SC59/O13
SOME INITIAL PROGRESS ON THE ECOSYSTEM MODELLING OF THE JARPNⅡ SURVEY AREA
USING ECOPATH-WITH-ECOSIM

MITSUYO MORI AND TAKASHI HAKAMADAThe Institute of Cetacean Research, 4-5 Toyomi-cho, Chuo-ku, Tokyo, 104-0055, Japan
Contact e-mail: mori@cetacean.jp
ABSTRACT

In order to evaluate the possible impact of whales (minke whales, bryde’s whales, sei whales and sperm whales)
migrating to the JARPNⅡsurvey area on Japanese commercially important fisheries resources, an initial ecosystemmodel of the JARPNⅡsurvey area is built using the Ecopath-with-Ecosim software, and is based on the newly
collected provisional data sets obtained from the JARPNⅡsurvey. As for an initial test run, the impact of no
harvesting of the minke whales for the coming 50 years on Japanese commercially important fishes was made. Whenrunning the harvesting scenario, uncertainties in the functional response curve and the trophic flow of the ecosystem
are considered. In this test run, increase in minke whale biomass has some effect on pacific saury, though it has hardly
any effect on other species considered in the model. The magnitude of the impact of the change in biomass of minke
whales on pacific saury varies by the functional response curve assumed for minke whales and the magnitude of thetrophic flow and the combination of the two. It is predicted that the biomass of pacific saury may decrease inmaximum about 36% in the coming 50 years compared to the current level due to increase in predation pressure by theminke whales when this species were not harvested for the coming 50 years. Further work will take into account theeffect of the equilibrium condition in Ecopath, will try to fit the model to available time-series data, and will consider
the effect of quasi-decadal alternations in dominant species replacement (may be due to environmental forcing).

KEYWORD ECOPATH-WITH-ECOSIM, JARPN ⅡSURVEY, ECOSYSTEM MODELLING, MINKE WHALE, PACIFIC SAURY

INTRODUCTION
This paper introduces some initial progress on the ecosystem modelling of the JARPNⅡsurvey area using Ecopathwith-Ecosim software (Christensen et al. 2005), and is based on the newly collected provisional data sets obtained fromthe JARPNⅡsurvey. The main objectives of the study are:1)

Evaluate the possible impact of whales migrating to the JARPNⅡsurvey area on Japanese commercially
important fisheries resources, and2)

Estimate the difference between the MSY of a species calculated from single-species assessments to those
calculated from multi-species assessment.

MODEL AND DATA TO BE USEDThe model used is the Ecopath with Ecosim Ver.5.1（Christensen et al. 2005）, and the time-scale modelled is one
year. The area to be modelled is the off-shore areas of sub-area 7, and sub-areas 8 and 9 of JARPNⅡsurvey areas (total
area to be modelled is 2,775,043km2) . The number of species considered is 30 species and are shown in Table 1a.

The data used in the model are shown in Tables 1a, 1b and 1c (an Appendix which explains the references/sources ofdata is in progress). Essentially, data on biomass, production, consumption, catch and diet-composition is required foreach species, and most of these data for whales are obtained from the JARPNⅡsurvey.
METHODS
By using Ecopath, first a mass-balance model which reflects the current situation of the ecosystem (about from year
2000 to 2006) is built, and the connectivity of the species and the possible qualitative impact of an increase in one
species may have on another is examined using mixed trophic-impact analysis.

Next by using Ecosim, the possible

impact of whales on their prey species, especially those that are commercially important for Japanese fisheries isevaluated. As for initial test runs, the impact of the following harvesting scenarios for minke whales and their main
preys is evaluated:
Harvesting scenarioⅰ）No catch for the coming 50 years.
Harvesting scenario ⅱ）Double the size of the current catch for the coming 50 years.
When running the harvesting scenarios, the following three uncertainties are considered:
1) Uncertainties in the in-put parameters of Ecopath.
2) Uncertainties in the functional response curve (e.g. Hollying TypeⅠ, Ⅱ, Ⅲ functional response).
3) Uncertainties in the trophic follow (e.g. top-down or bottom-up control).
For the various functional response curves (Hollying TypeⅠ, Ⅱ and Ⅲ), the parameter settings are as in the
Appendix of Mackinson et al. (2003). Also an additional version of a Type Ⅲ functional response curve (called “TypeⅢ+ other”) is assumed. The difference in this and the usual Type Ⅲ functional response curve is that an additional
assumption is made that the changes in the time spent foraging by a species proportionally affect their exposure to othersources of mortality that are not explicitly modelled, such as disease, starvation, collisions, or predation not accountedfor (Mackinson et al. 2003).
The trophic flow in Ecosim is controlled by the vulnerability parameter (v). Low v means that the species is lessvulnerable to its predator (bottom-up control) and high v means top-down control. If v is proportional to its trophic
level (TL), it means that the lower trophic level species have more places to hide (thus less vulnerable to predation)compared to those of the higher trophic level species.
The difference between the MSY of a species calculated from single-species assessments to those calculated frommulti-species assessment is estimated using the already developed routine in Ecosim.

PRESENT STATUS OF THE STUDY
1．Building a mass-balanced Ecopath model
At the first stage of the mass-balance model development, ecotrophic efficiency (EE) (EE: proportion of its productionused by consumption or harvesting) for some species considered in Table 1a exceeded 1. If EE>1, this means that the
species is harvested or consumed more than its production. Thus, by increasing the biomass or production of thespecies, or by reducing the predation mortality of the species, the parameters were adjusted to give a mass-balanced
model. This was achieved manually by considering the level of uncertainty of each in-put parameter shown in Table 1a.
2For most of the species that showed EE>1, this problem was solved by increasing the biomass of the species, which was
the most uncertain parameter. The resultant mass-balanced model and its estimated parameters are shown in Table 3.
Figure 1 describes the food-web assumed in the model and the trophic level of each species calculated using Ecopath.
Figure 2 shows the effect of a short-term increase in biomass of a species may have on another suggested by the outputof Ecopath under the assumptions examined. The species on the vertical axis shows the species that give impact, andthe species on the horizontal axis shows those that receive the impact. Upward bars represent positive impact, anddownward bars represent negative impact. For example, Figure 2 indicates that a short-term increase in the biomass of
pacific saury has positive impact on minke whales, while short-term increase in the biomass of anchovy has lesspositive impact on minke whales compared to those on bryde’s whales or skipjack tuna. Thus by utilizing Figure2, one
can qualitatively evaluate the relative impact of an increase in one species may have on another.
2．ECOSIM calculation
Table 4 shows output for the harvesting scenario, which no catch is assumed for minke whales for the coming 50 years(catch for other species are assumed same as the current level). The recent main preys of minke whales are pacificsaury and anchovy (see the diet composition in Table 1b). In this test run, increase in minke whale biomass had someeffect on pacific saury though it had hardly any effect on other species, thus in Table 4, only the relative change inbiomass for minke whales and pacific saury are shown. The magnitude of the impact of the change in biomass ofminke whales on pacific saury varies by the functional response assumed for minke whales and the magnitude of thetrophic flow (controlled by the vulnerability parameter (v) in Ecosim) and the combination of the two. Largest impactof minke whales on pacific saury was found when the vulnerability of the species was assumed to be proportional to thetrophic level, and when “Type III + other” functional response curve was assumed. The magnitude of the effectincreased as year accumulates, and in 50 years, it was predicted that the biomass of pacific saury may decrease inmaximum about 36% compared to the current level due to increase in predation pressure by the minke whales.

FUTURE WORK
Priority matters to be considered in future are:1) the equilibrium condition assumed in Ecopath,2) try fitting the model to available time-series data (and let v be estimated from the fit of the model),3) effect of quasi-decadal alternations in dominant species replacement (may be due to environmental forcing) andprey switching by whales, and
4) revision of some in-put data due to updated information (e.g. diet composition of northern fur seals, split anchovy
into immature and mature states etc.). An Appendix which describes all the references/sources of the in-put data
will be prepared in due course.
REFERENCES
Christensen, V., Walters, C. J., and Pauly, D. 2005. Ecopath with Ecosim: a User’s Guide. Fisheries Centre, Universityof British Columbia, Vancouver. November 2005 edition, 154p. (available onlie at www.ecopath.org)
Mackinson, S., Blanchard, J. L., Pinnegar, J. K. and Scott, R. 2003. Consequences of alternative functional response
formulations in models exploring whale-fishery interactions. Marine mammal Science, 19 (4): 661-681.
3

Table1a．In-put parameters of B, P/B, Q/B used in the Ecopath model (the color of each cells reflect the reliability ofthe data – see Table 2 for the definition of the colors used; essentially, if the color is more towards red it means thatthe data is more reliable. Where as if the color is more towards light-blue it means that the data is less reliable).
Q/B for the whales are mainly obtained from the JARPNⅡsurvey.

Species
1 Minke whale
2 Bryde's whale
3 Sei whale
4 Other baleen whales
5 Sperm whale
6 Baird's beaked whale
7 Short-finned pilot whale
8 Cuvier's beaked whale

Habitat area (fraction)
1
1
1
1
1
1
1
1

Biomass inhab.area(t/km2)
0.019
0.016
0.030
0.068
0.342
0.025
0.014
0.014

Other toothed whales
9
10 Northern fur seal
11 Marine birds
12 Albacore juveniles
13 Sword fish
14 Skipjack tuna
15 Blue shark
16 Salmon shark
17 Lanternfish
18 Neon flying squid
19 surface-mid water squid
20 deep sea squid
21 Mackerel
22 Pacific pomfret
23 Sardine
24 Anchovy
25 Pacific saury
26 Phytoplankton
27 Euphausiids
28 Copepods eaten by whales
29 Other Copepods
30 Detritus

1

0.038

0.10

11.32

1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1

0.001
0.004
0.036
0.001
0.036
0.014
0.013
7.207
0.144
0.330

0.24
0.10
0.35
0.60
2.90
0.33
0.33
2.34
2.56
2.56
2.56
1.07
0.75
1.50
1.53
0.72
194.36
11.12
5
5
-

20.30
54.57
1.94
2.05
20.00
2.20
3.65
14.97
21.60
21.60
21.60
7.15
3.75
10.00
7.50
4.80
12.05
10.00
10.00
-

0.252
0.053
0.047
1.081
1.694
26.58
1.982
21.30
21.30
132.92

4

Consumpti
Production/bi on/biomas Ecotrophic
omass (/year) s (/year) efficiency
0.10
5.20
0.09
4.38
0.06
4.16
0.06
3.90
0.10
4.20
0.11
5.53
0.10
7.42
0.10
7.06

0.95

Table 1b. Diet composition matrix used in the Ecopath model (the color of each cells reflect the reliability of the data – see Table 2 for the definition of the colors used; essentially,
if the color is more towards red it means that the data is more reliable. Where as if the color is more towards light-blue it means that the data is less reliable). Diet composition for
the whales are mainly obtained from the JARPN Ⅱsurvey.
Prey /Predator
Species
1 Minke whale
2 Bryde's whale
3 Sei whale
4 Other baleen whales
5 Sperm whale
6 Baird's beaked whale
7 Short-finned pilot whale
8 Cuvier's beaked whale

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

9 Other toothed whales
10 Northern fur seal
11 Marine birds
12 Albacore juveniles
13 Sword fish group ?
14 Skipjack tuna
15 Blue shark
16 Salmon shark
17 Lanternfish
0.1 0.05 0.1 0.12 0.1 0.19 0.01
0.02
0.28 0.2 0.2 0.02 0.03
18 Neon flying squid
0.11 0.01 0.1 0.2 0.13 0.14 0.14
0.35
0.12
0.01
0.01 0.04
19 surface-mid water squid
0.02
0.07 0.13 0.1 0.2 0.13 0.14 0.16 0.15 0.24 0.05 0.2 0.81
0.27 0.2 0.2 0.02 0.47
20 deep water squid
0.81 0.18 0.2 0.2 0.13
0.15
0.55 0.04
0.2
0.01 0.22
21 Mackerel
0.01
0.2 0.05 0.1 0.12 0.1
22 Pacific pomfret
0.2 0.05 0.1 0.12 0.1
0.05
0.07
23 Sardine
0.03 0.05 0.1 0.12 0.1
0.02
24 Anchovy
0.32 0.59 0.47 0.05
0.01 0.04 0.05 0.1 0.12 0.1 0.49
0.82 0.01
0.15 0.4 0.4 0.10 0.01
25 Pacific saury
0.35
0.05 0.05
0.03 0.05 0.1 0.12 0.1
0.02 0.03
26 Phytoplankton
0.70
27 Euphausiids
0.17 0.35 0.23 0.65
0.1 0.01
0.1 0.07
0.09
0.24 0.01 0.2 0.2 0.5 0.03
0.2 0.1
28 Copepods eaten by whales
0.24 0.26
0.18
0.15
0.15 0.4 0.45
29 Other Copepods
0.36
0.15
0.15 0.4 0.45
30 Detritus
Import0.14 0.05 0.01
0.01 0.67
0.1 0.2 0.04 0.03 0.15 0.22 0.08
0.17
Sum
1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00

5

26

27

28

29

0.12 0.26 0.26
0.09
0.09
0.7 0.74 0.74
1.00 1.00 1.00

Table 1c. Catch data used in the Ecopath model (the color of each cells reflect the reliability of the data – see Table 2
for the definition of the colors used; essentially, if the color is more towards red it means that the data is more reliable.
Where as if the color is more towards light-blue it means that the data is less reliable).

Species
1 Minke whale
2 Brydes whale
3 Sei whale
4 Other baleen whales
5 Sperm whale
6 Baird's beaked whale
7 Short-finned pilot whale

Whaling
2(t/km /year)
0.00020.00030.000406.84674E-05
0.00035.98189E-06

8 Cuvier's beaked whale0

9 Other toothed whales
10 Northern fur seal
11 Marine birds
12 Albacore juveniles
13 Sword fish group ?
14 Skipjack tuna
15 Blue shark
16 Salmon shark
17 Lanternfish
18 Neon flying squid
19 surface-mid water squid
20 deep water squid
21 Mackerel
22 Pacific pomfret
23 Sardine
24 Anchovy
25 Pacific saury
26 Phytoplankton
27 Euphausiids
28 Copepods eaten by whales
29 Other Copepods
30 Detritus

0.0002

Fishery2(t/km /year)

0
0
0.035
0.001
0.016
0.00020.0003
0
0.007
0.076
0
0.083
0
0.018
0.137
0.151
0
0
0
0
0

6

Tale 2. Criteria for the level of uncertainty used in the in-put parameters.
Biomass
OptionEstimated by Ecopath
From other model
Guesstimate

Index value000Conf. int.(+/- %) Pattern
80
80
80

Consumer: Approximate or indirect method
Producer: Indirect method (remote sensing)

0.4

50

Consumer: Sampling based, low precision
Producer: Locally based, low precision

0.7

30

Consumer: Sampling based, high precision
Producer: Locally based, high precision

1

10

P/B and Q/B
OptionEstimated by Ecopath
Guesstimate
From other model
Empirical relationshipIndex value
0
0.1
0.2
0.5

Conf. int.(+/- %) Pattern
80
70
60
50

Consumer: Similar group/species, similar system
Producer: Similar system, low precision

0.6

40

Similar group/species, same system
Producer: Same system, low precision

0.7

30

Consumer: Same group/species, similar system
Producer: Similar system, high precision

0.8

20

Consumer: Same group/species, same system
Producer: Same system, high precision

1

10

Diet
OptionGeneral knowledge of related group/species
From other model
General knowledge for same group/species
Qualitative diet composition study
Quantitative but limited diet composition study
Quantitative, detailed, diet composition study

Index value
0
0
0.2
0.5
0.7
1

Conf. int.(+/- %) Pattern
80
80
60
50
30
10

Catch
OptionGuesstimate
From other model
FAO statistics
National statistics
Local study, low precision/incomplete
Local study, high precision/complete

Index value
0.1
0.1
0.2
0.5
0.7
1

Conf. int.(+/- %) Pattern
70
70
60
50
30
10

7

Table 3．Parameters of the mass-balanced Ecopath model (the values indicated in grey are estimated by the model).

8

Table 4. Relative biomass of minke whales and pacific saury for the coming 10, 20, 30, 40 and 50 years, when minke whales are not harvested for the coming 50 years. V is thevulnerability parameter in Ecosim which controls the trophic impact of the ecosystem. Description on different functional response curve is detailed in the text.

Scenario: Minke whale catch is 0 for the coming 50 yrsv
Functional response / Species
Type I
2Type II(mixed trophic
Type III
impact)Type III + otherType I
20Type II(top-down) Type III
Type III + otherType I
prop. to TL Type II( v max =20) Type III
Type III + otherType I
prop. to TL Type II( v max =10000) Type III
Type III + other(B current+40 )/ B current( B current+20 )/ B current( B current+30 )/ B current( B current+50 )/ B current( B current+10 )/ B current
minke whale pacific saury minke whale pacific saury minke whale pacific saury minke whale pacific saury minke whale pacific saury
1.09
1.00
1.15
1.00
1.19
1.00
1.22
1.00
1.24
1.00
1.13
1.00
1.23
0.99
1.30
0.9 9
1.35
0.99
1.38
0.99
1.11
1.00
1.23
1.00
1.34
1.00
1.45
1.00
1.54
1.00
1.14
1.00
1.20
1.00
1.21
1.00
1.22
1.00
1.22
1.00
1.11
1.00
1.22
0.98
1.33
0.97
1.43
0.96
1.53
0.96
1.18
0.98
1.37
0.96
1.58
0.9 3
1.81
0.91
2.03
0.89
1.12
1.00
1.26
0.99
1.41
0.98
1.58
0.97
1.76
0.97
1.22
0.99
1.46
0.98
1.72
0.96
1.99
0.95
2.24
0.95
1.10
0.99
1.21
0.98
1.31
0.97
1.40
0.95
1.48
0.94
1.17
0.98
1.36
0.95
1.55
0.9 3
1.74
0.90
1.92
0.87
1.12
0.99
1.26
0.97
1.41
0.95
1.57
0.92
1.74
0.89
1.21
0.98
1.44
0.95
1.65
0.91
1.83
0.88
1.96
0.85
1.11
0.99
1.22
0.97
1.33
0.94
1.44
0.90
1.53
0.87
1.18
0.97
1.38
0.92
1.60
0.8 5
1.82
0.78
2.03
0.71
1.12
0.99
1.26
0.95
1.41
0.90
1.58
0.84
1.75
0.78
1.22
0.97
1.48
0.91
1.73
0.83
1.97
0.73
2.13
0.64

Type II

Type I

prey availability
prey availability
9

consumption rate

predator per capita

consumption rate

predator per capita

consumption rate

predator per capita

Type III

prey availability

Figure 1．Food-web assumed in the model and the trophic level estimated for each species.

11Figure 2. An example of output showing that effect of the short-term increase in the vertical axis species on the horizontal axis species obtained by Ecopath. Upward bars represent
positive impact, and downward bars represent negative impact.
12