This is the main conclusion of a study led by ICM-CSIC, which reports a drop of more than 60% in the local supply of this essential nutrient from fishing between 2000 and 2023.
Warming seas and overfishing have drastically reduced the availability of Omega-3 fatty acids in the Mediterranean, with direct implications for human health and marine ecosystems. This is revealed by a study published in Food Policy, led by the Institute of Marine Sciences (ICM-CSIC) and funded by the European Maritime and Fisheries Fund (EMFF) through the Costa Brava FLAG.
The research analyzed the lipid profile of nearly 3,000 individuals from 36 species caught along the Girona coast. The results show that Omega-3 supply, considered an essential component for human health and an excellent indicator of the condition of marine organisms, has fallen from 15 tonnes per year in 2000 to just 6 tonnes in 2023 — a decline of more than 60%.
“This is the first time we have quantified this decline in the Mediterranean, and the results are concerning. Climate change and fishing pressure have reduced both traditional fish populations and their capacity to provide Omega-3,” note Mar Vila and Sebastian Biton-Porsmoguer, co-authors of the study.
Decline due to overfishing and climate change
Temperate and cold-water species — such as sardine, anchovy, hake, or mackerel — have been the most affected. These populations, already depleted by overfishing, have also suffered from rising sea temperatures, which significantly disrupt ecosystem functioning and hinder recovery.
According to the study, although catches of warm-water species such as round sardinella or white shrimp — favored by warming — have increased, their Omega-3 contribution does not yet compensate for overall losses. In fact, the share of these species in Omega-3 supply rose from 3% of the total in 2000 to 27% in 2023, but the balance remains negative.
“The problem is not just the amount of fish caught, but also the composition of the catch. Species thriving under climate change cannot replace the nutritional value of those in decline,” explains Josep Lloret, ICM-CSIC researcher and study coordinator.
Over the 23 years analyzed, pelagic fish such as sardine and anchovy were the main suppliers of local Omega-3, accounting for 89% of total Omega-3 landings. Demersal fish such as hake or monkfish represented about 10%, while crustaceans and cephalopods such as shrimps and octopuses provided only 1%.
Health consequences
According to the General Fisheries Commission for the Mediterranean, only two of the ten species assessed in 2023 in the north-western Mediterranean were being exploited sustainably. In this regard, the European Environment Agency warns that, although European fisheries policy has managed to restore some stocks, the situation in the Mediterranean remains critical: only 1 in 10 stocks assessed by STECF is fished sustainably and remains in good condition.
This situation, combined with the reduction in Omega-3 production by phytoplankton due to warming seas — which negatively impacts the entire food chain up to fish — jeopardizes the future self-sufficiency of this essential nutrient in the Mediterranean.
International dietary guidelines recommend a daily intake of 250 to 500 mg of EPA and DHA, the two main marine-derived Omega-3 fatty acids. With the drop in local supply, meeting these needs will become increasingly difficult.
“We are facing a public health challenge. The lack of Omega-3 can increase the risk of cardiovascular diseases, certain types of cancer, and neurological disorders,” warn Angel Izquierdo and Joan San, physicians and co-authors of the study.
Solutions and opportunities
In response to this scenario, the scientific team proposes strengthening fisheries management to restore local populations and promoting the consumption of underutilized but highly nutritious species, such as round sardinella or bluefish. They also suggest making better use of Omega-3-rich by-products and prioritizing direct human consumption of fish instead of diverting it to fishmeal and fish oil for aquaculture.
“If we want to guarantee access to high-quality Omega-3, we must diversify species consumption and make the most of local fishery resources. Dependence on imports is neither sustainable nor desirable,” concludes the research team.
Although some plant sources such as walnuts or flaxseed can provide Omega-3, the authors remind that their form is less effective for health than marine Omega-3. The study therefore reinforces the need to preserve local fisheries as a key source of health and food security, acting with urgency and efficiency.