The presence of mercury in the sea, driven by human activity, poses a real health concern for consumers. Some widely eaten fish such as tuna, swordfish, mackerel, and croaker are known to contain higher levels of this toxic element. Regular intake of these species is not advised, especially for pregnant women and young children. In contrast, many other fish offer very low mercury levels, making them safer choices for frequent cooking and meals.
Species like sardine, anchovy, sea bream, and squid often meet low mercury thresholds suitable for regular consumption, according to findings from the Institute for Environmental Diagnostics and Water Studies (IDAEA-CSIC). The European Union guidance reflects this by recommending fish and shellfish with lower mercury levels for routine eating.
The study, published in Environmental Pollution, examined more than 1,300 specimens across 58 fish species and shellfish commonly caught in the Mediterranean and widely sold in markets across Spain, Italy, and France.
The research identified 13 species that consistently showed mercury concentrations below EU safety limits. These include sardines, anchovies, blue haddock, carp (referred to in some translations as rage), sea bream, sea bass, red mullet, goby, croaker, salpa, dolphinfish, and squid.
Researchers noted that choosing these safer species can help minimize mercury intake while still delivering beneficial nutrients such as unsaturated fatty acids that support heart and brain health. The IDAEA-CSIC scientist cited, Joan O. Grimalt, emphasized that consumers gain nutritional value along with lower mercury exposure when selecting these fish.
Risks for Children and Pregnant Women
Experts cautioned that mercury is a toxic element capable of harming the kidneys, lungs, and both cardiovascular and nervous systems—effects that are of particular concern for expectant mothers and young children. Mercury can travel through water and air and accumulate in aquatic ecosystems, becoming concentrated as it moves up the food chain. It is absorbed by fish and other marine organisms and ends up in the seafood on many market shelves.
According to researchers monitoring markets in multiple coastal regions, most human mercury exposure through diet comes from fish and shellfish consumption. The study’s regional observations underscore the need for clear guidance on which species pose higher risks and which can be consumed more freely, especially by vulnerable groups.
Authorities should continue to monitor mercury levels in commonly sold seafood and issue practical health recommendations. In particular, guidance should highlight safe options for pregnant women and children, while recognizing that seafood also provides nutritional benefits when chosen thoughtfully. Grimalt underscored this balance and urged ongoing attention to mercury concentrations in high-risk species.
Note: the environment department continues to review data and publish updates as new measurements become available. The aim is to support informed choices that protect health without unnecessarily limiting access to nutritious seafood.
Environment department updates and studies contribute to a broader understanding of how mercury behaves in marine ecosystems and what it means for daily diets. The ongoing conversation seeks to align scientific findings with practical eating guidance that families can use at the market or in the grocery aisle.
Health authorities emphasize following local advisories and choosing seafood that adheres to safety recommendations while enjoying the nutritional benefits that marine foods offer.