Nearly two-thirds of shark-meat samples tested in Switzerland and across Europe contain alarming levels of methylmercury, a potent neurotoxin, according to a new study. Much of the meat is sold under misleading names, such as roussette, saumonette, chien de mer or veau de mer.
A German laboratory analysed 44 samples of blue shark and seven of tope shark bought in supermarkets and restaurants in Switzerland, Germany, France, Britain and Spain, report the environmental groups ElasmOcean, Stop Finning Deutschland and the Gallifrey Foundation.
Methylmercury levels ranged from 0.22mg/kg to 4.40mg/kg. Twelve samples showed concerning concentrations (0.72–0.92mg/kg), while 17 exceeded the maximum limit of 1mg/kg set by the WHO, the EU and Switzerland for shark species.
A persistent poison
Methylmercury is a powerful and persistent toxin that accumulates in the body and attacks the nervous system. Chronic exposure can impair memory and coordination, cause irreversible brain damage in vulnerable individuals and, in extreme cases, be fatal.
As apex predators, sharks sit at the top of the marine food chain. They consume fish and other animals already contaminated with trace amounts of heavy metals such as mercury, lead and arsenic, as well as industrial pollutants like PCBs. These substances build up in tissue over time—a process known as bioaccumulation. Because sharks live long lives and eat contaminated prey, the toxins become highly concentrated in their bodies, through biomagnification.
Methylmercury binds to muscle proteins, making it particularly concentrated in the edible meat. Regular consumption of shark or other contaminated fish—once or twice a week—already exceeds the WHO’s recommended safety threshold.
Calls for tighter oversight
The foundation has alerted the Swiss authorities, including the Federal Food Safety and Veterinary Office (FSVO). The agency said that responsibility for quality control lies with the producer, importer and retailer.
One expert argues that the precautionary principle should apply. Consumers should first reduce fish consumption, she says, and Switzerland should next ban imports of all shark and ray products. Over the past 35 years, Switzerland has imported 609 tonnes of shark and ray products.
Care should be taken consuming other fish high in the food chain, such as tuna and swordfish.
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Report (in English)
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