Yellowfin tuna have shown levels of increasing mercury toxicity. Mercury concentrations found in yellowfin fin tuna around Hawaii have been rising at a rate of 3.8 percent since 1998. Though, this may not be attributed only to ocean levels of the toxin. According to a study at the University of Michigan, the blame may lay in increasing levels of mercury in the atmosphere.
Mercury is a harmful toxin to humans and animals alike. It concentrates in the tissues of marine animals and poses a threat to those who consume large, predatory fish like tuna, swordfish, and other common fish found at the grocery store. In the ocean, mercury pollution is caused by atmospheric deposits from man-made pollutants from gold mining and coal-powered energy producers.
For the last few decades, scientists have estimated that open-ocean mercury levels in commercially-caught fish must increase in response to increasing atmospheric pollution. Though, the evidence needed for this hypothesis to be verified has not been observed or measured. Some scientists even say that mercury levels have not changed in years.
Paul Drevnick, a researcher at the University of Michigan, has collected and analyzed multiple published reports regarding yellowfin tuna caught off the coast of Hawaii. His team found that from 1998 to 2008 the level of mercury concentration in fish have risen at a minimum of 3.8 percent every year.
Drevnick stated that the message of these findings is that mercury found in yellowfin tuna is increasing as mercury concentrations increase in the Pacific Ocean. Open-ocean fish show that the atmospheric deposition of mercury pollution has caused this problem and the problem is rooted in man-made mercury emissions.
Carl Lamborg, a researcher at the Woods Hole Oceanographic Institution, said he is concerned about the levels of mercury found in tuna. Moreover, he explained that the troubling factor is that yellowfin tuna are not at the top of the food chain. Since the toxin levels are increasing at the middle range of animals in the food chain, it means the toxin levels found in larger, predatory animals is likely to be multiplied even further. Lamborg fervently stated that if the percent of mercury toxicity in yellowfin tuna keeps increasing year after year, soon all commercially-caught fish will be a danger for human consumption.
Though, there is cause to not be concerned. Levels of methylmercury, the organic compound of mercury found in open-ocean fish, that have been measured in yellowfin tuna does not seem to be dangerous for human consumption. According to researchers, the potential hazards of eating yellowfin tuna and other fish do not outweigh the health benefits of omega-3 acids and other benefits of a fish-enriched nutrition.
Levels of atmospheric mercury has increased by a factor of three during the industrial times of humans. Both researchers believe if mercury pollution in the atmosphere does not decrease, the levels of toxins in yellowfin tuna and other open-ocean fish will never go down. They stated that yellowfin tuna may be dangerous for humans to eat in the near future if mercury is on the rise.
By: Alex Lemieux
Picture: Beth Hoffman – Filckr License