Introduction

There is mounting evidence regarding the effects of weather and climate on economic outcomes such as agricultural output, labour productivity, and economic growth. However, this empirical literature has largely overlooked the ocean despite its central role in both climatic and economic systems. Marine fisheries generate hundreds of billions of dollars in revenue globally and support more than 62 million jobs worldwide. This paper addresses this research gap by providing the first causal estimate of the effect of ocean temperature on marine fisheries revenue. The researchers leverage a novel, high-resolution dataset including more than 2.5 million observations of annual, spatially-located fishing revenue between 2013 and 2022, spanning the Atlantic Ocean, the Arctic, and the Mediterranean Sea.

Data

The study constructs a unique dataset by integrating several information sources. Fisheries revenue data were obtained from the Scientific, Technical, and Economic Committee for Fisheries (STECF) of the European Union, which reports catches and ex-vessel revenue for all EU fishing vessels. These data were merged with satellite sea surface temperature (SST) from the National Oceanic and Atmospheric Administration (NOAA). To quantify species-specific exposure, the researchers developed a novel metric called Marine Degree Day (MDD). This indicator cumulates exposure to temperatures outside the preferred thermal interval of each species, creating two annual indexes: MDD+ for heat exposure above the thermal range and MDD− for cold exposure below it. Biological information for 100 commercially important species was sourced from FishBase and SeaLifeBase repositories.

Theoretical model

The empirical specification is underpinned by a stylized bio-economic model that links ocean temperature to fishing revenue through fish population dynamics. In this model, temperature shifts local habitat conditions and changes the carrying capacity of the environment. A change in carrying capacity alters biological growth and the evolution of biomass over time, which affects the sustainable harvest rate and revenue. The model assumes that fisheries management objectives under the EU Common Fisheries Policy (CFP) aim for maximum sustainable yield (MSY), where the target biomass is half of the carrying capacity. This structural framework allows the researchers to link temperature changes to revenue even when fish stocks are not directly observed.

Empirical specification

The baseline model estimates the marginal revenue response to cold and heat exposure using a high-dimensional fixed-effects specification. These effects absorb determinants of revenue that vary at the cell-by-year-by-technology level, such as fisher selection and effort, as well as shocks common to a management region, such as price conditions or regulatory constraints. The model was extended to include habitat suitability controls, such as bathymetry, terrain rugosity, and salinity, and to account for trophic interactions. To address temperature-induced ecological spillovers, the study developed the Heat Exposure of Aquatic Trophic Exchanges (HEATEX) index, which measures the average thermal exposure of trophically connected species.

Main results

The results indicate that departures from a species’ preferred temperature range generate significant and asymmetric damages. Both heat and cold exposure reduce fishing revenue, but the estimated impact of heat exposure is approximately three times stronger. A 100-unit increase in MDD+ decreases revenue by approximately 15%, while an equivalent increase in MDD− leads to a 4.7% reduction. To provide a sense of magnitude, the researchers highlight the Atlantic mackerel, which generates the highest aggregate revenue in the sample. A 15% increase in heat exposure for this species, consistent with mid-century climate projections, would reduce annual revenue by approximately €24 million.

Robustness tests

The findings remained coherent across a broad set of robustness checks. To address potential sample selection bias where zero revenue is not observed, the researchers constructed a set of 1.8 million “implicit zeros” for species feasible to catch but absent from landings. The estimates remained consistent when using Poisson Quasi-Maximum Likelihood (PQML) and calibrated log transformations. Spatial spillover tests involving the progressive aggregation of the spatial grid suggested that the results are not driven by the reallocation of fish across neighbouring cells. Other checks confirmed that results were stable when excluding endangered species, highly migratory species, or catches taken outside the EU Exclusive Economic Zone.

Non linearities and heterogeneous effects

The revenue response is strongly non-linear regarding heat exposure. Moderate heat exposure (within 5°C of the threshold) is associated with an approximately 4% decline in revenue per 100 MDD, whereas extreme heat exposure (more than 5°C beyond the threshold) is associated with a revenue loss of approximately 30%. Significant heterogeneity was also documented across ecological groups. Demersal species appear particularly vulnerable to both warming and cooling. Conversely, a species’ vertical mobility potential (VMP) was found to moderate the effect of heat anomalies, as species can exploit vertical temperature gradients to buffer thermal stress. Most of this attenuation occurs once species have access to at least 100 metres of feasible vertical range.

Climate change projections

Combining the estimated dose-response function with daily SST projections through 2100 points to widespread revenue declines. Under the most pessimistic emission scenario (SSP-3.70), median losses are projected to reach 12% by the end of the century, with annual aggregate losses of approximately €560 million. Under the intermediate SSP-2.45 scenario, projected annual losses reach €430 million. These impacts are highly spatially heterogeneous; tropical and subtropical waters exhibit large projected losses, often exceeding 30% relative to the baseline. In contrast, some high-latitude regions may experience revenue gains due to reduced cold exposure. This pattern highlights a marine dimension of climate inequality, with the largest losses concentrated in lower-income equatorial areas.

Discussion and conclusion

The research demonstrates that ocean temperature variations have a causal impact on fisheries revenue by affecting carrying capacity and stock biomass. The findings show that heat exposure becomes especially damaging when temperatures exceed the upper bound of the thermal range by a large margin, highlighting the risks posed by marine heatwaves. While vertical mobility and ecological resilience offer some mitigation, the overall trend points to negative aggregate impacts under future climate scenarios. Policy implications suggest that management should facilitate adjustment through flexible quota allocations and incentives to diversify target portfolios, particularly in regions facing significant climate-related risks.