SC/F16/JR31

Temporal trend of PCB levels in common minke whales fromthe western North Pacific for the period 2002-2014
GENTA YASUNAGA AND YOSHIHIRO FUJISEThe Institute of Cetacean Research, 4-5, Toyomi-cho, Chuo-ku, Tokyo, 104-0055, Japan.
Contact e-mail: yasunaga@cetacean.jp

ABSTRACTTo examine yearly changes of PCB in the western North Pacific, PCB concentrations in blubber of O-stock
mature males of common minke whales (Balaenoptera acutorostrata) from the western North Pacific, were
measured. Averages and standard deviations of PCB concentrations in blubber of minke whales from sub-area
7 (period 2002-2012), off Kushiro (period 2002-2014), off Sanriku (period 2003-2014), sub-areas 8 (period
2002-2009) and 9 (period 2002-2013) were 0.83±0.49, 0.63±0.41, 1.2±0.58, 1.0±0.75 and 0.59±0.34, ppm wetwt., respectively. Multiple linear regression analysis was carried out. Data included adjustment for confounders,sampling years, sampling longitude, latitude, sampling date, body length, blubber thickness and main preyspecies. No significant correlations between year and food items were observed for all areas. It is suggested
that PCB levels in minke whales from the western North Pacific were stable during 2002-2014.

KEYWORDS: COMMON MINKE WHALE; NORTH PACIFIC; PCB; MONITORINGINTRODUCTION
Pollutants bioaccumulate through the food web in the marine ecosystem. Because cetaceans are located at the top of theecosystem they are frequently used for monitoring the pollutants in the marine environment. They are mobile and longlived animals, and these characteristics mean that pollutants can be monitored in wide sea areas and integrated in some
way over time. Polychlorinated biphenyl (PCB) is man-made chemical that had been widely used throughout the worldin electrical equipments such as transformers and capacitors until the 1970s. In spite of the ban of production and usage
in the 1970s, PCB is still being released into the environment due to its lipophilic and highly persistent character.
Especially, top marine predators such as whales tend to accumulate PCB in their fatty tissues with growth (Tanabe et al.,
1981; Connell, 1988). The Japanese Whale Research Programme under Special Permit in the North Pacific Phase II(JARPNII) was designed so that samples can be obtained for investigating the quantitative behaviour and fate of PCB in
the marine environment.
In the western North Pacific, yearly change of PCB concentrations in marine mammals have been reported previously.
Tanabe et al., (1994) reported temporal variation of PCB in female northern fur seal. The concentration showed amaximum in around 1976 and then decreased until 1988. Aono et al., (1997) examined PCB in blubber of common
minke whales (Balaenoptera acutorostrata) from the western North Pacific between 1987 and 1994. No trend in theconcentration was observed in this period. Kajiwara et al. (2004) reported that the PCB concentrations andcompositions were steady-stable in fat tissues of female northern fur seals collected in the period 1972-1998 from theJapanese Pacific coast, suggesting a continuous input of PCB into the marine environment in significant quantities.
In the 2009 review workshop, Yasunaga and Fujise (2009) presented a study on temporal changes of PCB
concentrations in blubber samples of common minke, sei (B. borealis) and Bryde’s (B. edeni) whales from the western
North Pacific. Yearly changes of PCB concentrations were not observed in minke, sei and Bryde’s whales in the
research period 2002-2007, whereas previous studies reported temporal variation of PCB concentrations in the northern
fur seals (Tanabe et al., 1994; Kajiwara et al., 2004) and minke whales (Aono et al., 1997) from the western North
Pacific with a maximum in 1976 and a decreasing trend until approximately 2000. These results lead us to propose thefollowing working hypothesis. PCB concentrations in baleen whales from the western North Pacific decreased until theend of the decade of the 1990’s and then they have stabilized since the 2000’s.
This study examines concentrations and yearly changes of PCB concentrations in O-stock mature male common minke
whales. Further, body length, blubber thickness, stomach content and sexual maturity information obtained during
JARPN and JARPNII surveys are considered to assist in the interpretation of factors affecting PCB concentrations.

1

MATERIALS AND METHODS
Samples and sampling method
Blubber tissues of mature males of the common minke whales (Okhotsk Sea-West Pacific stock) from sub-area 7, off
Sanriku, off Kushiro, sub-areas 8 and 9 were collected by JARPNII researchers in the surveys conducted in the period
from 2002 to 2015 (Fig. 1). Table 1 shows the sample sizes, and average of body length and blubber thickness of thewhales sampled, by sub-area and survey. The blubber samples were frozen and stored at -20˚C until chemical analysis.

Laboratory analysis
The blubber samples were sent to the Japan Food Research Laboratories (Tokyo, Japan) for PCB analyses. Analyses
were performed according to the public analytical method of Japan (Japan Ministry of Welfare, 1972).

Statistical analysis
The yearly changes of PCB concentrations in whales were assessed by multiple linear regression in the context of otherfactors in whales (R Development Core Team, 2006). The following independent variables: “sampling year”, “samplingdate”, “sampling latitude”, “sampling longitude”, “body length”, “blubber thickness” and “main prey item” wereallowed, and all parameters except for main prey item were logarithmic transformed. Categorical parameters of main
prey items used in the analyses were the following: sub-area 7 minke whale (Japanese anchovy: Engraulis japonicus,
Euphausiids, Japanese flying squid: Todarodes pacificus, mackerel: Scomber japonicus, Japanese sardine: Sardinops
melanostictus, Pacific saury: Cololabis saira and Walleye Pollock: Theragra chalcogramma); off Kushiro and off
Sanriku common minke whale (None); sub-area 8 minke whale (anchovy, copepods, euphausiids, Japanese flying squid,
mackerel and Pacific saury); sub-area 9 minke whale (anchovy, Atka mackerel: Pleurogrammus monopterygius,
copepods, euphausiids, mackerel, armhook squid: Berryteuthis anonychus, oceanic lightfish: Vinciguerria nimbaria,
Pacific pomfret: Brama japonica, salmonids, Pacific saury). A p value of less than 0.05 was considered to indicate
statistical significance in all tests. The statistical analyses were performed using the free software R, version 3.2.0.
RESULTS
Table 1 shows the PCB concentrations in blubber of O stock mature males of minke whales from sub-area 7, off
Kushiro, off Sanriku, sub-areas 8 and 9. Averages and standard deviations of PCB concentrations in blubber samples ofminke whales were 0.83±0.49, 0.63±0.41, 1.2±0.58, 1.0±0.75 and 0.59±0.34, ppm wet wt., respectively. Plots of total
PCB concentrations against their sampling year are shown for minke whales during 2002 to 2014 in Figs. 2a-2e for eachof the different sub-areas and two sea areas.
To examine the factors affecting PCB concentrations in minke, multiple regression linear analyses were conducted.
The results for minke whales in sub-area 7, off Kushiro, off Sanriku, sub-areas 8 and 9 are shown in Tables 2, 3, 4, 5
and 6, respectively. Regression models were significant for all areas, except for off Sanriku. Consequently, body length(+) and date (-) were significantly associated in PCB concentrations in minke whales from sub-area 7 (Table 2), bodylength (+), blubber thickness (-) and date (-) was significantly associated those from off Kushiro (Table 3), and bodylength (+) was significantly associated those from sub-areas 8 and 9 (Tables 5 and 6).
DISCUSSION
In the multiple regression analyses of PCB concentrations in minke whales, body length was significantly associated for
positive covariance in the all areas, and blubber thickness and sampling date were significantly associated for negative
covariance in some areas. One reason for this is a strong positive association between persistent PCB concentrations
and age or body length in marine mammals (Aguilar et al., 1999; Tanabe et al., 1987). Furthermore, negative
correlations between PCB concentrations and sampling date or blubber thickness in minke whales were observed,
because PCB concentrations may be diluted by rapidly increasing of body weight and fat volume in a feeding season.
On the other hand, food items were not significantly associated in these analyses, whereas they were significantly
associated in the THg analyses of minke whales from sub-areas 7 and 9 (Yasunaga and Fujise, 2016). This is attributed
to higher persistence of PCB in a whale body as compared to Hg. By considering the covariates, PCB concentrations
stabilized in minke whales from the western North Pacific during 2002-2014.
There are some reports of yearly changes of PCB concentrations in the western North Pacific using marine mammals
as biological indicator. Tanabe et al., (1994) reported temporal variation of PCB with a maximum in 1976 and adecreasing trend until 1988 in female northern fur seal. Kajiwara et al. (2004) reported that PCB concentrations in fat
tissues of female northern fur seals collected from off Sanriku coast in the period 1972 - 1998 continually decreased
since the early 1980s. Aono et al., (1997) reported that the PCB concentrations in blubber of common minke whales
from the western North Pacific (offshore) between 1987 (1.5-3.0 ppm wet wt.) and 1994 (0.62-3.1 ppm wet wt.) weresimilar, whereas these concentrations were lower than those in the present study during 2002-2014. These results
indicate that ban of usage of PCB in developed nations after the 1970s has influenced on PCB concentrations in whales
2SC/F16/JR31
in the western North Pacific. On the other hand, Kajiwara et al. (2008) reported that PCB concentrations in melonheaded whales from the coast of Japan in 2001/02 were significantly lower than those in 1982, whereas there was no
significant difference between those in 2001/02 and in 2006. Isobe et al. (2009) reported that there were no significant
differences of PCB concentrations in striped dolphins from the coast of Japan among samples from 1978, 1979, 1986
and 1992. These observations indicate that the rate of degradation and deposit of PCB in this area would have been slow
since approximately 2000’ and/or an exiguous PCB existing in the environment would continuously input into themarine environment near the Japanese coast. Our findings support the hypothesis from the 2009 JARPNII review, that
“The PCB concentrations in marine mammals in coastal Japan had continually decreased until the end of 1990’s, and it
has stabilized since at least from 2002 (Yasunaga and Fujise, 2009)”.
REFERENCES
Aguilar, A., Borrell, A. and Pastor, T. 1999. Biological factors affecting variability of persistent pollutant levels incetaceans. J. Cetacean Res. Manage., (Special Issue 1) 83-116.
Aono, S., Tanabe, S., Fujise, Y., Kato, H. and Tatsukawa, R. 1997. Persistent organochlorines in minke whale(Balaenoptera acutorostrata) and their prey species from the Antarctic and the North Pacific. Environ. Pollut.
98:81-89.
Japan Ministry of Welfare. 1972. Analytical Method of PCBs, Tokyo, Japan (in Japanese).
Connell, D.W. 1988. Bioaccumulation behavior of persistent organic chemicals with aquatic organisms. Rev. Environ.
Contam. Toxicol. 102:117-154.
Isobe, T., Ochi, Y., Ramu, K., Yamamoto, T., Tajima, Y., Yamada, T.K., Amano, M., Miyazaki, N., Takahashi, S. andTanabe, S. 2009. Organohalogen contaminants in striped dolphins (Stenella coeruleoalba) from Japan: Present
contamination status, body distribution and temporal trends (1978–2003). Mar. Pollut. Bull. 58:396-401.
Japan Ministry of Welfare. 1972. Analytical Method of PCBs, Tokyo, Japan (in Japanese).
Kajiwara, N., Ueno, D., Takahashi, A., Baba, N. and Tanabe, S. 2004. Polybrominated diphenyl ethers andorganochlorines in archived northern fur seal samples from the Pacific coast of Japan, 1972-1998. Environ. Sci.
Technol. 38:3804-9.
Kajiwara, N., Kamikawa, S., Amano, M., Hyano, A., Yamada, T.K., Miyazaki, N. and Tanabe, S. 2008.
Polybrominated diphenyl ethers (PBDEs) and organochlorines in melon-headed whales, Peponocephala electra,
mass stranded along the Japanese coasts: Maternal transfer and temporal trend. Environ. Pollut. 156:106-114.
R Development Core Team 2006. R: A language and environment for statistical computing. R Foundation for StatisticalComputing, Vienna, Austria. ISBN 3-900051-07-0, URL http://www.R-project.org.
Tanabe, S., Tatsukawa, R., Tanaka, H., Maruyama, K., Miyazaki, N. and Fujiyama, T. 1981. Distribution and total
burdens of chlorinated hydrocarbons in bodies of striped dolphins (Stenella coeruleoalba). Agri. Biol. Chem.
45:2569-2578.
Tanabe, S., Loganathan, B. G., Subramanian, A. N. and Tatsukawa, R. 1987. Organochlorine residues in short-finned
pilot whale. Mar. Pollut. Bull., 18:561-563.
Tanabe, S., Sung, J. K., Choi, D. Y., Baba, N., Kiyota, M., Yoshida, K. and Tatsukawa, R. 1994. Persistentorganochlorine residues in northern fur seal from the Pacific coast of Japan since 1971. Environ. Pollut. 85:305314.
Yasunaga, G. and Fujise, Y. 2009. Temporal trends of PCB levels in baleen whales and environmental samples from thewestern North Pacific. Paper SC/J09/JR23 presented to the JARPNII Review Workshop, Tokyo, January 2009
(unpublished). 14pp.
Yasunaga, G. and Fujise, Y. 2016. Temporal trend of total Hg levels in baleen whales and their items based on
JARPNII data for the period 1994-2014. Paper SC/F16/JR31 presented to the JARPNII Review Workshop, Tokyo,
February 2016 (unpublished). 14pp.

3

Table 1. Biological data and PCB levels in blubber of common minke whales (males) from the western
North Pacific during 1994 and 2014
subarea
7

year

2002
2003
2004
2005
2006
2007
2009
2011
2012
total
Kushiro
2002
2004
2005
2006
2007
2008
2009
2010
2011spring
2011autumn
2012
2013
2014
total
Sanriku
2003
2005
2006
2007
2008
2009
2010
2012
2013
2014
total
8
2002
2003
2005
2006
2007
2008
2009
total
9
2002
2003
2004
2005
2006
2007
2008
2009
2010
2013
total

maturitynmaturematurematurematurematurematurematurematuremature

33
11
6
17
16
41
11
23
19
177
14
23
25
10
14
5
6
3
4
10
5
23
10
152
8
3
6
10
3
1
5
2
2
2
42
5
27
2
24
10
3
6
77
21
28
50
25
16
4
36
5
9
3
197

maturematurematurematurematurematurematurematurematurematurematurematurematurematurematurematurematurematurematurematurematurematurematurematurematurematurematurematurematurematurematurematurematurematurematurematurematurematurematuremature

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body length(m)7.52 ± 0.27
7.42 ± 0.40
7.56 ± 0.21
7.51 ± 0.23
7.39 ± 0.39
7.47 ± 0.26
7.71 ± 0.26
7.47 ± 0.34
7.37 ± 0.34
7.48 ± 0.31
7.22 ± 0.34
7.43 ± 0.24
7.44 ± 0.32
7.52 ± 0.29
7.33 ± 0.59
7.26 ± 0.21
7.54 ± 0.37
7.49 ± 0.21
7.40 ± 0.41
7.26 ± 0.37
7.48 ± 0.21
7.33 ± 0.35
7.33 ± 0.28
7.38 ± 0.35
7.10 ± 0.35
7.27 ± 0.13
7.24 ± 0.32
7.50 ± 0.30
7.49 ± 0.32
6.85 ±
7.32 ± 0.24
7.31 ±
7.52 ±
7.38 ± 0.39
7.32 ± 0.32
7.71 ± 0.21
7.50 ± 0.24
7.54 ±
7.51 ± 0.26
7.55 ± 0.26
7.52 ± 0.05
7.23 ± 0.34
7.51 ± 0.26
7.55 ± 0.21
7.50 ± 0.32
7.47 ± 0.21
7.49 ± 0.29
7.56 ± 0.30
7.56 ± 0.20
7.45 ± 0.26
7.41 ± 0.41
7.66 ± 0.23
7.59 ± 0.22
7.50 ± 0.26

PCB in blubber
blubber thickness(cm)(ppm wet wt.)
） (3.7 ± 0.8
） (0.74 ± 0.31
） (2.4 ± 0.5
） (1.38 ± 0.79
） (4.1 ± 0.6
） (0.42 ± 0.11
） (3.3 ± 0.9
） (0.83 ± 0.44
） (2.4 ± 0.7
） (0.87 ± 0.40
） (3.0 ± 0.7
） (0.75 ± 0.32
） (3.2 ± 0.7
） (0.81 ± 0.48
） (3.5 ± 0.6
） (0.60 ± 0.30
） (2.6 ± 0.4
） (1.24 ± 0.71
） (3.1 ± 0.8
） (0.83 ± 0.49
） (4.3 ± 1.0
） (0.64 ± 0.26
） (4.2 ± 0.6
） (0.50 ± 0.22
） (3.5 ± 0.6
） (0.58 ± 0.18
） (4.4 ± 0.8
） (0.72 ± 0.54
） (4.1 ± 0.8
） (0.67 ± 0.30
） (4.3 ± 1.0
） (0.58 ± 0.31
） (4.3 ± 0.4
） (0.84 ± 0.35
） (3.8 ± 0.4
） (1.00 ± 0.45
） (3.2 ± 0.6
） (1.51 ± 1.20
） (0.53 ± 0.26
） (4.4 ± 1.0
） (0.51 ± 0.15
） (5.0 ± 0.7） (5.0 ± 0.9
） (0.56 ± 0.36
） (5.0 ± 0.8
） (0.69 ± 0.77
） (4.3 ± 0.9
） (0.63 ± 0.41
） (2.9 ± 0.5
） (0.82 ± 0.14） (2.5 ± 0.3
） (1.10 ± 0.26
） (2.8 ± 0.2
） (1.48 ± 1.00
） (2.5 ± 0.4
） (1.11 ± 0.53
） (3.2 ± 0.3
） (1.55 ± 0.75
） (
2.8 ±
） (
1.60 ±） (3.1 ± 0.6
） (1.20 ± 0.51
） (
3.4 ±
） (
1.16 ±
） (
3.5 ±
） (
1.09 ±） (2.7 ± 0.3
） (1.13 ± 0.25
） (2.8 ± 0.5
） (1.16 ± 0.58
） (3.2 ± 0.6
） (0.87 ± 0.43
） (2.4 ± 0.4
） (1.13 ± 0.86
） (
2.2 ±
） (
1.82 ±） (2.9 ± 0.6
） (0.99 ± 0.77
） (2.3 ± 0.4
） (0.83 ± 0.38
） (2.7 ± 0.4
） (0.86 ± 0.36
） (3.2 ± 0.6
） (0.65 ± 0.51
） (2.6 ± 0.6
） (1.00 ± 0.75
） (2.9 ± 0.6
） (0.69 ± 0.25
） (2.9 ± 0.6
） (0.56 ± 0.21
） (3.9 ± 0.7
） (0.46 ± 0.23
） (3.5 ± 0.6
） (0.62 ± 0.44
） (3.4 ± 0.6
） (0.62 ± 0.43
） (0.76 ± 0.44
） (2.2 ± 0.3
） (0.58 ± 0.36
） (3.1 ± 0.7
） (3.0 ± 0.8
） (0.72 ± 0.49
） (3.2 ± 0.5
） (0.72 ± 0.61
） (4.0 ± 1.3
） (0.93 ± 0.19
） (3.3 ± 0.8
） (0.59 ± 0.34

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SC/F16/JR31
Table 2. Results of multiple linear regression analyses with "PCB levels in blubber of common minke
whales from subarea 7" as the dependent variable.
a) Model of regression
1

R2
0.489

R2 '
0.447

b) Analysis of Variance Table
Model
Regression
Residual

DF
158
158

SE
0.463

B
-46.166
4.065
0.072
1.475
5.013
-1.649315.173315.393315.341315.236315.197315.473315.223SE
30.288
0.920
0.186
2.031
3.681
0.371
236.333
236.322236.335
236.354236.391236.318
236.356

Model

F value
11.61

P value<0.001

T
-1.52
4.42
0.39
0.73
1.36
-4.44
1.33
1.34
1.33
1.33
1.33
1.34
1.33

P value
0.129<0.001
0.700
0.469
0.175
<0.001
0.184
0.184
0.184
0.184
0.184
0.184
0.184

c) Variables
Model
Year
Body length
Blubber thickness
longitude
latitude
Date
MainPrey_Anchovy
MainPrey_Euphausiids
MainPrey_JFSquid
MainPrey_Mackerel
MainPrey_Sardine
MainPrey_Saury
MainPrey_WalleyePollock

Table 3. Results of multiple linear regression analyses with "PCB levels in blubber of common minke
whales from off Kushiro" as the dependent variable.
a) Model of regression
1

R2
0.643

R2 '
0.628

b) Analysis of Variance Table
Model
Regression
Residual

DF
146
146

SE
0.477

B
-20.402
1.902-0.4610.654
30.495-1.193

SE
13.8770.798
0.180
15.22923.104
0.404

Model

F value
43.74

P value<0.001

T
-1.47
2.38
-2.56
0.04
1.32
-2.95

P value
0.144
<0.05
<0.05
0.966
0.189
<0.01

c) Variables
Model
Year
Body length
Blubber thickness
latitudelongitude
Date

5Table 4. Results of multiple linear regression analyses with "PCB levels in blubber of common minke
whales from off Sanriku" as the dependent variable.
a) Model of regression
1

R2
0.049

R2 '
-0.109b) Analysis of Variance Table
Model
Regression
Residual

DF
36
36

SE

Model

F value
0.31118

P value
0.9267

0.499

Table 5. Results of multiple linear regression analyses with "PCB levels in blubber of common minke
whales from subarea 8" as the dependent variable.
a) Model of regression
1

R2
0.480

R2 '
0.379

b) Analysis of Variance Table
Model
Regression
Residual

DF
62
62

SE
0.554

B
13.12611.054-0.156-3.991-1.454
1.009-101.730-101.963-102.162-102.719-102.779-102.085

SE
75.277
2.124
0.366
3.919
6.661
1.362
569.280
569.408569.370569.154569.421569.316Model

F value
4.76

P value<0.001

T
0.17
5.20
-0.43
-1.02
-0.22
0.74
-0.18
-0.18
-0.18
-0.18
-0.18
-0.18

P value
0.862<0.001
0.671
0.313
0.828
0.462
0.859
0.858
0.858
0.857
0.857
0.858

c) Variables
Model
Year
Body length
Blubber thickness
latitudelongitude
Date
MainPrey_Anchovy
MainPrey_Copepods
MainPrey_Euphausiids
MainPrey_JFSquid
MainPrey_Mackerel
MainPrey_Saury

6

SC/F16/JR31
Table 6. Results of multiple linear regression analyses with "PCB levels in blubber of common minke
whales from subarea 9" as the dependent variable.
a) Model of regression
1

R2
0.667

R2 '
0.639

b) Analysis of Variance Table
Model
Regression
Residual

DF
179
179

SE
0.525

B
26.5533.833
0.018-2.180-2.6000.332-189.418-190.017-189.702-189.313-189.234-189.399-190.059-189.368-189.525

SE
34.443
1.114
0.190
1.515
1.816
0.690
259.890259.851259.908259.845259.937
259.857
259.912259.890259.883

Model

F value
23.9

P value<0.001

T
0.77
3.44
0.09
-1.44
-1.43
0.48
-0.73
-0.73
-0.73
-0.73
-0.73
-0.73
-0.73
-0.73
-0.73

P value
0.441761<0.001
0.925
0.152
0.154
0.631475
0.467051
0.46558
0.466416
0.467223
0.467565
0.467041
0.465587
0.467171
0.466789c) Variables
Model
Year
Body length
Blubber thickness
latitudelongitude
Date
MainPrey_Anchovy
MainPrey_AtkaMackerel
MainPrey_Copepods
MainPrey_Euphausiids
MainPrey_Mackerel
MainPrey_MAFSquid
MainPrey_OceanicLightfish
MainPrey_PacificPomfret
MainPrey_Saury

Off Kushiro

Off Sanriku

Figure 1. Sub-areas surveyed by the JARPNII research. Sub-areas based on IWC (1994), excluding the EEZ of Russia

7

PCB levels in blubber (ppm wet)mature male of common minke whale, sub-area 7
4.0
3.0
2.0
1.0
0.0

2001

2003

2005

2007
year

2009

2011

2013

Figure 2a. Simple plots of PCB concentrations in blubber of common minke whales (mature males, O-stock) in sub-area
7 during the period 2002-2012

PCB levels in blubber (ppm wet)mature male of common minke whale, Kushiro
4.0
3.0
2.0
1.0
0.0

2001

2003

2005

2007
year

2009

2011

2013

Figure 2b. Simple plots of PCB concentrations in blubber of common minke whales (mature males, O-stock) in off
Kushiro during the period 2002-2014

PCB levels in blubber (ppm wet)mature male of common minke whale, Sanriku
4.0
3.0
2.0
1.0
0.0

2001

2003

2005

2007
year

2009

2011

2013

Figure 2c. Simple plots of PCB concentrations in blubber of common minke whales (mature males, O-stock) in off
Sanriku during the period 2002-20148

SC/F16/JR31

PCB levels in blubber (ppm wet)mature male of common minke whale, sub-area 8
4.0
3.0
2.0
1.0
0.0

2001

2003

2005

2007
year

2009

2011

2013

Figure 2d. Simple plots of PCB concentrations in blubber of common minke whales (mature males, O-stock) in subarea 8 during the period 2002-2009

PCB levels in blubber (ppm wet)mature male of common minke whale, sub-area 9
4.0
3.0
2.0
1.0
0.0

2001

2003

2005

2007
year

2009

2011

2013

Figure 2e. Simple plots of PCB concentrations in blubber of common minke whales (mature males, O-stock) in sub-area
9 during the period 2002-20139