Ifremer Assessment Highlights Slow Progress Towards Sustainable Fishing
A new scientific assessment from Ifremer suggests that around half of the fish landed in mainland France now comes from stocks considered sustainably exploited, although researchers warn progress has slowed and pressure on many populations remains high.
The institute’s 2025 review of fish stock status shows that approximately 50 percent of the volume of fish landed in mainland France in 2024 originated from populations classified as not overfished. The figure represents a modest increase compared with a revised estimate of 44 percent for landings in 2023.
Scientists note that the improvement still leaves the sector far from the objective of having all fish stocks exploited at sustainable levels under the European Union Common Fisheries Policy.
Total fish landings in mainland France reached 306,000 tonnes in 2024, a decline of five percent compared with 323,000 tonnes recorded the previous year. Scientific monitoring currently covers 175 fish populations representing 74 species, each assessed according to reference thresholds linked to fishing pressure and stock biomass.
Clara Ulrich, fisheries scientist and coordinator of fisheries expertise at Ifremer, said the figures show a long-term trend towards improvement, but one that is increasingly slow.
“If we look at the number of populations that are not overfished, the proportion continues to improve slowly. But if we look at the volume of fish landed, we see stagnation around 45 to 50 percent despite reductions in fishing effort and landings. The proportion of populations under pressure also remains high. We are therefore facing overall stabilisation with improvements that are becoming less marked,” Clara Ulrich, researcher and coordinator of fisheries expertise at Ifremer, said.
Herring Reclassification Alters Previous Sustainability Figures
Part of the change in recent figures stems from a scientific revision affecting the status of North Sea and Channel herring.
The stock had previously been classified as being in good condition but has now been reclassified as overfished after scientists lowered the biological reference threshold used to assess the population.
The change has had a significant statistical impact because herring accounts for a substantial share of French landings. The species represented 8.5 percent of mainland French landings in 2023 and 9.2 percent in 2024.
As a result, the revised figures show that the proportion of fish landed from sustainably exploited stocks in 2023 fell sharply from an earlier estimate of 58 percent to 44 percent following the reassessment.
Researchers stress that such revisions are a normal part of the scientific process, as new data is incorporated and stock assessment models evolve.
Climate Change Raising Questions Over Fisheries Management Models
Alongside the stock assessment, Ifremer scientists have raised concerns about how environmental changes may undermine existing fisheries management assumptions.
European fisheries management has historically relied on the concept of maximum sustainable yield, the largest catch that a fish population can support over the long term without undermining its ability to reproduce.
That approach helped rebuild several previously overexploited stocks. The number of sustainably exploited populations increased from 18 out of 101 assessed stocks in 2000 to 80 out of 140 assessed stocks by 2024.
However, researchers warn that the traditional calculation of maximum sustainable yield assumes relatively stable environmental conditions, an assumption that is increasingly difficult to maintain.
Image: Ifremer
Youen Vermard, fisheries scientist at Ifremer and member of the advisory committee of the International Council for the Exploration of the Sea, said multiple environmental pressures are now affecting fish populations.
“Many populations are now showing signs of reduced capacity to renew themselves. These difficulties are linked to a combination of anthropogenic, climatic and environmental factors which together reduce the ability of exploited populations to complete their life cycle. Even when a population is classified as ‘in good condition’ today, insufficient productivity may lead in the short or medium term to a decline in exploitable biomass,” Youen Vermard, fisheries researcher at Ifremer and member of the ICES advisory committee, said.
Scientists Call for More Precautionary Harvest Targets
In response to these uncertainties, Ifremer researchers argue that fisheries management may need to adopt more precautionary exploitation targets.
They suggest that maximum sustainable yield should increasingly be treated as an upper limit rather than a target, with fishing pressure kept below that level to provide a buffer against environmental uncertainty.
One proposed benchmark would be exploitation at around 95 percent of the maximum sustainable yield level, which researchers say could increase stock biomass and improve resilience.
Clara Ulrich said the aim of fishing below the maximum sustainable yield would be to increase biomass levels and provide a margin of precaution against environmental variability.
“This proposal to fish below the maximum sustainable yield aims to increase the biomass of each fish population and thus improve their resilience by maintaining a precautionary margin in the face of environmental uncertainties,” Clara Ulrich said.
Researchers also argue that further reductions in fishing effort could align with long-term economic objectives by improving stock productivity while reducing impacts such as seabed disturbance, accidental bycatch and greenhouse gas emissions.
Mixed Picture in Overseas Coastal Fisheries
The report also examined coastal fisheries in France’s overseas departments, including Martinique, Guadeloupe, French Guiana, Réunion and Mayotte.
Scientific monitoring now covers 80 fish populations in these regions. Estimates suggest that 47 percent of landings in overseas coastal fisheries come from populations considered to be in good condition, while 20 percent originate from stocks that are both overfished and degraded.
However, the overall picture remains uncertain because around 27 percent of landings come from populations whose status is still unknown due to limited scientific data.
Lionel Pawlowski, fisheries scientist and co-coordinator of Ifremer’s overseas fisheries working group, said the share of stocks in good condition has remained relatively stable but that overfished populations appear to be deteriorating.
“If the share of populations considered ‘in good condition’ has remained stable at around 45 to 50 percent since 2013, the share of overfished populations has worsened, gradually shifting from ‘overfished’ to ‘overfished and degraded’, which indicates that their biomass is falling below the reference threshold,” Lionel Pawlowski, fisheries scientist and co-coordinator of Ifremer’s Overseas Working Group, said.
