Building climate resilience, social sustainability and equity in global fisheries

The paper addresses the lack of operational tools to help achieve the Paris Agreement (PA) climate targets within the global fisheries sector. Climate change is diminishing marine biodiversity and associated ecosystem services such as food provision. While Article 6 of the PA enables international cooperation via carbon market mechanisms, fisheries research has focused mainly on emissions reductions from fuel use and on ocean carbon fluxes impacted by fishing. Here, the authors focus on the fish carbon mechanism (blue carbon) whereby marine vertebrates store atmospheric carbon as biomass and transport it to deep waters and sediments. The study proposes a Market-Based Solution (MBS) that internalizes the opportunity cost of fishing in terms of forgone blue carbon sequestration. By creating a scarcity value for the right to fish via carbon sequestration allowances based on historical landings (initial allowances), the scheme builds a supply curve of willingness to reduce fishing derived from shadow prices when fisheries enter a CO₂ trading mechanism. A key concept is the fish withdrawal price at which fleets are indifferent between fishing (selling fish) and trading their blue carbon allowances; if first-sale prices are below the withdrawal price, fleets would trade allowances instead of fishing. The study uses the EU Emissions Trading System as a reference and also evaluates scenarios using the Social Cost of Carbon (SC-CO₂) for 2025, 2030, and 2050. Beyond efficiency, the study examines distributional and equity effects, testing whether the MBS reallocates fishing effort away from biologically negative, economically inefficient, and socially inequitable activities, potentially improving climate resilience and social sustainability globally.

Data: Reconstructed catch and ex-vessel price data (2010 US$) for 2011–2018 were obtained from the Sea Around Us (SAU) dataset, disaggregated by FAO major fishing areas, Exclusive Economic Zones (EEZs), high seas, fishing countries, fleet (artisanal or industrial), gear, and taxonomic level (species/genus/family). Discards, recreational, and subsistence catches were excluded.

Blue carbon content: Species-specific carbon content was sourced from the literature. For taxa lacking specific values, the mean carbon content at the lowest available taxonomic level (genus/family) was used.

Withdrawal price and trading rule: For each data entry (species S; FAO area A; EEZ; year Y; fishing sector FS; gear FG), a withdrawal price was computed as the fish market value per unit of embodied CO₂e: Withdrawal price = (Market price at A, EEZ, Y) / (Landings of S at A, EEZ, Y divided by carbon content of S) multiplied by a sector factor. The factor equals 1 for artisanal fleets (assuming value added equals landing value) and 0.14 for industrial fleets, reflecting only normal profits (owner of capital remuneration) based on the EU fleet’s net profit-to-landing value ratio. A comparison algorithm implemented in R marked positive landing removals (i.e., additional sequestration) where the withdrawal price was below a given CO₂e price, indicating it is more valuable to trade allowances than to fish.

Carbon price scenarios: The analysis used a 2022 EU ETS reference price of US$66 per tCO₂e and SC-CO₂ values of US$165 (2025), US$203 (2030), and US$543 (2050), representing the monetized damages per tonne of CO₂ consistent with limiting warming to 2.5 °C on average over 100 years.

Inequality analysis: The Lorenz curve and Gini coefficient were computed for income from landings under the status quo and under the MBS (landings income plus CO₂e trading income), using country population data from the United Nations to assess distributional impacts.

Price effects: The change in average global ex-vessel price was calculated by comparing (a) total landing value over 2011–2018 divided by average landings with (b) total landing value plus MBS value under each carbon price divided by average landings.

Sensitivity analyses: Initial allowances (the cap) were set to average landings (2011–2018), with standard errors reported (0.106 ± 0.0083 Gt yr⁻¹; value US$222 ± 0.0143 billion yr⁻¹). Resulting sequestration under ETS 2022 and SC-CO₂ 2050 included uncertainty (0.027 ± 0.0007 Gt yr⁻¹ and 0.122 ± 0.0023 Gt yr⁻¹, respectively). Alternative industrial factors of 0.33 (general economy capital share) and 1 were tested, showing that higher factors reduce landings removals and sequestration, especially at lower carbon prices, with convergence at 2050 SC-CO₂. Treating artisanal fleets like industrial (factor 0.14) raised sequestration at 2022 ETS from 0.027 to 0.034 Gt yr⁻¹ (+29%) and had negligible effect at 2050 SC-CO₂ (0.122 to ~0.122 Gt yr⁻¹), with additional sequestration entirely from artisanal reductions.

• Baseline activity: Mean reported landings (industrial + artisanal) in EEZs and high seas averaged 0.106 Gt yr⁻¹ (US$222 billion yr⁻¹) in 2011–2018. Top species: anchoveta 11%, unidentified marine fishes 10%, Alaska pollock 4% of landings. Artisanal fleets accounted for about 25% of landings; high seas 3%.
• Blue carbon cap: Total landings embody 0.161 Gt CO₂e yr⁻¹ as initial allowances, valued between ~US$11 billion yr⁻¹ at 2022 ETS prices and ~US$88 billion yr⁻¹ at 2050 SC-CO₂.
• Global sequestration potential under MBS: 0.027 Gt CO₂e yr⁻¹ (17% of cap) at US$66/t (2022 ETS); up to 0.122 Gt CO₂e yr⁻¹ (76% of cap) at US$543/t (2050 SC-CO₂), yielding ~US$66 billion yr⁻¹ in potential benefits. If CO₂ prices reach the 2050 SC-CO₂, ~75% of global landings would be more valuable as carbon than as food.
• Regional and national contributions: Peru and China are largest contributors to landings and CO₂e removals (Peru ~12–13%, China ~9% each). At 2022 prices, Pacific Northeast could see 52% of landings more valuable as carbon; by 2050 SC-CO₂, Atlantic Northeast could reach 92%.
• Distributional and equity impacts: Gini coefficient decreases from 0.560 (status quo) to 0.559 (2022 ETS) and to 0.528 (2050 SC-CO₂), indicating more equal distribution of ocean income. The top 20% of the world population’s share of fishery income falls from 60% to 48% by 2050. Regions gaining most by 2050: Northern Africa and Western Asia (+44% income), Central and Southern Asia (+36%), Sub-Saharan Africa (+33%). Beneficiary EEZs include Cape Verde, Guadeloupe (France), Faroe Islands and Greenland (Denmark), and Madeira (Portugal); no change for Turks and Caicos (UK), Bahamas, Antigua and Barbuda, North Cyprus. Finland could sequester 80%, 95%, 99%, and 99% of its allowances at 2022, 2025, 2030, and 2050 prices, respectively.
• Opportunity costs and prices: Not adopting the scheme implies forgone benefits of ~US$0.8 billion yr⁻¹ (2022), US$6.7 billion yr⁻¹ (2025), US$10 billion yr⁻¹ (2030), and US$49 billion yr⁻¹ (2050), equivalent to 0.3%, 3%, 4.5%, and 22% of landings value, respectively. Average ex-vessel prices would rise by ~0.3% to US$2109/t in 2022 and by ~22% to US$2567/t by 2050 (holding status quo quantities).
• Fleet segments and gears: At 2022 prices, additional sequestration derives 1.7% from artisanal and the rest from industrial removals; 1.1% of artisanal vs 21% of industrial allowances additionally sequestered. At 2050 SC-CO₂, these rise to 26% (artisanal) and 92% (industrial). High seas removals: 5% at 2022; 20% (18% CO₂e) in 2025; 21% (20% CO₂e) in 2030; 60% (59% CO₂e) in 2050. Most-affected gears at 2022 prices: pelagic trawlers (−50% of status quo landings), hand lines (−41%), encircling nets (−24%), purse seiners (−21%), harpoons (−19%); by 2050 SC-CO₂, removals approach ~90% for these gears.

The MBS internalizes the climate regulation service of harvested fish via blue carbon content, enabling fleets to choose between fishing and trading carbon allowances based on withdrawal prices. The results indicate substantial potential to sequester carbon (up to 76% of the blue carbon cap) while reallocating effort away from biologically harmful and economically inefficient activities. The approach can reduce overfishing pressure, increase climate resilience, and improve equity by shifting income distribution toward lower-income regions and countries. Estimated increases in average ex-vessel prices reflect the socialized climate costs of fishing, aligning incentives with climate targets. Reported sequestration is a lower bound since it excludes other mechanisms (e.g., biological pump, sediment carbon disturbance by certain gears). The scheme complements existing fisheries management (e.g., MPAs) and broader paradigms like degrowth economics. Although dynamic stock effects were not modeled, reduced landings could bolster stock resilience and broader ecosystem services. The scale of benefits depends on carbon prices; if prices approach SC-CO₂ consistent with stringent climate goals, the scheme yields strong climate and social outcomes.

This study operationalizes a market-based solution to incorporate global fisheries into carbon trading by assigning blue carbon-based initial allowances and enabling fleets to trade sequestration rights. Applying the mechanism globally suggests sequestration up to 0.122 Gt CO₂e yr⁻¹, with potential annual benefits of around US$66 billion at 2050 SC-CO₂, and reallocates fishing effort away from activities with negative biological, economic, and social balances. The scheme enhances climate resilience and improves equity in the distribution of ocean-derived income. Future work should refine SC-CO₂ inputs as new projections and damage estimates evolve, extend accounting beyond fish blue carbon to include additional ocean carbon pathways (e.g., biological pump, sediment disturbance), explore implementation pathways to address free-riding and jurisdictional valuation differences, and assess coupled ecological-economic dynamics under reduced fishing effort.

• Sequestration estimates are conservative, considering only fish blue carbon and excluding other ocean carbon pathways (e.g., biological pump) and seabed carbon disturbances by gears.
• The fishing sector is not currently part of any global carbon trading system; implementing a compulsory, globally coordinated scheme faces free-riding risks and governance challenges.
• National managers may assign differing values to sequestered carbon despite the global nature of climate benefits, complicating harmonization.
• Uncertainty in future carbon prices reaching SC-CO₂ and ongoing revisions to SC-CO₂ estimates affect projected benefits.
• Economic parameters (e.g., industrial sector factor 0.14) are based on EU fleet data and may not generalize globally; sensitivity analyses indicate material impacts on outcomes.
• Dynamic ecological feedbacks (stock rebuilding, productivity changes) are not modeled and could alter long-run outcomes.