Jun 2004
McKay et al. (2005) East Antarctica 67°S 70°E Antarctic Moored instrument Feb 2003–Jan 2004 Year-round but peaks
Apr–Jun, Nov
McDonald (2006) North Island, New Zealand Antarctic Moored instrument Jan–Dec 1997 May–Jul 1997
174 T. A. Branch et al.
© 2007 The Authors. Journal compilation © 2007 Mammal Society, Mammal Review,37, 116–175
McDonald (2006) North Island, New Zealand New Zealand Moored instrument Jan–Dec 1997 Once each in Jun, Jul,
Sep, Dec 1997
T. F. Norris, unpubl. Islas Lobos De La Fuera,
Peru
South-east Pacific Sonobuoy 2–3 Nov 2000 2–3 Nov 2000
Rankin et al. (2005) Antarctic area V
150°E-170°W
Antarctic Sonobuoy 6–8, 21, 29, 31 Jan 2002 6–8, 21, 29, 31 Jan 2002
Rankin et al. (2005) Antarctic area V
130°E-150°E
Antarctic Sonobuoy 23–24 Jan 2003 23–24 Jan 2003
Samaran et al. (2006) Crozet Island Antarctic Moored instrument May 2003–Apr 2004 Unknown
Samaran et al. (2006) Crozet Island Madagascar Moored instrument May 2003–Apr 2004 Unknown
Širovic´ et al. (2004) Western Antarctic Peninsula Antarctic Moored array Mar 2001–Feb 2003 Year-round but peaks
Mar–Apr, Oct–Nov
Stafford et al. (1999) Eastern tropical Pacific 8°S
95°W
South-east Pacific Moored instrument May 1996–May 1997 Year-round but peaks
Mar–Aug
Stafford et al. (1999) Eastern tropical Pacific 8°S
95°W
Antarctic Moored instrument May 1996–May 1997 Jul 1996
Stafford et al. (2004) Eastern tropical Pacific 8°S
95°W
Antarctic Moored instrument May 1996–Nov 2002 Jun–Sep, peaks in Jul
Stafford et al. (2004) Indian Ocean Diego Garcia Antarctic Moored instrument Jan 2002–Apr 2003 May–Aug, peaks in Jul
Stafford et al. (2004) Indian Ocean Cape Leeuwin Antarctic Moored instrument Jan 2002–Apr 2003 May–Nov, peaks in Jul
Stafford et al. (2005) Indian Ocean Diego Garcia Madagascar Moored instrument Jan 2002–Apr 2003 May–Jul, peak in Jul
Stafford et al. (2005) Indian Ocean Diego Garcia Sri Lanka Moored instrument Jan 2002–Apr 2003 May–Jan
Stafford et al. (2005) Indian Ocean Cape Leeuwin Australia Moored instrument Jan 2002–Apr 2003 Dec–Jun
Distribution of southern blue whales 175
© 2007 The Authors. Journal compilation © 2007 Mammal Society, Mammal Review,37, 116–175
... Many baleen whale species and populations are endangered, following the 20 th century industrial whaling. For instance, as the largest animals in the world, blue whales (Balaenoptera musculus) were targeted by whalers, with only 0.15% of the Southern Hemisphere population surviving commercial whaling (Branch et al., 2007;Thomas et al., 2016). Large baleen whales such as blue whales have few natural predators and feed on prey at low trophic levels, occupying a rare niche with few other species. ...
... Thus, if global change that leads to their loss occurs, it is unlikely that they could be easily replaced within the food web. Furthermore, their longdistance migration behaviour requires considerable energy (Branch et al., 2007). Thus, large baleen whales require predictable and high-energy food sources for the few months they feed. ...
... Mean chlorophyll-a was calculated for each year and both seasons (December to May; June to November). One potential caveat is that the measurement of the chlorophylla was from the water surface, hence the data may not reflect krill density in deep water (Branch et al., 2007). ...
Article
Full-text available
Marine ecosystems are experiencing rapid shifts under climate change scenarios and baleen whales are vulnerable to environmental change, although not all impacts are yet clear. We identify how the migration behaviour of the Chagos whale, likely a pygmy blue whale (Balaenoptera musculus brevicauda), has changed in association with shifts in environmental factors. We used up to 18 years of continuous underwater acoustic recordings to analyse the relationships between whale acoustic presence and sea surface temperature (SST), chlorophyll-a concentration, El-Niño Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD). We compared these relationships between two independent sites Diego Garcia southeast (DGS) and Diego Garcia northwest (DGN) where Chagos whales are detected and are suspected to move interannually across the Chagos-Laccadive ridge. We showed that the number of whale songs detected increased on average by 7.7% and 12.6% annually at DGS and DGN respectively. At the DGS site, Chagos whales shifted their arrival time earlier by 4.2 ± 2.0 days/year ± SE and were detected for a longer period by 7.3 ± 1.2 days/year ± SE across 18 years. A larger number of songs were detected during periods of higher chlorophyll-a concentration, and with positive IOD phases. At the DGN site, we did not see an earlier shift in arrival and songs were not detected for a longer period across the 13 years. Whale presence at DGN had a weaker but opposite relationship with chlorophyll-a and IOD. The oceanic conditions in the Indian Ocean are predicted to change under future climate scenarios and this will likely influence Chagos whale migratory behaviour. Understanding how environmental factors influence whale movement patterns can help predict how whales may respond to future environmental change. We demonstrate the value of long-term acoustic monitoring of marine fauna to determine how they may be affected by changing environmental conditions.
... During this migration the species also uses other transitory areas to feed, such the Frontal System off Baja California [20]. Blue whales from the Southern Hemisphere forage in the southern Humboldt Current System and the Antarctic Circumpolar Current in summerautumn [21]. Some of them migrate in winter-spring to the northern Humboldt Current System [21,22], and the Equatorial Cold Tongue [23] for breeding. ...
... Blue whales from the Southern Hemisphere forage in the southern Humboldt Current System and the Antarctic Circumpolar Current in summerautumn [21]. Some of them migrate in winter-spring to the northern Humboldt Current System [21,22], and the Equatorial Cold Tongue [23] for breeding. Although blue whales have been recorded year-round at the Costa Rica Dome, it is not clear whether those animals come from both hemispheres, or if at least some belong to a resident population [24]. ...
... They migrate to mid and low latitudes during the summer-autumn of the Northern Hemisphere (i.e. winter-spring of the Southern Hemisphere) to reproduce and feed [21]. Therefore, we would expect that the higher whale densities during this period are concentrated in the South Equatorial Countercurrent and the northern Humboldt Current System, where higher temperatures would be more suitable for calving and where prey aggregations remain high. ...
Article
Full-text available
We inferred the population densities of blue whales (Balaenoptera musculus) and short-beaked common dolphins (Delphinus delphis) in the Northeast Pacific Ocean as functions of the water-column’s physical structure by implementing hierarchical models in a Bayesian framework. This approach allowed us to propagate the uncertainty of the field observations into the inference of species-habitat relationships and to generate spatially explicit population density predictions with reduced effects of sampling heterogeneity. Our hypothesis was that the large-scale spatial distributions of these two cetacean species respond primarily to ecological processes resulting from shoaling and outcropping of the pycnocline in regions of wind-forced upwelling and eddy-like circulation. Physically, these processes affect the thermodynamic balance of the water column, decreasing its volume and thus the height of the absolute dynamic topography (ADT). Biologically, they lead to elevated primary productivity and persistent aggregation of low-trophic-level prey. Unlike other remotely sensed variables, ADT provides information about the structure of the entire water column and it is also routinely measured at high spatial-temporal resolution by satellite altimeters with uniform global coverage. Our models provide spatially explicit population density predictions for both species, even in areas where the pycnocline shoals but does not outcrop (e.g. the Costa Rica Dome and the North Equatorial Countercurrent thermocline ridge). Interannual variations in distribution during El Niño anomalies suggest that the population density of both species decreases dramatically in the Equatorial Cold Tongue and the Costa Rica Dome, and that their distributions retract to particular areas that remain productive, such as the more oceanic waters in the central California Current System, the northern Gulf of California, the North Equatorial Countercurrent thermocline ridge, and the more southern portion of the Humboldt Current System. We posit that such reductions in available foraging habitats during climatic disturbances could incur high energetic costs on these populations, ultimately affecting individual fitness and survival.
... Antarctic blue whales primarily filter feed on zooplankton prey, chiefly Antarctic krill (Euphausia superba) (Best, 2007; Branch et al., 2007). Little or no feeding is thought to occur during winter migrations and their distribution during the austral summer is particularly determined by prey distribution (Best, 2007; Branch et al., 2007). ...
... Antarctic blue whales primarily filter feed on zooplankton prey, chiefly Antarctic krill (Euphausia superba) (Best, 2007; Branch et al., 2007). Little or no feeding is thought to occur during winter migrations and their distribution during the austral summer is particularly determined by prey distribution (Best, 2007; Branch et al., 2007). Year-round passive acoustic recordings show that Antarctic blue whales might be feeding on their breeding grounds and move in between regions in a season, possibly to make use of available food resources in those regions (Samaran et al., 2013). ...
... Figure 1: Multi-decadal patterns of catches (a) and abundance estimated by logistic models (b) of the Antarctic blue whale in the southern hemisphere showing the discovery, exploitation and subsequent collapse of the species (adapted from Branch et al., 2004). It is currently difficult from sighting surveys to monitor the population recovery of the Antarctic blue whale, which was so extensively decimated by commercial whaling (Branch et al., 2007). The difficulty with sighting surveys is that trained observers can only see Antarctic blue whales for a short period of time when these mammals surface to breathe, and those sighting surveys can only be done in adequate daylight during good weather conditions (Mellinger and Barlow, 2003; Thomas and Marques, 2012). ...
Chapter
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Marine mammals, and in particular Antarctic blue whales, represent an important predator component of marine ecosystems. These mammals are considered to be critically endangered due to unsustainable whaling practices in the previous century. Currently, it is also difficult to monitor the species’ population recovery through the use of sighting surveys. Passive acoustic monitoring (PAM) can be used to research Antarctic blue whales because they are quite vocal and can be detected over long distances through the use of this technology. PAM also has considerable application potential to other baleen species that reside in South African waters, including fin whales (Balaenoptera physalus). It is, however, still an emerging methodology in South Africa and a number of challenges need to be addressed before it reaches the same level of maturity as visual surveys in South Africa and around the world.
... In many mammalian species, including elephants [102], pinnipeds [103] and ungulates [104][105][106][107], the limitation or cessation of food consumption by males during the breeding season is common-the motivation for which appears to be the reduction of foraging time in favour of breeding efforts. While it has previously been accepted that both sexes of several baleen whale species also limit food intake during their annual migrations to breeding grounds [89], blue whales may exhibit both foraging and reproductive behaviours on their low-latitude breeding grounds [108,109]. Therefore, it is also possible that multiple behavioural states may also be exhibited at feeding sites. Although southern California is primarily considered to be a seasonal feeding ground for blue whales, our analysis indicates a temporal separation between two behavioural states for blue whales in this region: individuals may begin feeding as early as spring, continuing through summer until the autumn, at which time reproductive behaviours begin to dominate. ...
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Acoustic communication is an important aspect of reproductive, foraging and social behaviours for many marine species. Northeast Pacific blue whales (Balaenoptera musculus) produce three different call types—A, B and D calls. All may be produced as singular calls, but A and B calls also occur in phrases to form songs. To evaluate the behavioural context of singular call and phrase production in blue whales, the acoustic and dive profile data from tags deployed on individuals off southern California were assessed using generalized estimating equations. Only 22% of all deployments contained sounds attributed to the tagged animal. A larger proportion of tagged animals were female (47%) than male (13%), with 40% of unknown sex. Fifty per cent of tags deployed on males contained sounds attributed to the tagged whale, while only a few (5%) deployed on females did. Most calls were produced at shallow depths (less than 30 m). Repetitive phrasing (singing) and production of singular calls were most common during shallow, non-lunging dives, with the latter also common during surface behaviour. Higher sound production rates occurred during autumn than summer and they varied with time-of-day: singular call rates were higher at dawn and dusk, while phrase production rates were highest at dusk and night.
... Of global interest are habitats important to pygmy blue whales (Balaenoptera musculus brevicauda), a subspecies that has not fully recovered from exploitation and still faces threats, such as ship strikes, incidental catch and oil and gas development (Clapham et al., 1999;CSIRO, 2007;Tournadre, 2014). Based off historic catch distributions (Branch et al., 2007) and, more recently, by satellite tag tracking data (Gales et al., 2010;Double et al., 2014), pygmy blue whales are indicated to be in the vicinity of the Browse Basin. Understanding the distribution of pygmy blue whales and other cetaceans in the Browse Basin is needed given their important role in impacting marine ecosystems, e.g. ...
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There is an increasing demand for integrated pelagic surveys to support ecosystem-based management of marine environments and their associated marine life. The Browse Basin in the tropical eastern Indian Ocean was surveyed using ship line transects to determine habitat associations of cetaceans and seabirds with submarine topography and local oceanographic conditions during winter and spring 2008. Fourteen species of cetaceans, including the data deficient pygmy blue whale, and 23 species of seabirds were encountered throughout the basin. Aggregations of both cetaceans and seabirds were observed at two significant submarine topographic features, Scott Reef and Browse Cliffs, particularly during spring when encounters and abundances of odontocetes were far greater. The attraction of cetaceans and seabirds to Scott Reef and Browse Cliffs was likely foraging-related given these features were associated with upwelling and elevated biomass of krill and fish. Sub-mesoscale sea surface temperature and chlorophyll a fronts also occurred in vicinity to Browse Cliffs and the shelf environment. The Browse Basin is an important, and potentially predictable, foraging ground for a variety of top predators, and their occurrence would have implications for the current and future management practices of oil and gas industries operating in the region.
... A number of their areas of aggregation have been identified, including waters near Somalia ( Small and Small, 1991), the Seychelles ( Mikhalev, 2000), the Maldives ( Ballance et al., 2001;Anderson, 2005), and Sri Lanka (de Vos et al., 2014a). Sighting, stranding and acoustic data ( Alling et al., 1991;Ilangakoon, 2006;Branch et al., 2007;Afsal et al., 2008;de Vos et al., 2012) indicate that this population occupies Sri Lankan waters almost year round. Off southern Sri Lanka, groups of NIO blue whales have been observed engaging in breeding activity (specifically "ménage à trois" behaviors as described by Sears et al., 2009). ...
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Blue whales are little studied, face significant anthropogenic threats and within the Northern Indian Ocean, have a restricted range, making them an archetype for conservation needs of megafauna around the world. We studied feeding behavior of blue whales using dietary DNA metabarcoding of fecal samples. While globally blue whale populations feed predominantly on Euphausiidae, 87% of prey DNA amplicons extracted from fecal samples from this population were sergestid shrimp, demonstrating that blue whales can locate and feed on dense swarms of other types of prey when they occur. Within the Indian Ocean sergestids are present within the top 300 m, which correlates with the deep scattering layer observed by hydroacoustics. Studies suggest that this requirement to dive deeper in search of prey likely explains the prevalence of fluke up diving within this population of blue whales relative to other parts of the globe. Furthermore, this study revealed the presence of acanthocephalan endoparasites within the stomach and intestines of the Northern Indian Ocean blue whales. This represents the first record of Acanthocephala in blue whales in the Northern Indian Ocean and highlights the need for further studies on both the ecto- and endoparasitic flora and monitoring of health of these cetaceans for their management and conservation.
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The study of marine soundscapes is a growing field of research. Recording hardware is becoming more accessible; there are a number of off-the-shelf autonomous recorders that can be deployed for months at a time; software analysis tools exist as shareware; raw or preprocessed recordings are freely and publicly available. However, what is missing are catalogues of commonly recorded sounds. Sounds related to geophysical events (e.g. earthquakes) and weather (e.g. wind and precipitation), to human activities (e.g. ships) and to marine animals (e.g. crustaceans, fish and marine mammals) commonly occur. Marine mammals are distributed throughout Australia’s oceans and significantly contribute to the underwater soundscape. However, due to a lack of concurrent visual and passive acoustic observations, it is often not known which species produces which sounds. To aid in the analysis of Australian and Antarctic marine soundscape recordings, a literature review of the sounds made by marine mammals was undertaken. Frequency, duration and source level measurements are summarised and tabulated. In addition to the literature review, new marine mammal data are presented and include recordings from Australia of Omura’s whales (Balaenoptera omurai), dwarf sperm whales (Kogia sima), common dolphins (Delphinus delphis), short-finned pilot whales (Globicephala macrorhynchus), long-finned pilot whales (G. melas), Fraser’s dolphins (Lagenodelphis hosei), false killer whales (Pseudorca crassidens), striped dolphins (Stenella coeruleoalba) and spinner dolphins (S. longirostris), as well as the whistles and burst-pulse sounds of Australian pygmy killer whales (Feresa attenuata). To date, this is the most comprehensive acoustic summary for marine mammal species in Australian waters.
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We examined recordings from a 15-month (May 2009–July 2010) continuous acoustic data set collected from a bottom-mounted passive acoustic recorder at a sample frequency of 6 kHz off Portland, Victoria, Australia (38°33′01″S, 141°15′13″E) off southern Australia. Analysis revealed that calls from both subspecies were recorded at this site, and general additive modeling revealed that the number of calls varied significantly across seasons. Antarctic blue whales were detected more frequently from July to October 2009 and June to July 2010, corresponding to the suspected breeding season, while Australian blue whales were recorded more frequently from March to June 2010, coinciding with the feeding season. In both subspecies, the number of calls varied with time of day; Antarctic blue whale calls were more prevalent in the night to early morning, while Australian blue whale calls were detected more often from midday to early evening. Using passive acoustic monitoring, we show that each subspecies adopts different seasonal and daily call patterns which may be related to the ecological strategies of these subspecies. This study demonstrates the importance of passive acoustics in enabling us to understand and monitor subtle differences in the behavior and ecology of cryptic sympatric marine mammals.
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In Chapter 13, Kana Mutombo presents a holistic framework for adaptation to climate change in relation to port infrastructure. The changes in the global economy due to increasing trade and the globalisation of production have led to developments in international logistics, shipping technology, industry consolidation and environmental regulations, which will change the way in which ports operate in the 21st century. The role of ports is changing gradually from being perceived as a set of complex infrastructures to becoming a major player in national supply chain management. The sharp increase in the imports and exports that flow through ports has also led to a greater focus on the vulnerability of port infrastructure to climate change. Climate change-induced effects can have very adverse effects on port infrastructure, resulting in the failure of foundations, the degradation of superstructure material, increased storm and flood damage and the failure of roofs and cladding. The author introduces a three-tier model for port infrastructure adaptation to the climate change framework, with a focus on policy, management and technology.
Technical Report
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The purpose of the review was to analyse in detail the available information on the broad situation of the marine ecosystems of Mozambique, and highlight the critical gaps in available data or research. The report will enable Fondation Ensemble and its partner the Oak Foundation, or any other interested stakeholder, to deepen their understanding of the broad marine ecosystem situation in Mozambique and help establish intervention priorities for practical field initiatives and/or on research within the areas of marine biodiversity conservation, and/or sustainable fishing. Mozambique is located along the southern coast of East Africa. The 2,470 km coastline and a diverse and productive continental shelf area of about 104,300 km2 are of paramount importance for the country. The Mozambican coastline is characterized by a wide diversity of habitats including sandy and rocky beaches; sand dunes, coral reefs, estuaries, bays, seagrass beds and mangrove forests, which support pristine ecosystems, high biological diversity, high endemism, and endangered species. The coastline can broadly be classified into three regions from north to south, each supporting a variety of marine ecosystems; 1) the coral coast, 2) swamps and 3) parabolic coastal dunes. In addition to these three main regions, the deep-water pelagic and seabed ecosystems contribute to the majority of the country’s exclusive economic zone (EEZ). The various natural resources therein, sustain about half the population of Mozambique living in the coastal zone, help support the country’s economy through fisheries, tourism, industries and communications. There are more than 20 million people living in Mozambique with a growth rate of 2.5% per annum, the majority of which lives below the poverty line and has no access to improved water and sanitation. About two-thirds of the total population resides within the coastal region.
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The International Whaling Commission’s (IWC) Database‐Estimation and Software System (DESS) was designed to standardise IWC line‐transect survey data storage and streamline abundance estimation, including abundance estimation by small management area to inform decision making. Not only was DESS designed to accommodate all International Decade of Cetacean Research (IDCR) and Southern Ocean Whale and Ecosystem Research (SOWER) surveys, but also national surveys, such as the Japanese surveys in the Antarctic and North Pacific, and multi‐national surveys conducted in the North Atlantic. The standard software for estimating abundance was program Distance, which could estimate abundance in designed survey blocks, however, management procedures required estimation not just in survey blocks but also in smaller regions that could be defined by the user. This added a spatial component to data selection which led to the inclusion of a geographical information system (GIS). This paper describes the data stored in DESS and the features available for data retrieval and analysis.
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As part of the International Whaling Commission’s SOWER blue whale research programme, two sighting vessels, the Shonan Maru and the Shonan Maru No.2, surveyed the Madagascar Plateau between 25° and 35°S, 40° and 45°E, in December 1996. A total of 95 sightings of 110 blue whales (assigned in the field as pygmy blue whales – see discussion), 14 sightings of 21 blue whales (subspecies undetermined) and 12 sightings of 13 ‘like blue’ whales was made in 23 days. In the first half of the survey, the whole research area was covered in a mainly pre-determined zigzag search pattern, and the associated sightings and effort have been used to derive density estimates for blue whales for the area. Sightings in the second half of the survey, where effort was directed at blue whale concentrations, have only been used to provide supplementary data for calculation of the effective search half-width and mean school size. The resulting population estimate is 424 (CV = 0.42), or 472 (CV = 0.48) whales when ‘like blue’ sightings are included. Dive times and surfacing behaviour recorded in just over 21h of monitoring suggest that the assumption that all groups on the trackline were seen (g(0) = 1) is reasonable. As the geographical extent of the survey area was substantially less than that of past catches of blue whales in the region in December, this estimate must refer to only a portion (possibly about one third) of the total population. Some evidence of feeding on euphausiids in the region was detected, possibly as a consequence of a localised upwelling cell at the southern tip of Madagascar.
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A total of 111 samples from Southern Hemisphere blue whales were sequenced for 420 base pairs of the mitochondrial control region and all but one of those were genotyped over seven microsatellite loci. Comparisons were made between samples from three broad geographic regions: the southeast Pacific Ocean; Indian Ocean; and around the Antarctic continent. Each of these strata was found to be highly differentiated from the others, in both mitochondrial and nuclear data. The genetic differentiation between the geographic ranges of the nominal subspecies (i.e. true blue whales in Antarctica vs. pygmy blues in Pacific and Indian Oceans) was not markedly greater than between the populations of pygmy blue whales. Assignment tests using the microsatellite data provide some insight into detection of feeding-season mixing, although existing methods have some limitations.
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Cetaceans observed in Maldivian waters were recorded during the period August 1990 to June 2002, from both vessels-of-opportunity and dedicated cetacean-watching cruises. A total of 1,829 cetacean sightings were recorded during 535 days at sea (equivalent to 261 standardised days). There were 83 multispecies sightings, plus a further 58 sightings without associated effort data and 129 strandings were recorded by the author and others, making a total of 2,108 cetacean records. In all, 20 different species were positively identified from sightings. Spinner dolphins were the most abundant species seen, accounting for 35% of sightings and 53% of numbers. This species showed a clear diurnal pattern of behaviour, with many schools entering the atolls in the early morning, and leaving in the late afternoon. Spinner dolphins regularly occurred with pantropical spotted dolphins and both species associated with yellowfin tuna. Bryde’s whales also associated with yellowfin tuna and appeared to be most common in Maldivian waters during El Niño Southern Oscillation events. Blue whales were only recorded during November to April. Dwarf sperm whales were especially difficult to locate in rough weather but relatively common, making up one sixth of all sightings in flat-calm conditions. Melon-headed whales were particularly common in the south of the Maldives, but rare in the centre and north. Other species recorded were humpback whale, sperm whale, rough-toothed dolphin, Risso’s dolphin, bottlenose dolphin, striped dolphin, Fraser’s dolphin, pygmy killer whale, false killer whale, killer whale, short-finned pilot whale, Blainville’s beaked whale, Longman’s beaked whale and Cuvier’s beaked whale.
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We describe a method for measuring blue whales in which we use an estimate of the range given by the apparent distance of the whale below the horizon, in conjunction with a mozaic of photographs taken through a blow cycle. The likely errors in this technique, not all of which can be fully quantified, are discussed. Average errors are probably less than 10 percent. This method can be used for whales which show little of themselves above water and come to the surface with bodies bent along their long axis
Conference Paper
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The 1997/1998 IWC -SOWER Blue Whale Cruise was carried out in the southeastern Pacific Ocean off the coast of Chile during December 1997 and January 1998. This was the third cruise of the IWC’s programme of research on Southern Hemisphere blue whales and the second to be undertaken under the Southern Ocean Whale and Ecosystem Research (SOWER) initiative. The first was a joint IWC Japanese cruise. The main objective of this programme is to assess the status of “true” blue whales (Balaenoptera musculus intermedia) in the Southern Hemisphere. The initial and present objective of the programme’s research is to obtain scientific information relevant to developing shipboard identification methods of distinguishing “true” blue whales and pygmy blue whales (B. musculus brevicauda). The initial two cruises (in Australian waters in 1995/96 and south of Madagascar in 1996/97) had centered on this aspect. This cruise arose as an opportunity for continuation of this research off the west coast of South America prior to the 1997/98 SOWER Antarctic cruise to Area II. Approaches to be used to meet the research objective included acoustic sampling, genetic analyses of skin samples, and observations of whale behaviour and external morphology. The IWC provided partial funding for the cruise. The research vessels Shonan Maru and Shonan Maru No 2, their crews and equipment and two researchers were provided by the Government of Japan. The Government of Australia provided funding for one researcher, while the Government of the USA provided funding for one researcher, and sonobuoys used for acoustic research.The research vessels were the same as those used during the previous two cruises.
Article
Blue whales were seen often in the Indian Ocean. They occur over a wide latitudinal range even in mid-summer when they are normally thought to be feeding in the Antarctic. The blue whales seen in lower latitudes are pygmy blue whales, Balaenoptera musculus brevicauda. In mid-summer they are segregated from the true blue whales B. m. musculus (being found in more northerly waters) although the sub-species cannot be distinguished at sea due to difficulties in identification. The present analysis also suggests pygmy blue whales are found in the W region of the South Pacific and the E region of the South Atlantic. -from Authors