Technical Reports of the Institute of Cetacean Research (2019)

pp. 21–31

Technical Report (not peer reviewed)

Dedicated whale sighting vessels as a platform for krill andoceanographic research in the Indo-Paciﬁc region of the Antarctic
Atsushi Wada*
Institute of Cetacean Research, 4–5 Toyomi-cho, Chuo-ku, Tokyo 104–0055, Japan*Contact e-mail: wada@cetacean.jp

ABSTRACTThe Institute of Cetacean Research has conducted research on the ecosystem in the Indo-Paciﬁc sector of the
Antarctic, as part of the JARPA, JARPAII and NEWREP-A whale research programs. As part of the ecosystem
research, oceanographic and krill surveys have been carried out in a systematic manner using dedicated sighting surveys as platform. Krill are key species in the Antarctic ecosystem and changes in its abundance have effects on predators and the whole ecosystem. Changes in the oceanographic conditions will aﬀect distribution
and krill biomass and in turn the abundance and distribution of whales. Changes in oceanographic conditions
might indicate eﬀects of climate changes. This paper describes the technical aspects of the krill and oceanographic surveys conducted by the Institute of Cetacean Research from dedicated sighting vessels.

INTRODUCTION
The Institute of Cetacean Research (ICR) has conducted
research on the ecosystem in the Indo-Paciﬁc sector of
the Antarctic in a systematic manner for a considerable
number of austral summer seasons. The ecosystem research involved oceanographic and krill surveys, whichwere conducted as part of the JARPA (1987/88–2004/05),
JARPAII (2005/06–2013/14) and NEWREP-A (2015/16–
2018/19) whale research programs.
Oceanographic and krill research is important tounderstand changes in the Antarctic ecosystem. Krill
are key species in the Antarctic ecosystem and changes
in their abundance have eﬀects on predators and thewhole ecosystem. Changes in the oceanographic conditions will aﬀect distribution and krill biomass and inturn the abundance and distribution of whales. Changes
in oceanographic conditions might indicate eﬀects ofclimate changes. Fujise and Pastene (2018) presented
scientiﬁc evidence for historical and current changes in
the Antarctic ecosystem. Historical changes were consistent with the ʻkrill surplus hypothesisʼ (Laws, 1977; 1985)
while current changes were interpreted as the reverse ofthis hypothesis.
This paper describes the technical aspects of the krill
and oceanographic surveys conducted by the ICR fromdedicated sighting vessels. Oceanographic and krill survey plans and results have been presented and discussed
at annual meetings of the International Whaling Commis-

sion Scientiﬁc Committee (IWC SC) as well the Convention
for the Conservation of Antarctic Marine Living Resources
Working Group on Ecosystem Monitoring and Management (CCAMLR-EMM). Surveys have been designed andconducted by following technical advice of experts fromthese meetings. Also this paper shows as an example, theresults of the oceanographic and krill surveys conductedby NEWREP-A in the 2018/19 austral summer season.

DEDICATED SIGHTING VESSELS
Oceanographic and krill surveys were conducted fromdedicated whale sighting surveys. A total of three research vessels were used during the NEWREP-A, which
covered the IWC management Areas using zigzag
tracklines (Figure 1, Table 1): Yushin-Maru No.2 (YS2;
747GT, Figure 2), Yushin-Maru No.3 (YS3; 742GT, Figure 3)
and Kaiyo-Maru No.7 (KY7; 649GT, Figure 4). The transducers of Quantitative Echosounder (EK80; Simrad, Norway) were hull-mounted at a depth of 4.3 m below thesea surface in the case of YS2 and YS3. The transducers of
Quantitative Echosounder (EK60; Simrad, Norway) were
hull-mounted at a depth of 4.7 m below the sea surface inthe case of KY7. The electrical winch (TS-F2, Tsurumi-Seiki
Co., Ltd., Japan, Figure 5) was set at the right side deck inthe case of YS2 and YS3.

INSTRUMENTS USED FOR KRILL SURVEY
All three survey vessels were mounted with Quantitative
Echosounders for acoustic data recording. These data are21

Technical Reports of the Institute of Cetacean Research (2019)

Figure 1.

Research area and tracklines. Blue line: surveyed trackline of Yushin-Maru No. 2, Green line: surveyed
trackline of Yushin-Maru No.3, Red line: surveyed trackline of Kaiyo-Maru No.7, Gray line: boundary between northern and southern research area, Turquoise line: ice edge, Brown: Antarctic continent.

Table 1
Research area and vessels covered by NEWREP-A. YS2: Yushin-Maru
No. 2, YS3: Yushin-Maru No. 3, KY7: Kaiyo-Maru No. 7.
Area

Season2015/162016/172017/18

2018/19

III-NE
III-SE

YS2
YS2

IV-NW
IV-SW
Prydz Bay
IV-NE
IV-SE

KY7
KY7
KY7
KY7
KY7

YS3
YS3

V-NW
V-SW
V-NE
V-SE
VI-NW
VI-SW
VI-SW*

Figure 2.

Yushin-Maru No.2 (YS2).

Figure 3.

Yushin-Maru No.3 (YS3).

YS3, KY7
YS3, KY7
YS2, KY7
YS2
YS2, KY7
YS2, KY7YS2*Southern of 69°S

used to estimate distribution and biomass of krill in the
research area. Such estimate requires information on krill
species and krill body length, which is obtained from net
sampling. Two types of net sampling were used, IsaacsKidd Midwater Trawl (IKMT) and small ring net sampling.
The IKMT sampling was carried out by KY7 while thesmall ring net was used by YS2 and YS3. Due to its small
size, the small ring net cannot be used for obtaining representative information of some quantitative traits (e.g.
number of individuals and length frequency distribution
22of krill in the area) but the qualitative information (e.g.
the species occurring in the echo-signs) can be obtained.
Quantitative Echosounder
All three vessels steamed on the predeterminedtracklines and acoustic data were recorded continuously.
The usual navigation speed of YS2 and YS3 was approxi-

Dedicated whale sighting vessels as a platform for krill and oceanographic research in the Indo-Pacific region of the Antarctic

Figure 6.

Figure 4.

Procedure for the calibration of EK80 and EK60
Quantitative Echosounders (Based on Simmonds
and MacLennan, 2005).

Kaiyo-Maru No.7 (KY7).

Figure 7.

Figure 5.

The electrical winch at Yushin-Maru No. 3.

mately 11.5 knots. The speed of KY7 was 11.0 knots. All
Quantitative Echosounders operated with frequencies at
38 kHz, 120 kHz and 200 kHz. Maximum data recording
depth was set at 500 m.
Standard calibration of Quantitative Echosounders wasmade using a standard method (Demer et al., 2015) inthe vicinity of Japan and also at the research area before
starting the research. This was done for every survey todetermine the likely eﬀective acoustic sampling range
and the potential for detecting krill for multiple frequencies over the required survey depth.
Also calibration between EK80 (YS2, YS3) and EK60
(KY7) Quantitative Echosounders was conducted when
YS3, YS2 and KY7 passed nearby following the procedureof Simmonds and MacLennan (2005) (Figure 6).

IKMT sampling net at the Kaiyo-Maru No. 7.

IKMT sampling
As noted above, the KY7 was equipped with an IKMT
designed by Nippon-Kaiyo Co., Ltd. Japan (Figure 7). The
purpose of IKMT sampling was the collection of qualitative and quantitative information for krill (e.g. determination of the species occurring in echo signs andrepresentative numbers and krill length frequencies). The
sampling was conducted during day time. The IKMT was
3.66 m in mouth diameter and 18.43 m length. For comparative purposes with the small ring net, 0.5 mm meshsize was used for IKMT.
Data Storage Tag (DST) was installed at the mouth of
the IKMT to record actual depth of the net. On average,
it took approximately 11 minutes per haul excludingtime for setting. The target depth of net sampling was
set based on depth of echo sign but the maximum depth
was 200 m. The depth of the mouth was monitored at thebridge by PI sensor (PI32; Simrad, Norway). Towing speedof IKMT was 1.0 m/s.
Small ring net sampling
All three vessels were equipped with a small ring net that
had a mouth opening of 1.0 m across, and 2.4 m or 3.0 m
length. Mesh size was 0.5, 1.5 or 4.5 mm (Nippon-Kaiyo
Co., Ltd. Japan, Rigosha & Co., Ltd. Japan, Figure 8) (Tra23

Technical Reports of the Institute of Cetacean Research (2019)

than et al., 2001). At the time of the sampling the vessels
stopped their engines.
The target depth of net sampling followed echo backscattering to a maximum of 200 m. If a Light Emitting
Diode (LED) and digital compact camera were attachedto the net, the maximum depth was switched to 100 m
because of their pressure capacity. The depth of themouth was estimated visually from the angel of the wirewith a protractor. The accurate depth of the mouth was
conﬁrmed by DST record in the laboratory. If DST were
not used, the accurate depth of the mouth was checkedby PI sensor at the ﬁeld. Hauling speed of the net was approximately 1.0 m/s depending on sea state.
The small ring net sampling was conducted to identify
the species targeted by echo signs. Notably, the purposeof using this net in KY7, was to check eﬃciency of thesmall ring net by comparing the samples with those obtained by IKMT. If the small ring net samples collected sufﬁcient amount of samples to examine length frequency ofkrill and the composition of plankton samples was similar
to those collected by IKMT, the result of the small ring
net are useful. The small ring net hauls were carried out
as in YS2 and YS3, but were only conducted where IKMT
collected swarms of krill.
Sample treatment
All plankton samples were kept in bottles with 10% formalin and/or frozen at −20°C for further analysis in thelaboratory. Preliminary standard measurements (AT) of
krill sampled, were carried out onboard the vessels. The
AT is measured from the front of the eye to the tip of thetelson, the thin, tapered triangular plate at the end of theabdomen (CCAMLR, 2011, Figure 9).
Recording depth of net
A Data Storage Tag (DST Centi-ex, Star Oddi Co., Ltd.,
Iceland, Figure 10) was put at the mouth of the small
ring nets and IKMT for recording temperature and depth
at one second intervals. Temperature Depth Recorders(TDR, AL1, Ishida Engineering, Japan, Figure 11) and PI
sensors were used as an alternative to DST in 2015/16
and 2017/18 NEWREP-A, respectively. The TDR was put inmouth of the net for recording temperature and hydraulic pressure. The PI sensor was put on the small ring net

Figure 9.

Measurement of total body length (AT) of krill(CCAMLR, 2011).

Figure 10.

Figure 8.
24

Small ring net at the Yushin-Maru No. 2.

Figure 11.

The Data Storage Tag (DST).

The Temperature Depth Recorder (TDR).

Dedicated whale sighting vessels as a platform for krill and oceanographic research in the Indo-Pacific region of the Antarctic

Figure 12.

LED with camera used for attracting krill in thesmall sampling net.

and depth read from the display directly at one minuteintervals.
Attracting krill
In some surveys small net sampling was conducted with
LED and a movie recorded the appearance of the mouth.
Almost in all net sampling, a maximum 3,000 lumen LED(FIX NEO 3000 DX, Fisheye Co., Ltd., Japan), digital compact camera (TG-4 Tough, Olympus Co., Ltd., Japan) andhousing system (Nauticam TG3, Fisheye Co., Ltd., Japan)(Figure 12) was put in mouth of net (Wiebe et al., 2004).
The lighting system was not used after the 2015/16
NEWREP-A following recommendations by CCAMLR specialists (CCAMLR, 2016).

INSTRUMENTS USED FOR OCEANOGRAPHICSURVEYS
Oceanographic observations were based on Japan Meteorological Agency (1999) standards and conducted inparallel with krill surveys.
CTD casting
Hydraulic pressure, temperature, salinity, chlorophyll-aand dissolved oxygen were recorded from sea surface
to 500 m depth using Conductivity-Temperature-Depth
proﬁler (CTD). The CTD SBE 19 plus V2 SeaCAT (Sea-Bird
Scientiﬁc Inc., USA, Figure 13) was used by the YS2 andYS3, and the SBE 19 plus SeaCAT (Sea-Bird Scientiﬁc Inc.,
USA) was used by the KY7. The instruments were descended using an electrical winch with diameter of 3 mm
and an overall length of 1,000 m wire. Normally CTD wasdescended to 500 m. The data from the CTD was uploaded for conversion by following the manual. All CTD were
calibrated before every cruise by Sea-Bird Scientiﬁc Inc.

Figure 13.

CTD at Yushin-Maru No. 2.

Seawater sampling
The seawater sampling was carried out for calibrating the
CTD sensors. Niskin water sampling bottles Model-1010
1.2L (General Oceanics, Inc., USA, Figure 14) were used
by YS2 and YS3 and Model-1010 1.7L (General Oceanics,
Inc., USA, Figure 15) was used by KY7. The bottles were
dropped to depths from 0 to 200 m and sampling was
conducted every 20 m. Depth information of samplingbottles was based on the angle of the wire while operating. Accurate depths of sampling bottle were recorded at
the laboratory from the DST or PI sensor.
The seawater was kept in freezers for subsequent
analysis in the laboratory. The sea water was kept in twobottles. One was a 250 mL clarity seawater bottle (WOCE
type 5419-C, Rigosha & Co. Ltd., Japan) for salinity calibration, which was stored at 4°C. The other bottle was forchlorophyll-a calibration. 118 mL of seawater from thebottles was ﬁltrated (Whatman 233303 GF/F 25 mm, GE
Healthcare, USA) (Figure 16). The ﬁlter paper was kept in
8 mL centrifugal tubes (60.452, Sarstedt AG & Co., Germany) ﬁlled with dimethylformamide. The tubes were
stocked in freezer about −20°C (Saito, 2007). After thecruises, salinity was measured by Autosal Salinometer
OSIL 8400B (Ocean Scientiﬁc International Ltd, UK) and
chlorophyll-a was measured by TURNER 10AU Field andLaboratory Fluorometer (Turner Designs, Inc., USA).

25

Technical Reports of the Institute of Cetacean Research (2019)

HOW THE KRILL AND OCEANOGRAPHIC SURVEYS
ARE CONDUCTED FROM A WHALE SIGHTINGVESSEL?

Figure 14.

Niskin water sampling bottle at Yushin-Maru No. 2.

Figure 15.

Niskin water sampling bottle at Kaiyo-Maru No. 7.

Figure 16.

26

Filtrating seawater with ﬁlter paper.

The trackline was designed for the main purpose of abundance estimates of large whales based on the DISTANCE
sampling (Buckland et al., 2015). It followed the accepted
guidelines by the IWC SC for the International Decadefor Cetacean Research/Southern Ocean Whale andEcosystem Research (IDCR/SOWER) cruises (Matsuoka
et al., 2003). The trackline consisted of a zigzag coursechanging direction at each 5°00ʼ longitudinal degree intervals in the northern stratum and at 2°30ʼ longitudinal
degree intervals in the southern stratum. The trackline in
the Ross Sea was set zigzag in north and south to westward or eastward. The zigzag course changed direction at
1°30ʼ latitudinal degree intervals. Also the trackline in the
Prydz Bay changed direction in northward or southward
at 2°30ʼ longitudinal degree intervals. A randomized startpoint was determined based on the IWC SC guidelines(IWC, 2012).
The sighting surveys were conducted during the daytime from an hour after sunrise to an hour before sunset.
The vessel would move through the tracklines at a speedof 11.0–11.5 knots. The survey stopped when the sea
conditions and weather were not appropriate for sighting activities. When the conditions improved, the vessel restarted the survey from the same position on the
trackline. Three researchers participated onboard thevessels, two in charge of the sighting survey and one incharge of the krill and oceanographic surveys.
Details of the sighting survey procedures used by the
ICR can be found in Hakamada and Matsuoka (2017).
Krill survey
The Quantitative Echosounder data were recorded continuously while vessels steamed on the predeterminedtracklines, day and night. Only the acoustic data obtained
when the vessels were on the trackline are used for krill
abundance estimates.
All net sampling was conducted following the echo
sign by the Quantitative Echosounder (Figure 17). Whenthe researcher conﬁrmed a swarm of krill and decided to
tow the net, the sighting survey was stopped and preparation for net sampling was made as soon as possible. In
principle, net sampling was conducted once a day in the2015/16 and 2016/17 NEWREP-A. In order to increase
the number of samples, net sampling was conducted
after each conﬁrmation of echo signs in the 2017/18 and2018/19 NEWREP-A.

Dedicated whale sighting vessels as a platform for krill and oceanographic research in the Indo-Pacific region of the Antarctic

2018/19 NEWREP-A in management Areas III-E and IV.
The surveys were conducted by the research vessels YS2and KY7.

Figure 17.

Echo sign of Antarctic krill by the EK80 of
Yushin-Maru No. 3.

During the IKMT sampling, the vessel steamed approximately at 2.0 knots. In the case of small ring net sampling,
the vessels stopped their engines when reconﬁrming
echo sign. Both sampling was conducted with careful
conﬁrmation of krill swarm location by monitoring of the
Quantitative Echosounder. When the net sampling wascompleted, the vessel re-started sighting surveys fromthe same position on the trackline that had stopped forthe sampling. Preliminary analyses of the sample werecarried out immediately after sampling.
Oceanographic survey
It was planned that oceanographic observations using
CTD casting would cover the whole area, and for this reason the geographical position of the CTD casting stations
would not necessarily coincide with the position of the
net sampling. The CTD casting stations were positioned
at approximately 60 n.miles on the trackline. The vessels stopped their engines when they arrived at the CTD
casting station. Once observations were completed, they
re-started the sighting surveys from the same positionon the tracklines where the vessels had stopped theirengines.
To calibrate the CTD sensors, the stations for seawater
sampling were the same as some CTD casting station.
Each station was positioned approximately within a radius of 120 n.miles in entire research area for covering
the entire area.
Net sampling, CTD casting and seawater sampling wereconducted during day time and smooth sea states.

RESULTS OF THE 2018/19 KRILL AND OCEANOGRAPHIC SURVEY
As an example, this section shows the results of the

Quantitative Echosounder
Calibrations of Quantitative Echosounders were madeon 30 October 2018 by YS2 and on 7 November 2018 by
KY7 in the vicinity of Japan before departure for the Antarctic. During the calibrations, the vesselʼs engines were
stopped for anchoring at sea bottom 37 m for YS2 and48 m for KY7. Calibrations in the survey area were madeon 13 December 2018 by YS2 and on 6 December 2018 by
KY7 before starting the survey on the tracklines. During
the calibrations, the vesselʼs engines were stopped andthe drifting speed was approximate 0.7 knots because
anchoring at that depth could not be achieved in the Antarctic. The data from the Quantitative Echosounders wasrecorded according to setting of calibration in Antarctic.
The Quantitative Echosounders calibration (EK80 in
YS2 and EK60 in KY7) was conducted on 12 November
2018 in Japanese coastal areas. The methodology of
Simmonds and MacLennan (2005) was followed. The
Quantitative Echosounder data were recorded by YS2
and KY7 moving in formation with one in the lead and theanother about 400 m astern, far enough to the side to beclear of the leader vessel's wake. The two vessels took thelead in turns and exchanged positions at the end of eachtransect. Both research vessels recorded Quantitative
Echosounders data while shifting the leaders every 30
minutes four times for two hours. As a result, calibrations
between EK80 and EK60 were recorded shallow over
200 m sea bottom backscattering constantly by all threefrequencies, 38 kHz, 120 kHz and 200 kHz.
Table 2 shows a summary of the total eﬀort spent on
the Quantitative Echosounder survey. This survey was
conducted for a total of 7,195 n.miles along the tracklines(3,365 n.miles in Area III-E, 2,267 n.miles in Area IV-W,
509 n.miles in Prydz Bay and 1,055 n.miles in Area IV-E).
IKMT sampling
IKMT sampling was conducted at a total of 22 stations
by KY7 (10 stations in Area IV-W, seven stations in the
Prydz Bay and ﬁve stations in Area IV-E, Tables 2, 3 andFigure 18). Logistical considerations were also taken into
account to decide whether to proceed with net samplingsuch as the sea state, sea ice as well as other survey priorities.
Small ring net sampling
The small ring net sampling was conducted at a total of 54
27

Technical Reports of the Institute of Cetacean Research (2019)
Table 2
Research item and summary in the 2018/19 NEWREP-A.
Quantitative
Echosounder

Area

IKMT
stations

Small ring net
stations

CTD castingstations

Seawatersampling
stations

DST
stations

Days

n.miles

III-NE
III-SE

39
32

2,175
1,191

—
—

17
28

42
27

5
2

17
28

IV-NW
IV-SW
Prydz Bay
IV-NE
IV-SE

15
17
6
8
9

1,254
1,013
509
587
468

3
7
7
1
4

0
6
1
2
0

19
23
11
8
14

3
2
2
1
1

3
14
7
3
4

Total

72*

7,195

22

54

144

16

76

*The survey was conducted some areas at same day
Table 3
Summary of IKMT sampling in 2018/19NEWREP-A.
Antarctic krill

Area

Ice krill

Bigeye krill

Euphausiids

Copepoda

Other
Zooplankton

FishStations%

Stations%

Stations%

Stations%

Stations%

Stations%

Stations

%

IV-NW
IV-SW
Prydz Bay
IV-NE
IV-SE

2
6
6
0
2

67
86
86
0
50

0
0
1
0
0

0
0
14
0
0

1
0
0
0
0

33
0
0
0
0

0
1
0
0
3

0
14
0
0
75

0
0
1
1
1

0
0
14
100
25

0
2
1
1
2

0
29
14
100
50

1
0
1
0
0

33
0
14
0
0

Total

16

73

1

5

1

5

4

18

3

14

6

27

2

9

YS2 and on 6 December 2018 and 30 January 2019 by KY7
respectively.
Sample contents of the net
A total of 11 species, including three euphausiid species:
Antarctic krill (Figure 20), ice krill E. crystallorophias (Figure 21) and bigeye krill Thysanoessa macrura (Figure 22)
and ﬁsh (Figure 23 and 24), were identiﬁed in the 73 net
sampling contents. Several other species, Hydromedusae,
Siphonophorae, Polychaeta, Pteropoda, Copepoda (Figure 25), Amphipoda and Chaetognatha were conﬁrmed
by small ring net sampling and IKMT sampling. There
were no contents at three net sampling stations.
Figure 18.

Antarctic krill sample of IKMT.

stations by YS2 and KY7 (45 stations in Area III-E, six stations in Area IV-W, one station in the Prydz Bay and two
stations in Area IV-E, Tables 2, 4 and Figure 19). Becauseof weather, sea ice conditions or survey priority reasons,some net sampling stations were skipped. Calibration of
the ﬂow meters was conducted on 10 December 2018 by
28

Distribution of krill
Tables 3 and 4 show the summary of frequencies of occurrence of krill species and Copepoda sampled by the
IKMT and small ring nets, respectively. Antarctic krill was
sampled at 48 stations in entire of survey area. Distribution of surface water temperature was in the range of−1.7°C to 1.9°C. The Antarctic krill were sampled at depths

Dedicated whale sighting vessels as a platform for krill and oceanographic research in the Indo-Pacific region of the Antarctic
Table 4
Summary of small ring net sampling in 2018/19NEWREP-A.
Area

Antarctic krill

Ice krill

Euphausiids

Bigeye krill

Other
Zooplankton

Copepoda

Stations%

Stations%

Stations%

Stations%

Stations%

Stations%

III-NE
III-SE

7
21

41
75

0
0

0
0

6
3

35
11

0
0

0
0

12
18

71
64

16
20

94
71

IV-NW
IV-SW
Prydz Bay
IV-NE
IV-SE

—
4
0
0
—

—
67
0
0
—

—
0
0
0
—

—
0
0
0
—

—
0
0
0
—

—
0
0
0
—

—
0
0
0
—

—
0
0
0
—

—
0
0
1
—

—
0
0
50
—

—
1
1
1
—

—
17
100
50
—

Total

32

59

0

0

9

17

0

0

31

57

39

72

Figure 19.

Antarctic krill sample of small ring net.
Figure 21.

Ice krill.

Figure 20.

Antarctic krill.
Figure 22.

of 19 m to 146 m, depth of sea bottom range was 178 m
to 5,240 m. The range of body length was from 12 mm to59 mm. The incubating Antarctic krill was sampled at two
stations in Area III-SE. Ice krill was sampled at a station in

Bigeye krill.

the Prydz Bay, distribution of surface water temperature
was 1.6°C. They were sampled at depths of 130 m, depthof sea bottom was 670 m. Bigeye krill were sampled atten stations, distribution of surface water temperature
29

Technical Reports of the Institute of Cetacean Research (2019)

Figure 23.

Antarctic silverﬁsh (Pleuragramma antarcticum).

Figure 24.

Myctophidae.

Comparison of IKMT and small ring net
Simultaneous samplings with the small ring net and
IKMT were conducted at seven stations by KY7. In threecases, Antarctic krill was sampled by both IKMT and small
ring net. However, for the other four cases, the resultsfrom both nets were not consistent. In the 2016/17 and2017/18 NEWREP-A, a total of seven cases of simultaneous sampling occurred, two cases were consistent for
both nets (Wada et al. 2017; 2018). These results indicatethat it is diﬃcult to collect representative krill samples
by the small ring net. However, the small ring net cancontribute to obtaining qualitative information on the
distribution of krill species and it requires less time incomparison to IKMT sampling.
Oceanographic observation
The oceanographic observation by CTD casting was
conducted at 144 stations by YS2 and KY7 (69 stations
in Area III-E, 42 stations in Area IV-W, 11 stations in the
Prydz Bay and 22 stations in Area IV-E, Table 2). The
seawater sampling was conducted at 16 stations at thesame locality where CTD castings were taken. Seven stations in Area III-E and ﬁve stations in Area IV-W, two stations in the Prydz Bay and two stations in Area IV-E were
sampled (Table 2). A total of 176 seawater samples weretaken then kept in clear bottles for salinity calibration.
For chlorophyll-a calibration samples were ﬁltered andstored with dimethylformamide.

ANALYSES OF DATA

Figure 25.

Copepoda.

was in the range of −1.4°C to 1.0°C. They were sampled at
depths of 35 m to 146 m, depth of sea bottom range was
2,100 m to 5,240 m. The range of body length was from
10 mm to 25 mm.

30

The main objective of krill and oceanographic surveys
was to estimate the abundance of Antarctic krill acoustically, and to obtain the length frequency distribution andmaturity stage of Antarctic krill in the survey area.
Quantitative Echosounder data is used for estimating
krill abundance. The software Echoview 9 (Echoview Software Pty. Ltd., Australia) is used for calculating backscattering of krill after noise removal. Estimate value of krill
abundance is obtained from this backscattering in eachresearch area. This estimate requires identiﬁcation of krill
species and body length obtained by the IKMT samplingand small net sampling.
The oceanographic data is used for identifying structure of ocean currents likely Upper Circumpolar Deep
Water, Lower Circumpolar Deep Water and Shelf Water
based on CTD data. These currents are assumed in relation to the distribution of krill and predators.
The analyses are being conducted by the ICR and several external research organizations.

Dedicated whale sighting vessels as a platform for krill and oceanographic research in the Indo-Pacific region of the Antarctic

ACKNOWLEDGEMENTS
I would like to thank the Government of Japan for providing support for this survey, and the captains and crew
members of YS2, YS3 and KY7 for their eﬀort at the ﬁeld.
I also thank several scientists that supported the designand development of the krill and oceanographic surveys.

REFERENCES
Buckland, S.T., Rexstad, E.A., Marques, T.A. and Oedekoven, C.S.
2015. Distance sampling: Methods and applications. Springer
International, Switzerland. 277 pp.
Commission for the Conservation of Antarctic Marine Living
Resources. 2011. The CCAMLR—Scientiﬁc observers manual(Observation guidelines and reference materials): 16.
Commission for the Conservation of Antarctic Marine Living
Resources. 2016. Report of the working group on Statistics,
Assessments and Modelling, June 2016: 3–4.
Demer, D.A., Berger, L., Bernasconi, M., Bethke, E., Bowswell,K., Chu, D., Domokos, R., Dunford, A., Fässler, S., Gauthier, S.,
Hufnagle, L.T., Jech, J.M., Bouﬀant, N., Dhaussy, A.L., Lurton,
X., Macaulay, G.J., Perrot, Y., Ryan, T., Stetter, S.P., Stienessen,S., Weber, T. and Williamson, N. 2015. Calibration of acoustic
instruments. ICES Cooperative Res. Rep. No. 326: 1–87.
Fujise, Y. and Pastene, L.A. 2018. Cetaceans as indicators ofhistorical and current changes in the Antarctic ecosystem.
Technical Reports of the Institute of Cetacean Research(TEREP-ICR) No.2: 1–13.
Hakamada, T. and Matsuoka, K. 2017. Sighting survey procedures for abundance estimates of large whales in JARPA and
JARPAII, and results for Antarctic minke whales. Technical
Reports of the Institute of Cetacean Research (TEREP-ICR)
No.1: 28–36.
International Whaling Commission. 2012. Requirements andguidelines for conducting surveys and analysing data within
the Revised Management Scheme. J. Cetacean Res. Manage.
(Suppl.) 13: 509–517.

Japan Meteorological Agency. 1999. Manual on oceanographic
observation part 1. Japan Meteorological Business Support
Center, Tokyo. 200 pp (in Japanese).
Laws, R.M. 1977. Seals and whales of the Southern Ocean.
Philos. Trans. R. Soc. Lond. B 279: 81–96.
Laws, R.M. 1985. The Ecology of the Southern Ocean. Am. Sci.
73: 26–40.
Matsuoka, K., Ensor, P., Hakamada, T., Shimada, H., Nishiwaki,S., Kasamatsu, F. and Kato, H. 2003. Overview of minke
whale sighting surveys conducted on IWC/IDCR and SOWER
Antarctic cruises from 1978/79 to 2000/01. J. Cetacean Res.
Manage. 5: 173–201.
Saito, H. 2007. Nihonkai Shuhen Kaiiki Ni Okeru Teiji Seitaikei
Monitoring Ni Okeru Keikoho Ni Yoru Chlorophyll-a Bunseki
Manual version 1d. Tohoku National Fisheries Res. Inst. (unpublished). 12 pp (in Japanese).
Simmonds, J. and MacLennan, D. 2005. Fisheries acoustics
theory and practice second edition. Blackwell Sci.: 326–328.
Trathan, P.N., Watkins, J.L., Murray, A.W.A., Brierley, A.S.,
Everson, I., Goss, C., Priddle, J., Reid, K., Ward, P., Hewitt,
R., Demer, D., Naganobu, M., Kawaguchi, S., Sushin, V.,
Kasatkina, S.M., Headley, S., Kim, S. and Pauly, T. 2001. The
CCAMLR-2000 krill synoptic survey: a description of the rationale and design. CCAMLR Sci. Vol. 8: 23 pp.
Wada, A., Konishi, K., Bansho, S., Kasai, H., Igarashi, Y. andTamura, T. 2017. Result of the krill and oceanographic survey under the NEWREP-A in the Antarctic in 2016/17. Paper
SC/67a/EM9 presented to the IWC Scientiﬁc Committee, May
2017 (unpublished). 9 pp. [Available from the IWC Secretariat].
Wada, A., Mogoe, T., Bansho, S., Kasai, H., Sasaki, Y. and Tamura,T. 2018. Result of the krill and oceanographic survey under the
NEWREP-A in the Antarctic in 2017/18. Paper SC/67b/EM5
presented to the IWC Scientiﬁc Committee, April 2018 (unpublished). 12 pp. [Available from the IWC Secretariat].
Wiebe, P.H., Ashjian, C.J., Gallager, S.M., Davis, C.S., Lawson,
G.L. and Copley, N.J. 2004. Using a high-powered strobe
light to increase the catch of Antarctic Krill. Mar. Biol. 144:
493–502.

31