SC/63/IA11

Changes in baleen whale distribution patterns between
CPII and CPIII
HIROTO MURASE1, SHIGETOSHI NISHIWAKI1, KOJI MATSUOKA1, TAKASHI HAKAMADA1, AND TOSHIHIDEKITAKADO2
1 The Institute of Cetacean Research, 4-5 Toyomi-cho, Chuo-ku, Tokyo, 104-0055, Japan
2 Tokyo University of Marine Science and Technology, 4-5-7 Konan, Minato-ku, Tokyo, 108-8477, Japan
ABSTRACT
Changes in spatial distribution patterns of large baleen whales (southern right, fin, sei and humpback whales) in relation to
Antarctic minke whales were examined in Area I, IV and V-W using data obtained in IDCR/SOWER CPII and CPIII. Firstly,
probabilities of occurrences of large baleen whales and Antarctic minke whales were estimated spatially at a scale of 10×10 km
grid cell. Then occupied area index (probabilities of presence of Antarctic minke whales minus probabilities of presence of large
baleen whales) were calculated. Environmental condition in Area I was different between CPII and CPIII. The 5ºC SST isotherm
as proximity of the Polar Front (PF) was intruded in the survey area up to 65ºS in CPII especially in the east of 90ºW while it was
remained in the northern edge of the survey area (around 60ºS) in CPIII. Probability of presence of Antarctic minke whales in
CPII was high where continental shelf break and PF were close together along the Antarctic Peninsula. Such convergence of PF to
the Antarctic Peninsula and high density of Antarctic minke whales were not observed in CPIII. In addition, number of sightingsof fin, sei and humpback whales were increased in Area I from CPII to CPIII. Area occupied by these three whales was increasedin Area I. Number of sightings of southern right, fin and humpback whales was increased in Area IV from CPII to CPIII. Area
occupied by these three whales was increased in Area IV. Number of sightings of fin and humpback whales was increased in Area
V-W from CPII to CPIII. Area occupied by these two whales was increased in Area V-W. The apparent decrease of abundance ofAntarctic minke whales was reported in Area I, IV and V-W. It can be hypothesized that increase in number and extent of spatial
distributions of large baleen whales in survey areas could results in (1) increase in number of Antarctic minke whales in the southof ice edge (2) increase in longitudinal (east-west) movement of Antarctic minke whales within stock boundaries and (3) effect on
demographic parameters of Anarchistic minke whales through direct/indirect competition. In addition, changes in environmental
conditions such as locations of front and sea ice edge between CPII and CPIII should also be considered. Further, the substantialchange in the survey design as in the case of Area I impedes the direct comparison of abundance between CPII and CPIII.
Reasons for difference of abundance estimates of Ataractic minke whales between CPII and CPIII should be combinations ofabove mentioned factors. Region-specific integrated approach should be taken to evaluate the reasons because it is obvious thatfactors affecting abundance estimates are different from region to region.

INTRODUCTION
The International Whaling Commission (IWC) conducted the Antarctic minke whale (Balaenoptera
bonaerensis) abundance assessment cruises from 1978/79 to 2009/10 in the Antarctic in austral summer as
reviewed by Matsuoka, et al. (2003). The names of the cruises were firstly the International Decade of Cetacean
Research programme (IDCR, from 1978/79 to 1995/96) and then the Southern Ocean Whale and Ecosystem
Research programme (SOWER, from 1996/97 to 2009/10). These cruises covered three circumpolar surveys forthe purpose of comprehensive assessments: 1978/79-1983/84 (first circumpolar, CPI), 1984/85-1990/91 (second
circumpolar, CPII) and 1991/92-2003/04 (third circumpolar, CPIII). A noticeable abundance decline from CPII
to CPIII using the IWC standard abundance estimation method (Branch, 2006a) has raised questions whether the
decline is true or apparent. Discussion on reasons for the difference of the estimates between CPII and CPIII is
ongoing in the Scientific Committee of IWC (IWC/SC).
It was reported that number of large baleen whales such as blue, fin and humpback whales wasincreased in some region of the Antarctic in the period of the three circumpolar surveys (Branch, et al., 2004;
Matsuoka, et al., 2006; Branch, in press). Though effect of increase in number of large baleen whales onabundance of Antarctic minke whales was pointed out (Branch, 2006b), the effect has not been examined fully.
In this paper, changes in baleen whale distribution patterns between CPII and CPIII in relation to Antarctic
minke whales were examined in Area I (120ºW-60ºW), IV (70ºE-130ºE) and V-W (130ºE-170ºW) where sea ice
conditions in the south of the ice edges were similar between CPII and CPIII.
MATERIALS AND METHODSStandard data set prepared by Burt (2004) was used as data of sighting effort and sighting of Antarctic minke
whales. Primary sighting data of southern right (Eubalaena australis), fin (B. physalus), sei (B. borealis) andhumpback (Megaptera novaeangliae) whales corresponding to the standard effort data were extracted from the
IWC Database-Estimation System Software (DESS) (Strindberg and Burt, 2000). Like minke whales were notincluded in the analysis. Duplicate sightings were excluded in this analysis. Because the objective of thisanalysis was not estimation of abundance but estimation of probability of occurrence in a certain grid cell, no1

truncation and smearing was applied to the sighting data. Number of sightings used in the analysis is shown in
Table 1.
The survey areas were divided into 10×10 km grid cells. The effort data were separated in 1 km
segments and then aggregated in the grid cells. The sighting data were allocated to 10×10 grid cells based on thegeographic coordinates of the sighting positions. Let Yi be the number of school of whales in the i-th grid cell,and Xi denote the presence or absence of whales as

1 if Yi  0,
Xi  
0 o.w.
Then a spatial smoother using GAM having a binomial error distribution with the logistic link function isconsidered as,logpi  o   f k ( zik ) ,1  pikwherepi = E[Xi]: probability of presence of Antarctic minke/large baleen whales in the i-th grid cell

 o : an intercept
f k : a nonparametric smooth function of the k-th explanatory variablezik : the value of the k-th covariate in the i-th grid cell
The probabilities of presence of Antarctic minke and large baleen whales were estimated separately. Small
number of sightings of large baleen whales in CPII limited species by species estimation of probabilities ofpresence. Therefore, they were treated as large baleen whales in this analysis. Number of grid cells used in themodeling is summarized in Table 1. An interaction term of latitude and longitude (latitude×longitude) and depth
were used as covariates in the models in Area IV and V-W. The 2-minute gridded global relief data
(ETOPO2v2) (U.S. Department of Commerce, National Oceanic and Atmospheric Administration, National
Geophysical Data Center 2006) was used as depth data. It was reported that sea surface temperature (SST) in
Area I in CPII was high especially in the east of 90ºW where the Antarctic Peninsula is located (Kasamatsu, etal., 2000a). Therefore, an interaction term of distance from the continental shelf break (800 m isobaths) anddistance from the 5ºC SST isotherm (shelf break×PF) was also used as covariates in Area I. The 5ºC SST
isotherm is considered as proximity of the Polar Front in austral summer as described in Belkin and Gordon(1996). Satellite derived SST data, the AVHRR Pathfinder Version 5 (PO.DAAC, 1985) was used to identified
the isotherm. January monthly daytime SST data corresponding to the survey area and years were used.
Circumpolar surveys (CPII and CPIII) were used as a categorical covariate in all areas. The surveys in each Area
were completed in one year in CPII while it took 2 to 3 years in CPIII for the completion (Table 1). Number ofgrid cells used in the modeling is summarized in Table 2. All geographically referenced data used in this analysis
were converted to the South Pole Lambert azimuthal equal area projection to obtain size of area accurately as
much as possible. Central meridians and latitude of origins were different in each management area (Table 3).
Smoothness parameters were estimated with the generalized cross-validation (GCV). For these analyses, themgcv package (Wood, 2006) version 1.7-2 of R software version 2.12.1 (R Development Core Team 2010) wasused. Probabilities of presence of Antarctic minke and large baleen whales in unsurveyed gird cells were
estimated using the fitted model.
To investigate extent of spatial distribution overlap between Antarctic minke whales and large baleen
whales, an index, occupied area index was calculated as:zi  p x,i  p y,iwherezi : occupied index in the i-th grid cell

p x,i : probability of presence of Antarctic minke whales in the i-th grid cellp y ,i probability of presence of large baleen whales in the i-th grid cell2

If the index is 1, only Antarctic minke whales were presented in the i-th grid cell while only large baleen whales
were presented if the index is -1. If the index is 0, probabilities of presence of Antarctic minke whales and large
baleen whales in the i-th grid cell were identical.
Sea ice conditions at the time of survey prepared by Murase et al. (2011) were used in the distribution
maps for illustrative purpose.
RESULTSArea I
CPII, latitude×longitude and shelf break×PF were significant at 0.05 level in the model for Antarctic minke
whales while all covariates except CPIII were significant in the model for large baleen whales (Table 4).
Observed distribution patterns and estimated probabilities of presence of Antarctic minke whales in Area I in
CPII and CPIII are shown in Fig. 1. Position of the 5ºC SST isotherm as proximity of PF was also shown in Fig.
1. The 5ºC SST isotherm in CPII was around 60ºS between 120ºW and 100ºW and it was abruptly intruded
toward south up to 65ºS in the east of 100ºW. It should be noted that the survey design between CPII and CPIII
was different. Whole area south of 60ºS was surveyed in CPIII while only south of 65ºS was surveyed in CPII.
Two high density areas of Antarctic minke whales were observed in CPII. One was along the ice edge between
120ºW and 100ºW and the other was along the 5ºC SST isotherm between 95ºW and 70ºW. Position of the 5ºC
SST isotherm in CPIII was remained around 60ºS and no intrusion to south was observed. One high density areaof Antarctic minke whales was observed along the ice edge between 120ºW and 100ºW. Observed distribution
patterns and estimated probabilities of presence of large baleen whales (fin, sei and humpback whales) in Area I
in CPII and CPIII are shown in Fig. 2. Some concentrations of large baleen whales were observed between
110ºW and 90ºW in CPII and they were expanded in CPIII. In addition, Concentrations of large baleen whales
were observed between 80ºW and 60ºW in CPIII where few animals were observed in CPIII. Spatial distribution
patterns of occupied area indices in CPII and CPIII are shown in Fig. 3. Most of the survey area was occupied by
Antarctic minke whales in CPII while large baleen whales expanded their occupied area in CPIII especiallybetween 90ºW and 60ºW. Average occupied indices in CPII and CIII were 0.21 and 0.05, respectively.
Area IV
All covariates (CPII, CPIII, depth and latitude×longitude) were significant at 0.05 level in the models for
Antarctic minke whales and large baleen whales (Table 4). Observed distribution patterns and estimatedprobabilities of presence of Antarctic minke whales in Area IV in CPII and CPIII are shown in Fig. 4. Overall
distribution patterns were similar between CPII and CPIII but probability of presence was decreased in CPIII.
Observed distribution patterns and estimated probabilities of presence of large baleen whale in Area IV in CPII
and CPIII are shown in Fig. 5. Southern right, fin and humpback whales were sighted. Large baleen whales weremainly distributed northern part of the longitudinal range between 90ºE and 100ºE in CPII. Few right whales andno fin whales were sighted in CPII. In contrast, number of sightings of these three species and their extent of
distribution area were increased in CPIII. Spatial distribution patterns of occupied area indices in CPII and CPIII
are shown in Fig. 6. Most of Area IV was occupied by Antarctic minke whales in CPII except northern part ofthe longitudinal range between 90ºE and 100º E. In contrast, large whales expanded their occupied area from80E to 120E in longitudinal direction and to the ice edge in the south. Average occupied indices in CPII and CIII
were 0.11 and -0.06, respectively.
Area V-W
All covariates (CPII, CPIII, depth and latitude×longitude) were significant at 0.05 level in the models for
Antarctic minke whales and large baleen whales except CPIII in the model for Antarctic minke whales (Table 4).
Observed distribution patterns and estimated probabilities of presence of Antarctic minke whales in Area V-W in
CPII and CPIII are shown in Fig. 7. Overall distribution patterns of Antarctic minke whales were similar
between CPII and CPIII but probability of presence was decreased in CPIII. Observed distribution patterns andestimated probabilities of presence of large baleen whales in Area V-W in CPII and CPIII are shown in Fig. 8.
Fin and humpback whales were sighted. Distribution of large baleen whales was scarce throughout the survey
area in CPII. In contrast, number of sightings of these species and their extent of distribution area were increased
especially longitudinal range between 150ºE and 170ºE in CPIII. Spatial distribution patterns of occupied area
indices in CPII and CPIII are shown in Fig. 9. Occupied area of large whales in CPIII was increased between
150ºE and 170ºE and it extended to the ice edge. Average occupied indices in CPII and CIII were 0.21 and 0.08,
respectively.

3

DISCUSSION
Area IThe results of this paper suggested change in position of the 5ºC SST isotherm could substantially affected the
distribution patterns of Antarctic minke whales. It has been well documented that Antarctic minke whales arepagophilic species meaning that they are distributed along and within sea ice in the austral summer (Kasamatsu,
et al., 2000b; Murase, et al., 2002; Kelly, et al., 2009). However, high density of Antarctic minke whales wasobserved in the offshore of the western Antarctic Peninsula (WAP) along the 5ºC SST isotherm in CPII. In thispaper, the 5ºC SST isotherm was used as proximity of PF. PF is a strong jet within the Antarctic Circumpolar
Current (ACC) flowing eastward continuously around Antarctica and the position showed interannual variability(Moore, et al., 1997). Antarctic minke whales almost exclusively feed on Antarctic krill (Tamura and Konishi,
2010). Habitat of Antarctic krill is limited in the south of PF (Miller and Hampton, 1989). WAP is known as
breeding ground of Antarctic krill which sustain the highest densities in the South Atlantic. Intrusion of the 5ºC
SST toward south up to 65ºS in the east of 100ºW and associated small scale eddies could cause high density of
Antarctic krill in the offshore region of WAP. As the results, high density area of Antarctic minke whales could
be formed along the 5ºC SST isotherm. In contrast, such high density area of Antarctic minke whales was notobserved in CPIII when the 5ºC SST isotherm remained in the north of 60ºS. The difference of environmental
condition between CPII and CPIII should be taken account to investigate reasons for the difference of theabundance estimates of Antarctic minke whales between CPII and CPIII. Abundance of humpback whales in
Area I was increased from CPII to CPIII (Branch, in press). Though area specific abundance of fin and sei
whales in CPII and CPIII has not been estimated, it is obvious that their number was increased from CPII to
CPIII given number of sightings. It should be stressed that the survey design between CPII and CPIII was totallydifferent. In such case, direct comparison of abundance estimates between CPII and CPIII is not impossible but
extremely difficult.
Area IV and Area V-W
It was reported that abundance of humpback whales was increased from CPII and CPIII in Area IV and VI-W
(Branch, in press). Analysis using JARPA data also suggested similar trend (Matsuoka, et al., in press).
Breeding stock D of humback whales is mainly distributed in Area IV while breeding stock E is mainly
distributed in Area V-W. A population dynamics modelling indicated that breeding stock D and E would recover
to pristine level within 2 decades (Johnston and Butterworth, 2005). Abundance estimates of southern right andfin whales in Area IV and V-W in CPII and CPIII has not been reported but it is obvious that these two species
were also increased from CPII to CPIII given number of sightings. It was reported that the Indian Ocean stock(including Area IV) of fin whales were increased recently based on JARPA data (Matsuoka, et al., 2005). As
suggested by the analysis in this paper, these large baleen whales expanded their distribution area along with
their abundance increase.
Recommendation for the future study
It can be hypothesized that increases in number and extent of spatial distributions of large baleen whales insurvey areas could results in (1) increase in number of Antarctic minke whales in the south of ice edge (2)increase in longitudinal (east-west) movement of Antarctic minke whales within stock boundaries and (3) effecton demographic parameters of Anarchistic minke whales through direct/indirect competition. In addition,changes in environmental conditions such as locations of front and sea ice edge between CPII and CPIII should
also be considered. Further, the substantial change in the survey design as in the case of Area I impedes the
direct comparison of abundance between CPII and CPIII. Reasons for difference of abundance estimates ofAtaractic minke whales between CPII and CPIII should be combinations of above mentioned factors.
Region-specific integrated approach should be taken to evaluate reasons because it is obvious that factors
affecting abundance estimates are different from region to region.
ACKNOWLEDGEMENT
The authors express their thanks to the crews and the researchers who engaged in the surveys to collect valuable
data.
REFERENCES
Belkin, I. M. and Gordon, A. L. 1996. Southern Ocean fronts from the Greenwich meridian to Tasmania. J. Geophys. Res. 101: 3675-3696.
Branch, T. A., Matsuoka, K. and Miyashita, T. 2004. Evidence for increases in Antarctic blue whales based on Bayesuan modelling. Mar.
Mamm. Sci. 20: 726-754.
Branch, T. A. 2006a. Abundance estimates for Antarctic minke whales from three completed circumpolar sets of survey, 1978/79 to 2003/04.
Paper SC/58/IA18, presented to the 58th IWC Scientific Committee, May 2006 (unpublished). 28pp.

4

Branch, T. A. 2006b. Possible reasons for the appreciable decrease in abundance estimates for Antarctic minke whales from the
IDCR/SOWER surveys between the second and third circumpolar sets of cruises. Paper SC/58/IA4 presented to the 58th IWC ScientificCommittee, May 2006 (unpublished). 8pp.
Branch, T. A. in press. Humpback whale abudance south of 60ºS from three completed sets of IDCR/SOWER circumpolar surveys. J.
Cetacean Res. Manage.
Burt, M. L. 2004. Overview of the standard dataset of IDCR/SOWER data. Paper SC/56/IA2 presented to the 56th IWC ScientificCommittee, June 2004 (unpublished). 3pp.
Johnston, S. J. and Butterworth, D. S. 2005. A Bayesian assessment of the west and east Australian breeding populations (stocks D and E) of
Southern Hemisphere humpback whales. Paper SC/57/SH15 presented to the 57th IWC Scientific Committee, May 2005 (unpublished).
25pp.
Kasamatsu, F., Ensor, P., Joyce, G. G. and Kimura, N. 2000a. Distribution of minke whales in the Bellingshausen and Amundsen Seas
(60ºW-120ºW), with special reference to environmental/physiographic variables. Fish. Oceanogr. 9: 214-223.
Kasamatsu, F., Matsuoka, K. and Hakamada, T. 2000b. Interspecific relationships in density among the whale community in the Antarctic.
Polar Biol. 23: 466-473.
Kelly, N., Peel, D., Pike, D., Bravington, M. V. and Gales, N. 2009. An aerial survey for Antarctic minke whales in sea ice off east
Antarctica: a pilot study. Paper SC/61/IA37 presented to the 61st IWC Scientific Committee, May 2009 (unpublished). 14pp.
Matsuoka, K., Ensor, P., Hakamada, T., Shimada, H., Nishiwaki, S., Kasamatsu, F. and Kato, H. 2003. Overview of minke whale sightingssurveys conducted on IWC/IDCR SOWER Antarctic cruises from 1978/79 to 2000/01. J. Cetacean Res. Manage. 5: 173-201.
Matsuoka, K., Hakamada, T., Kiwada, H., Murase, H. and Nishiwaki, S. 2005. Abundance increases of large baleen whales in the Antarctic
based on the sighting survey during Japanese whale research program (JARPA). Global Env. Res. 9: 105-115.
Matsuoka, K., Hakamada, T. and Nishiwaki, S. 2006. Distribution and abundance of humpback, fin and blue whales in the Antarctic Areas
IIIE, IV, V and VIW (35°E-145°W). Paper SC/D06/J7, presented to the Intersessional Workshop to Review Data and Results from Special
Permit Research on Minke Whales in the Antarctic, December, 2006 (unpublished). 37pp.
Matsuoka, K., Hakamada, T., Kiwada, H., Murase, H. and Nishiwaki, S. in press. Abundance estimates and trends for humpback whales(Megaptera novaeangliae) in Antarctic Areas IV and V based on JARPA sighting data. J. Cetacean Res. Manage.
Miller, D. G. M. and Hampton, I. 1989. Biology and ecology of the Antarctic krill (Euphausia superba Dana): A review. BIOMASS Scientific
Series. 9.
Moore, J. K., Abbott, M. R. and Richman, J. G. 1997. Variability in the location of the Antarctic Polar Front (90º-20ºW) from satellite sea
surface temperature data. J. Geophys. Res. 102: 27825-27833.
Murase, H., Matsuoka, K., Ichii, T. and Nishiwaki, S. 2002. Relationship between the distribution of euphausiids and baleen whales in the
Antarctic (35ºE-145ºW). Polar Biol. 25: 135-145.
Murase, H., Matsuoka, K., Hakamada, T., Nishiwaki, S., Wada, A. and Kitakado, T. 2011. Open sea area in the south of the ice edge in
IDCR/SOWER CPII and CPIII. Paper SC/63/IA9 presented to the 63rd IWC Scientific Committee, May 2011 (unpublished).
Physical Oceanography DAAC. 1985. AVHRR Pathfinder L3 Monthly Daytime SST Version 5. NASA JPL Physical Oceanography DAAC,
Pasadena, USAR Development Core Team. 2010. R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna,
Austria.
Strindberg, S. and Burt, M. L. 2000 IWC Database-Estimation System Software (DESS) User Manual. RUWPA, University of St Andrews.
Tamura, T. and Konishi, K. 2010. Feeding habits and prey consumption of Antarctic minke whale (Balaenoptera bonaerensis) in theSouthern Ocean. Journal of Northwest Atlantic Fishery Science. 42: 13-25.
U.S. Department of Commerce, National Oceanic and Atmospheric Administration, National Geophysical Data Center, 2006. 2-minute
Gridded Global Relief Data (ETOPO2v2)
Wood, S., N. 2006 Generalized additive models: an introduction with R. Boca Raton: Chapman & Hall.

5

Table 1. Number of schools used in the analysis.
Area

CP
CPII

Area ICPIII
CPIIArea IV

CPIII
CPII

Area V
West

CPIII

Year

Minke
whale
698
223
62
46
331
434
85
121
206
344
89
142
231

Longitude

1989/1990 120ºW-60ºW
1993/1994 110ºW-80ºW
1999/2000
80ºW-60ºW
2000/2001 120ºW-110ºW
Sub total
1988/1989
70ºE-130ºE
1994/1995
70ºE-80ºE
1998/1999
80ºE-130ºE
Sub total
1985/1986
130ºE-170ºE
2001/2002
130ºE-150ºE
2002/2003
150ºE-170ºE
Sub total

Right
whale
1
0
22
22
0
-

Fin
whale
2
0
21
5
26
0
0
13
13
4
0
36
36

Sei
whale
3
0
0
8
8
-

Humpback
whale
23
12
49
15
76
53
3
223
226
4
14
74
88

Table 2.Number of grid cells used in model fitting.
Area
Area I
Area IV
Area VWest

CP

Grid cell
With effort

Grid cell withminke whale

Grid cell withlarge baleen whale

CPII
CPIII
CPII
CPIII
CPII
CPIII

1,359
1,597
1,482
1,394
911
954

350
215
270
141
205
152

26
83
39
175
7
95

Table 3. Central meridians and latitude of origins used in the the South Pole Lambert azimuthal equal area
projection.
Centralmeridians
90W
100E
165E

Area
I
IV
V

latitudeof origins
66S
65S
69S

Table 4. Results of GAM modelling. Approximate significance levels (p-value) and degrees-of-freedom (df) are
shown for each of the covariate.
Area I

Area
Speices
Adjusted R2
Deviance explained (%)
GCV score
Covariates
CPII
CPIII
Depth
Latitude×longitude
Shelf break × PF

Minke
whale

Area IV

Large
baleen whale

Minke
whale

Area V West

Large
baleen whale

Minke
whale

Large
baleen whale

0.15

0.16

0.13

0.17

0.11

0.21

17.0 %
0.84

30.6 %
0.23

15.4 %
0.71

27.7 %
0.39

13.1 %
0.88

33.7 %
0.29

df

p -valuedf

p -valuedf

p -valuedf

p -valuedf

p -valuedf

p -value

0.35
2.29
28.10

<0.01
0.03
0.56
<0.01
<0.01

10.86
8.73
28.86

<0.01
0.14
<0.01
<0.01
<0.01

3.78
5.19
-

<0.01
<0.01
<0.01
<0.01
-

3.22
14.23
-

<0.01
<0.01
<0.01
<0.01
-

3.54
3.83
-

<0.01
0.03
<0.01
<0.01
-

7.10
7.75
-

<0.01
<0.01
<0.01
<0.01
-

6

Area I CPII Antarctic minke whales ●Area I CPIII Antarctic minke whales ●Fig 1 Estimated probabilities of presence of Antarctic minke whales in Area I in IDCR/SOWER CPII (top) and
CPIII (bottom). Surveyed tracklines (black line), sighting positions of Antarctic minke whales (●) and sea ice
conditions in the south of the ice edge are also shown. Continental shelf break (800 m isobath, brown line) and
5ºC SST isotherm as proximity of the Polar Front (red line) are also shown.

7

Area I CPII large baleen whales (fin ●, sei ● and humpback ● whales)

Area I CPIII large baleen whales (fin ●, sei ● and humpback ● whales)Fig 2. Estimated probabilities of presence of large baleen whales in Area I in IDCR/SOWER CPII (top) and
CPIII (bottom). Surveyed tracklines (black line), sighting positions of fin (●), sei (●) and humpback (●) whales
and sea ice conditions in the south of the ice edge are also shown. Continental shelf break (800 m isobath, brownline) and SST 5ºC isotherm as proximity of the Polar Front (red line) are also shown.

8

Area I CPII Occupied area index

Area I CPIII Occupied area index

Fig 3. Occupied area indices of Antarctic minke whales and large baleen whales in Area I in IDCR/SOWER
CPII (top) and CPIII (bottom). If the index is 1, only Antarctic minke whales were presented in a grid cell while
only large baleen whales were presented if the index is -1. If the index is 0, probabilities of presence of Antarctic
minke whales and large baleen whales in a grid cell were identical. Sea ice conditions in the south of the ice edge
are also shown.

9

Area IV CPII Antarctic minke whales●

Area IV CPIII Antarctic minke whales●

Fig 4. Estimated probabilities of presence of Antarctic minke whales in Area IV in IDCR/SOWER CPII (top)and CPIII (bottom). Surveyed tracklines (black line), sighting positions of Antarctic minke whales (●) and sea
ice conditions in the south of the ice edge are also shown.

10

Area IV CPII large baleen whales (southern right ●, fin ● and humpback ● whales)

Area IV CPIII large baleen whales (southern right ●, fin ● and humpback ● whales)

Fig 5. Estimated probabilities of presence of large baleen whales in Area IV in IDCR/SOWER CPII (top) and
CPIII (bottom). Surveyed tracklines (black line), sighting positions of southern right (●), fin (●) and humpback(●) whales and sea ice conditions in the south of the ice edge are also shown.

11

Area IV CPII Occupied area index

Area IV CPIII Occupied area index

Fig 6. Occupied area indices of Antarctic minke whales and large baleen whales in Area I in IDCR/SOWER
CPII (top) and CPIII (bottom). If the index is 1, only Antarctic minke whales were presented in a grid cell while
only large baleen whales were presented if the index is -1. If the index is 0, probabilities of presence of Antarctic
minke whales and large baleen whales in a grid cell were identical. Sea ice conditions in the south of the ice edge
are also shown.

12

Area V-W CPII Antarctic minke whales ●Area V-W CPIII Antarctic minke whales ●Fig 7. Estimated probabilities of presence of Antarctic minke whales in Area V-W in IDCR/SOWER CPII (top)and CPIII (bottom). Surveyed tracklines (black line), sighting positions of Antarctic minke whales (●) and sea
ice conditions in the south of the ice edge are also shown.

13

Area V-W CPII large baleen whales (fin ●and humpback ● whales)

Area V-W CPIII large baleen whales (fin● and humpback● whales)

Fig 8. Estimated probabilities of presence of large baleen whales in Area V-W in IDCR/SOWER CPII (top) and
CPIII (bottom). Surveyed tracklines (black line), sighting positions of fin (●) and humpback (●) whales and sea
ice conditions in the south of the ice edge are also shown.

14

Area V-W CPII Occupied area index

Area V-W CPIII Occupied area index

Fig 9. Occupied area indices of Antarctic minke whales and large baleen whales in Area V in IDCR/SOWER
CPII (top) and CPIII (bottom). If the index is 1, only Antarctic minke whales were presented in a grid cell while
only large baleen whales were presented if the index is -1. If the index is 0, probabilities of presence of Antarctic
minke whales and large baleen whales in a grid cell were identical. Sea ice conditions in the south of the ice edge
are also shown.

15