By Todd Steiner
A new study out of Harvard and the University of Delaware published in the Proceedings of the National Academy of Sciences (https://www.pnas.org/doi/10.1073/pnas.2405898121) document that industrial fishing supplies 70% of poisonous methylmercury consumed by the public. The highest level of methylmercury is found in tuna and other large fish from tropical and subtropical waters, the target species of industrial fishing.
Methylmercury is a neurotoxicant that impairs development in fetuses in utero and infants (through seafood eaten by their mom’s during pregnancy), or children directly eating tuna and other fish. It is also known to impact cardiovascular health in adults.
Mercury makes its way into the food chain through of coal-fired power plants, waste-incineration, industrial processes, and mining, and is bio-accumulated in large, long-lived predatory fish. Large-scale industrial fisheries target these top predators that occur in warm tropical waters where methylmercury levels are highest.
The researchers also noted that the healthy micronutrients found in fish, like omega-3 fatty acids, are lowest in seafood harvested in these warm waters, now being exacerbated by climate disruption causing warmer ocean temperatures.
The study also noted that poor subsistence small-scale fishing communities are paying the price of pollution created by the industrialized world, and these communities are likely to exceed methylmercury exposure thresholds recommended by the World Health Organization and FDA because of their reliance on fish in their diet.
If you do eat fish and want to protect your health, scientists recommend eating small fish, such as sardines, anchovies and herring, which have much lower concentrations of methylmercury and are much higher in omega-3 fatty acids.
To calculate your mercury exposure from eating fish, use TIRN’s free mercury calculator found at https://seaturtles.org/whats-the-catch-calculator/
