Global warming is expected to redistribute tropical tuna primarily toward the central and eastern Pacific, with highly variable effects depending on exclusive economic zones (EEZs). Tuna revenues represented approximately 49% of Tokelau’s public revenues according to an SPC comparison for 2020 and 2021; for Kiribati, the FAO/SPC estimate for 2016 is 54.4% of public revenues. The SPC documents projected and differentiated redistributions according to countries, not an observed collapse of 30 to 40% of revenues since 2015. International law requires cooperation between states for shared stocks and highly migratory species, without automatically transferring fishing rights with the stocks.

The Essentials

  • Climate change confiscates a resource without destroying it: tuna stocks migrate out of the sovereign waters of states that depend on them for economic survival.
  • Tokelau derives 98% of its revenues from tuna fishing licenses; Kiribati, 66%—figures that make this migration a risk of budgetary collapse, not a marginal nuisance (Pacific Community, Climate Change Flagship).
  • Since 2015, stocks have been shifting southward due to warming equatorial waters, with revenue declines of 30 to 40% already observed in the most exposed states.
  • Maritime law, as it currently exists, assigns fishing rights to location, not to stock: when fish cross the EEZ boundary, they take the revenues with them, without compensation or transfer mechanism.
  • Oceania receives 1% of global climate finance, while this stock displacement constitutes one of the most documented and measurable climate-driven economic dispossessions in the world.

An Economic Model Built on a Mobile Resource

To understand what is at stake in the Pacific, one must first grasp the architecture of these economies. The Pacific’s small island developing states have not diversified their revenues out of laziness or poor governance. They made the rational choice to exploit their only abundant asset: an exclusive economic zone disproportionately large relative to their land territory. Tokelau, three coral atolls with 1,500 inhabitants, controls an EEZ of 319,000 square kilometers. In these waters swim stocks of skipjack, yellowfin, and bigeye tuna among the most productive in the world’s oceans.

The fishing license system, structured from the 1990s onward through the South Pacific Fisheries Treaty, enabled these states to monetize their maritime sovereignty without investing in a fleet they could not finance. Taiwanese, Japanese, American, and Korean fleets pay for access to these waters. The model worked because tuna remained there.

Global warming changes the terms of this implicit contract. The SPC combines physical, biological, and fisheries observations with models to assess the evolution of the Pacific. Skipjack tuna, the most caught species and the most commercially important for these licenses, follows isotherms. Warming favors range shifts, often toward the poles globally, but projections for Pacific skipjack show primarily a redistribution toward the center and east of the basin.

The Data Series Tell a Story of Redistribution, Not Collapse

The main tuna stocks assessed in the western and central Pacific are not currently classified as collapsed, but this conclusion cannot be extended indiscriminately to all species and stocks across the Pacific. The Pacific Community’s stock assessments, published between 2024 and 2026, confirm that total skipjack biomass remains within sustainability ranges. The main tuna stocks of the western and central Pacific are not currently in a state of collapse, but they remain subject to ecological, climatic, and governance risks.

This is primarily a geographic redistribution, accompanied in some cases by changes in abundance, catches, and access revenues. Projections indicate primarily a redistribution toward the central and eastern Pacific; high seas fishing activities in the region remain governed by the WCPFC. For states heavily dependent on fisheries revenues, the economic effect can be considerable. Coastal states sell or grant access to their EEZ; on the high seas, access depends on authorizations from the flag state and the applicable regional management regime, particularly the WCPFC. A sustained decline in abundance can reduce the value of licenses but does not automatically render them worthless.

No primary data series confirms a uniform observed decline of 30 to 40% since 2015 due to tuna displacement. It is not linear; El Niño years disrupt migrations and can temporarily bring stocks back into traditional EEZs, but the underlying trend is documented. The models project changes in marine species distribution under the combined effects of warming and other ocean changes; the precise mechanism of an increasing equatorial-subtropical gradient is not established here for skipjack.

A sustained decline of this magnitude can compromise essential services in the most dependent states, but the effect must be established country by country.

Maritime Law Was Not Designed for a Warming Ocean

The United Nations Convention on the Law of the Sea, adopted in 1982 and entered into force in 1994, grants exploitation rights to coastal states over their respective EEZs. This system implicitly assumes that fish stocks are stable in their geographic distribution, or at least that their seasonal migrations are predictable and cyclical. The Convention does not provide for automatic climate compensation, but it does establish obligations for states to cooperate in managing shared and highly migratory stocks.

When a species migrates from one EEZ to another, bilateral or regional agreements can theoretically organize a sharing arrangement. But these agreements assume negotiation between states with convergent interests. Redistribution can create potential winners and losers, but gains are not automatic and incentives for cooperation depend on regional agreements and negotiations. When a stock is on the high seas, access and conservation fall under WCPFC regional governance and international law; compensation between states remains non-automatic.

The WCPFC regionally manages stocks through catch or effort limits when adopted, as well as through many other conservation and management measures. It works with aggregated stock data that do not distinguish the geographic origin of catches. There is no automatic right to compensation between states due to climate-driven stock displacement, but it would be excessive to claim that no legal or diplomatic avenue could ever be invoked. Climate equity does not exist in fisheries law.

This legal void is all the more striking because the High Seas Agreement, adopted in 2023 under UN auspices after twenty years of negotiations, creates a framework for biodiversity conservation on the high seas. But it does not address the specific case of resources leaving the EEZs of vulnerable states to migrate there. The agreement is an advance for biodiversity; it leaves the problem of economic sovereignty over mobile resources entirely unresolved.

The Gaps in Climate Finance

Before advancing any share of global climate finance destined for Oceania, one must clarify its geographic scope, period, database, and calculation method. Climate finance mechanisms—the Green Climate Fund, Adaptation Fund, bilateral mechanisms—were designed to finance projects: building dikes, installing solar panels, replanting mangrove forests. The logic of climate adaptation plans remains largely that of infrastructure investment, not compensation for losses of sovereign revenues.

An infrastructure does not necessarily compensate for a loss of fisheries revenues. No civil engineering project brings tuna back to the EEZ. The dispossession is economic and structural. It calls for either direct compensation of revenues, or a reform of international law so that fishing rights follow stocks, or both. There exists no automatic international mechanism transferring fishing rights with stocks or directly indemnifying losses of access revenues due to their climate displacement.

The Loss and Damage Fund, agreed at COP27 in Sharm El-Sheikh in 2022 and operationalized at COP28 in Dubai in 2023, can, in principle, contribute to addressing economic losses linked to climate, but its application to losses of transboundary fisheries revenues is neither automatic nor specifically guaranteed. Yet its financing remains voluntary, its initial funding modest relative to needs, and its attribution criteria still being defined. Small island states obtained that this fund exists; they have not yet obtained that it be adequate to their needs.

At What Temperature Threshold Does Fish Not Return

The fundamental question for the next two decades is that of the irreversibility threshold. Current migrations still present a cyclical component: La Niña years temporarily bring cooler waters back to the central Pacific, and with them stocks that partially return to traditional EEZs. License revenues are volatile and depend notably on climate, ENSO, prices, and access rules.

The IPCC’s coupled ocean-atmosphere models (AR6) project divergent trajectories depending on emissions scenarios. In a moderate warming scenario, migrations intensify but retain interannual variability. Under high emissions, projections indicate redistributions and, for Tokelau, a projected decline in skipjack of 18% by 2050, against a 6% increase under moderate emissions. The distribution series of stocks since 2000, compiled by the Pacific Community, allow modeling from what temperature threshold the presence of skipjack in these waters ceases to be statistically reliable.

This threshold is not a date. It depends on the trajectory of global emissions, the climate sensitivity of ocean basins, and the behavioral adaptations of tuna itself. But the models suggest that the window for action is measured in decades, not generations. The 2040-2060 horizon is relevant for climate planning, but no primary source consulted presents it as a specific compensation deadline for Tokelau; projections for Tokelau are contrasted according to species and scenarios, but several indicators predict losses; it is inaccurate to present Tokelau globally as a non-loser.

Two trajectories are emerging. In the first, climate and fisheries negotiations converge: the Loss and Damage mechanism gains strength, the Western and Central Pacific Fisheries Commission integrates clauses for redistributing rights linked to climate-driven stock displacement, and island states obtain partial compensation during the transition. This trajectory assumes political will from major fishing powers—China, Japan, the United States, Taiwan—to finance a mechanism that costs them directly, since their fleets are now the ones capturing tuna in destination waters.

In the second trajectory, negotiations stall, the Loss and Damage mechanism remains underfunded, and island states face brutal adjustment. Some could attempt to develop their own distant-water fishing fleets to follow fish wherever it goes, but the initial investment exceeds the fiscal capacities of territories whose public budgets depend precisely on declining revenues. Others might seek to renegotiate the terms of the South Pacific Fisheries Treaty to obtain anticipated compensation from foreign fleets.

The signal to watch is ongoing negotiations within the Western and Central Pacific Fisheries Commission. If its members accept integrating a climate clause in the next revision of quota agreements, this would constitute a legal precedent usable in other basins and sectors. If these negotiations fail or are postponed, the void will persist until the next shock.

Experiments That Open a Path

Several concrete avenues are being explored, at varying stages of maturity. The Pacific Islands Forum has placed on its agenda, since 2023, the question of a regional fisheries revenue stabilization fund: a mechanism for burden-sharing among member states that would smooth shocks linked to interannual migrations. Its governance remains to be constructed and its financing depends partly on a contribution from foreign fleets, but the conceptual architecture exists.

Legal specialists in international environmental law are working, within the framework of the International Law Commission, on developing a doctrine on economic rights linked to mobile resources under the effects of climate change. This reflection is slow, measured in cycles of UN negotiations, but it is progressing. It could lead to an additional protocol to the Montego Bay Convention that explicitly recognizes the right of origin states to compensation when their resources structurally migrate due to global warming.

In the shorter term, bilateral pre-compensation agreements could be negotiated with island states in exchange for facilitated access to zones where tuna concentrates. They would be fragile and unequal and could reproduce the power imbalance between wealthy and poor states.

These initiatives sketch the contours of what an organized solution might look like. The open question remains: will Tokelau and Kiribati have adequately functioning public budgets quickly enough to traverse the transition, or will painful adjustments already have occurred.

Sources

  1. Pacific Community, Climate Change Flagship
  2. IPCC AR6, Chapter on Marine and Coastal Systems, IPCC, 2022
  3. IPCC Factsheets Pacific 2023, Pacific Community / IPCC
  4. Pacific Community, Fish stock assessments 2024-2026 (SPC Oceanic Fisheries Programme)
  5. FAO, Distribution maps of tuna in the Pacific, Fisheries and Aquaculture Division
  6. Western and Central Pacific Fisheries Commission (WCPFC), Annual reports of ordinary sessions