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Sixteen of the 23 major tuna stocks assessed achieve a passing score under Principle 1 of the MSC Fisheries Standard. However, only nine have fully implemented, well-defined rules for reducing catches when stock abundance begins to fall. Many stocks are therefore in good biological condition today, but their management safeguards are not yet complete.

Stocks are stronger, but management is not moving at the same pace

The latest report from the International Seafood Sustainability Foundation examines 23 major tropical and temperate tuna stocks across the Atlantic, Mediterranean, Indian and Pacific Oceans, as well as waters in the Southern Hemisphere.

The assessment does more than establish how much fish remains in the sea. Principle 1 considers the biological status of the stock, the effectiveness of the harvest strategy, the rules used to control fishing pressure, the quality of monitoring and the reliability of scientific assessments.

To pass, a stock must achieve an overall score of at least 80, with no individual performance indicator falling below 60. Healthy biomass alone is not enough.

This is what makes the report particularly relevant to the seafood supply chain. A stock may currently be productive and still fail the assessment if it lacks pre-agreed mechanisms for reducing catches before the resource reaches a critical condition.

Harvest control rules are designed precisely for this purpose. They establish in advance how quotas, fishing effort or other measures should change in response to stock trends. Decisions are therefore linked to scientific indicators and agreed thresholds instead of being left entirely to negotiations once a problem has already emerged.

ISSF records progress across all tuna regional fisheries management organisations. Nevertheless, only nine stocks have fully implemented rules of this kind. The challenge for global tuna management is not simply to rebuild depleted stocks, but to prevent healthy ones from becoming depleted again.

The improvements reshaping the global picture

One of the most significant advances concerns Atlantic bigeye tuna. The latest stock assessment indicates better conditions than in the past: biomass is estimated to be above the level associated with maximum sustainable yield, while fishing mortality is below the corresponding threshold.

Lower catches since 2020 have contributed to the recovery. ISSF nevertheless continues to identify weaknesses in the effective control of removals and in quota implementation.

Western Atlantic skipjack has also improved following the adoption in 2025 of a management procedure capable of adjusting decisions to changes in stock status.

In the Indian Ocean, updated data strengthen the assessments of bigeye and yellowfin tuna. South Pacific albacore, meanwhile, benefits from an interim management procedure supported by a harvest control rule tested through simulation.

Eastern Pacific yellowfin also shows a lower risk of overfishing than in the previous assessment. Moving in the opposite direction, the evaluation of Indian Ocean albacore is now slightly more cautious about the condition of the stock.

The report avoids presenting an overly simple picture. Eastern Atlantic and Mediterranean bluefin tuna, for example, passes Principle 1 thanks to a structured strategy, defined harvest control rules and a management system developed following the rebuilding plan. Uncertainty nevertheless remains over biomass estimates and the scale of unreported catches.

Mediterranean albacore presents a different situation and does not pass the assessment. A rebuilding plan is in force and recent catches have remained close to the agreed limit, but incomplete data, uncertainty over stock status and difficulties in verifying the effectiveness of the measures prevent a more favourable score.

Atlantic yellowfin, Eastern Atlantic skipjack, Western Atlantic bluefin, Eastern Pacific bigeye, North Pacific albacore and Pacific bluefin also fail Principle 1 overall.

The reasons are not identical. In some cases, biological conditions remain the main concern. In others, the decisive weaknesses are the absence of adequate control rules or an overall score below the required threshold.

For the seafood supply chain, knowing the stock is no longer enough

The report provides practical guidance for importers, processors, canners, distributors, foodservice businesses and seafood brands: identifying the species and catch area does not, on its own, provide a complete sustainability assessment.

Companies need to know which stock is being exploited, but also which fishing gear and fleet are involved, what control system applies and how effectively the rules are enforced.

Two products derived from the same species and caught in the same broad ocean area can have very different profiles in terms of monitoring quality, selectivity, bycatch, quota compliance and the ability to reconstruct a reliable chain of documentation.

In the Principle 3 assessment reported by ISSF, the five regional organisations examined — ICCAT, IOTC, WCPFC, IATTC and CCSBT — all exceed the required threshold for international governance. The 2026 update recalculated Principle 1, while the comprehensive Principle 3 scores were carried forward from the previous edition.

All five organisations nevertheless share the same weakness: the performance indicator covering compliance and enforcement remains at 70 points.

The problem is therefore not a lack of conventions, scientific committees or decision-making processes. The difficulty lies in turning those decisions into consistent controls across countries, fleets and ports. Regional organisations define the measures, but much of the surveillance, inspection and sanctioning activity remains the responsibility of individual states.

For the supply chain, this gap represents an industrial risk, not merely an environmental one. A management system that fails to act early can lead to sudden quota reductions, unstable supply, higher costs, difficulties in certification processes and greater reputational exposure.

The new assessment adds an important management perspective to Pesceinrete’s earlier analysis of global tuna stock status in 2026. Scientific assessments and management procedures are advancing, but not at the same speed across stocks and oceans.

The report does not certify individual products

The ISSF document is not a list of certified tuna and does not automatically award the MSC label to a species, stock or product.

It is a comparative benchmark assessment covering Principle 1 and the international components of Principle 3. It does not include Principle 2, which addresses the ecosystem effects of a specific fishing operation, nor does it provide a complete assessment of national management or individual fleets.

Key factors therefore remain outside its scope, including habitat impacts, interactions with sharks, turtles and other vulnerable species, lost fishing gear, ghost fishing and the operational characteristics of the specific fishery.

A healthy stock does not automatically make every fishery exploiting it sustainable.

The ISSF Technical Report 2026-07 therefore presents a broadly positive but far from definitive picture. Most of the assessed stocks achieve a passing score, and several improvements are significant. The real dividing line, however, remains the quality of management.

The overall picture is encouraging, but it is not enough for tuna to be abundant today. Clear rules are needed to reduce catches as soon as the first warning signs appear, without waiting for a stock to enter a crisis.

L’articolo Tuna: 16 of 23 stocks pass MSC Principle 1. Only nine have rules to act if they decline proviene da Pesceinrete.

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