No 32 | 2019

POLICY BRIEF

Implications of climate-driven redistribution of tuna for
Pacific Island economies
PurposeThe aims of this policy brief are to:• summarise the latest projected effects of climate change
on tuna caught by purse-seine in the exclusive economic
zones (EEZs) of Pacific Island countries and territories(PICTs); and• raise awareness of the implications of climate-driven
movement of tuna for government revenues earned by
PICTs from industrial tuna fishing, and for other socioeconomic benefits derived from tuna.

Key messages
The projected eastward redistribution of skipjack and yellowfin tuna due to climate change is expected to reduce the total tuna
catch within the combined EEZs of the 10 PICTs where most purse-seine occurs by approximately 10% by 2050. The projected
decreases in purse-seine catches are likely to reduce the contributions that tuna fishing licence fees make to the government
revenues of many of these PICTs. Identifying how to maintain the benefits from tuna in the face of the impacts of climatechange is essential for Pacific Island economies.

Economic importance of tuna fishing
The economic development of PICTs depends heavily on
the tuna resources of the western and central Pacific Ocean(WCPO) and on purse-seine fishing. The WCPO tuna catchaveraged 2.7 million tonnes per year between 2014 and2018, with harvests from the EEZs of PICTs representing 58%
of this catch.

Purse-seine fishing produces an average of 70% of the WCPO
tuna catch. The purse-seine catch is dominated by skipjack
tuna (76%), with yellowfin and bigeye tuna comprising 20%
and 4%, respectively.

Purse seiner transshipping its catch, Federated States of Micronesia – ©Francisco BlahaHAWAII

Licence fees
= $6.8 m
8.7% Gov’t
revenuePALAU

NORTHERNMARIANAISLANDSGUAMFEDERATED STATESOF MICRONESIAPAPUA NEW GUINEA

Licence fees
= $63.2 m
56.0% Gov’t
revenue

MARSHALL ISLANDS

Licence fees
= $128.8 m
4.9% Gov’t
revenue

Licence fees
= $29.2 m
60.0% Gov’t
revenue

Parties to the Nauru Agreement

Licence fees
= $27.8 m
28.0% Gov’t
revenue
NAURU

SOLOMON
ISLANDS

Licence fees
= $23.4 m
62.0% Gov’t
KIRIBATI
revenue

KIRIBATI

Licence fees= $41.6 m
9.8% Gov’t
revenue

TUVALU

Licence fees
= $13.3 m
98.0% Gov’t
revenue

TOKELAUWALLIS SAMOA& FUTUNAFIJI
NEW CALEDONIA

Licence fees
= $118.3 m
66.0% Gov’t
revenue

COOK ISLANDSKIRIBATI

Licence fees
= $12.8 m
11.0% Gov’t
revenue

AMERICANSAMOAVANUATUNIUE

FRENCH POLYNESIATONGAAUSTRALIA

Figure 1. The economic benefits of tuna fishing for Pacific Island countries and territories (2016).
Licence fees from tuna fishing make extraordinary contributions
to the government revenues of many PICTs. Purse-seine
fishing provides the vast majority of these important national
economic benefits.
Six PICTs derive approximately 30–100% of their government
revenues from tuna fishing licence fees (Figure 1).
Table 1. Projected changes (%) in biomass of skipjack (SKJ), yellowfin (YFT)
and bigeye (BET) tuna by 2050 under a high emissions scenario in the exclusive
economic zones (EEZs) of the 10 Pacific Island countries and territories wheremost purse-seine fishing occurs, and in the high-seas areas shown in Figure 3.
Area
EEZs west of 170°E FSMMarshall Islands
Nauru
Palau
Papua New Guinea
Solomon Islands
EEZs east of 170°E Cook Islands
Kiribati
Tokelau
TuvaluI1IW WCPFC
I2I3I4I5I6I7I8I9H4H5EPO-N
IW EPO
EPO-C
EPO-S

SKJ

YFT

BET-29-17-8-28-43-171618-14-12-52-15
21
565
101326
88-10382980
47-19-12-16-12-21-928
7
143-19-12-71
23
1220
335
415
4355
71

3-3-44-4-231-1-20-33-42
36-12-1
1
12920

Tuna fishing also makes significant contributions to the grossdomestic product of Federated States of Micronesia andMarshall Islands. It also supports the employment of almost
25,000 people across the region, through jobs on fishingvessels, in fish processing operations, and in management oftuna fisheries.
By 2035, 25% of all fish required for food security of PacificIsland people will need to be supplied by tuna. To meet thisneed, more than 85,000 tonnes of tuna and tuna-like species
will be required annually for domestic consumption within thenext 15 years.
The tuna stocks that provide these economic and social
benefits are in a healthy condition (i.e., none of the tropicaltuna species are overfished and overfishing is not occurring),
due largely to strong management of purse-seine fishing in theEEZs of PICTs, particularly in the waters of the Parties to theNauru Agreement (PNA).
The Regional Roadmap for Sustainable Pacific Fisheries,endorsed by Pacific Islands Forum Leaders in 2015, recognises
the deep dependence of PICTs on tuna, and outlines plans tomaximise the sustainable economic and social benefits derived
from this valuable natural resource. However, a key questionis, ‘Will climate change disrupt the goals of the Roadmap?’

Projected changes in distribution of tuna
The most recent modelling of projected changes to the biomassof tuna in the EEZs of PICTs, and high-seas areas (Figure 2),
indicates that continued high greenhouse gas (GHG) emissions
are very likely to alter the distribution of skipjack and yellowfin
tuna. Both species are expected to shift progressively to theeast, and to subtropical areas, by 2050 (Figure 2). In contrast,
the redistribution of bigeye tuna due to climate change isexpected to be modest (Table 1).

Skipjack

2005

2050

Yellowfin

40° N

40° N

20° N

20° N

0°

0°

20° S

20° S

40° S

40° S

40° N

40° N

20° N

20° N

0°

0°

20° S

20° S

40° S

40° S
150°E

160°W

0110°W

0.1

0.2

150°E

0.3

0160°W

110°W

0.05

Tonnes per km2

0.1

0.15

Tonnes per km2

Figure 2. Projected distributions of skipjack and yellowfin tuna biomass in the Pacific Ocean in 2005, and in 2050 under a highgreenhouse gas emissions scenario.
In general, climate-driven movements of skipjack and yellowfin
tuna are expected to decrease the biomass of both species inthe EEZs of PICTs west of 170°E, and to increase their biomassin the EEZs of PICTs east of 170°E and in subtropical waters(Table 1).

The biomass of skipjack and yellowfin tuna is also projected
to increase in most high-seas areas because these areas occur
mainly east of 170°E or in subtropical regions. The equatorial
high-seas pockets (I1, I2, I3 and H4 in Figure 3) are theexception – the biomass of skipjack and/or yellowfin tuna is
projected to decrease in those areas (Table 1).

– 60° N

– 40° NI6– 20° N

– 0°

I6

I3

I6I1

Western and centralPacific Ocean

I6I3

I3

I8

I7

– 40° S

I4
H4I2

– 20° S

I6

I7Eastern
Pacific Ocean
EPO-N

I5
H5

I9

I5

I5

I7

EPO-C

I7

EPO-S

– 80° W

– 100° W– 120° W– 140° W– 180°– 160° E– 140° E– 120° E– 160° W

WCPFC Convention area

– 60° S

Figure 3. High-seas areas in the western and Central Pacific Ocean and eastern Pacific Ocean used to estimate changes in biomass of tuna.

Implications for Pacific Island economies

Policy considerations

Based on the assumption that there is a direct relationshipbetween the amount of tuna caught within an EEZ and thefishing licence fees paid to a PICT, the progressive eastward
movement of tuna is expected to reduce total government
revenue in the majority of the 10 PICTs where most purseseine fishing occurs.

The projected loss of government revenue by tuna-dependent
Pacific Island economies, which produce a trivial percentageof global GHG emissions, positions PICTs to negotiate to retain
the important socio-economic benefits they receive from tuna,
regardless of climate-driven redistribution of tuna resources.

By 2050, under a high GHG emissions scenario, movement ofa greater proportion of the tuna caught by purse-seine into
high-seas areas (where industrial fishing fleets do not have to
pay for fishing access) could reduce total government revenue
in many PICTs by up to 15% (Table 2).
Climate-driven redistribution of tuna could reduce thecombined annual fishing licence revenues received by the 10
PICTs by more than USD 60 million at today’s values (Table 2).
However, the estimated percentage changes in total
government revenues for each PICT (Table 2) need to betreated with caution. At present, these estimates do notaccount for i) management responses; ii) effects of changes
in tuna biomass on catch and effort, and therefore the valueof access to particular EEZs; and iii) the impact of tunaredistribution on the degree of control that PICTs exert overfisheries targeting tuna. For example, movement of more tunafrom the EEZs of PNA countries into high-seas areas would beexpected to reduce the effectiveness of the PNA Vessel Day
Scheme to some extent.
Table 2. Tuna licence fees earned by 10 Pacific Island countries and territories (PICTs) in
2016, and projected changes in licence fees and total government revenue by 2050 due
to redistribution of tuna. Projected changes in tuna biomass are averages for skipjack,yellowfin and bigeye tuna (Table 1), weighted by 76%, 20% and 4%, respectively.
ChangeTuna(%) in
licencecombinedrevenue biomass of2016 (USD SKJ, YFT &million) BET tuna by2050PICTTunalicencerevenue
2050(USDmillion)

Change from 2016
to 2050
TunaTotal
licencegov’t
revenuerevenue(USD(%)
million)West of 170°E
PNG

128.8

-37

81.1

-47.7

-1.8

FSM

63.2

-26

46.8

-16.4

-14.6

Palau

6.8

-24

5.2

-1.6

-2.1

Marshall Islands

29.2

-15

24.8

-4.4

-9.0

Solomon Islands

41.6

-15

35.4

-6.2

-1.5

Nauru

27.8

-9

25.3

-2.5

-2.5

23.4

-9

21.3

-2.1

-5.6

To strengthen such negotiations, the uncertainty associatedwith the modelling and preliminary economic analysesdescribed above needs to be reduced. Some of this uncertainty
arises because the climate modelling assumes that skipjack,yellowfin and bigeye tuna resources in the Pacific Ocean areeach comprised of a single mixed stock. Preliminary genetic
research indicates that this is unlikely to be the case.
To reduce uncertainty and enable PICTs to assess climate-driven
losses in government revenues and related economic benefits
from tuna fishing with confidence, investments are needed to:• identify the structure of Pacific tuna stocks; i.e., thenumber of self-replenishing populations (‘stocks’) within
the range of each tuna species;• model the response of each stock under both high- andlow-GHG emissions scenarios; and• compile integrated maps of the expected redistributionof each tuna species within its range under different GHG
emissions scenarios.
These investments will enable PICTs to identify future changes
in tuna revenue with greater certainty, and to negotiatearrangements to retain the present benefits they receive fromtuna, regardless of the impacts of ocean warming on the tuna
resources currently within their EEZs.

Further reading
Brouwer S et al. (2018) The Western and Central Pacifictuna fishery: 2017 overview and status of stocks. Oceanic
Fisheries Programme, Tuna Fisheries Assessment Report
No. 18. Pacific Community, Noumea.
Senina I et al. (2018) Impact of climate change on tropical
Pacific tuna and their fisheries in Pacific Islands waters andhigh seas areas. WCPFC-SC14-2018/EB-WP-01. Westernand Central Pacific Fisheries Commission, Pohnpei.

For more information or technical assistance,
contact SPC’s Oceanic Fisheries Programme (ofpinfo@spc.int)

East of 170°E
TuvaluTokelau

13.3-8

12.2

-1.1

-7.8

Kiribati

118.3

15136.0+17.7+9.9

Cook Islands

12.81815.1+2.3

+2.0

Total

465.2

403.2

62.0

Pacific Community Headquarters
95 Promenade Roger Laroque, BP D598848 Noumea, New Caledonia
Phone:+687 26 20 00 | Fax:+687 26 38 18
spc@spc.int | www.spc.int

Acknowledgements – Developed in collaboration with Conservation International, Collecte Localisation Satellite,
the Pacific Islands Forum Fisheries Agency and the Australian National Centre for Ocean Resources and Security.