Rise in Accumulations of Methyl-mercury toxin in Fish

Contrary to the conventional wisdom that the reduction of methyl-mercury contaminants in the seawater, studies have found that the rise of the dangerous toxins in the fish has increased.

Why has this happened?

  • Researchers have claimed that the general increase in the rise of methyl-mercury toxins in the fish can be attributed to the two factors- ocean warming and dietary shifts in fishes due to overfishing caused by increasing human consumption.
  • Particularly, in codfish, the rise of methyl-mercury can be directly attributed to the overfishing which was a result of greater demand for codfish in global markets.
  • Data of the past 30 years has been analyzed by researchers and it has shown that a 23% increase has been observed in the concentration of methyl-mercury in the codfish found in the Atlantic Ocean.
  • Contrarily, a decrease of 33-61% reduction in the concentration of methyl-mercury has been observed in the spiny dogfish between the years 1970-2000s.
  • While the codfish feed on herrings and lobsters rather than other small fishes while the spiny dogfish feeds on squid and cephalopods.
  • Herrings and Lobsters have a higher accumulation of mercury in them.?
  • The concentration is also dependent on ocean temperatures which are rising globally.?
  • It is observed that human exposure to toxins through fish consumption will increase due to rising consumption and due to climate change.

Effect of Mercury on Humans

  • Prolonged exposure and consumption of mercury have been found to cause Mercury poisoning.
  • The symptoms of mercury poisoning include muscle weakness, poor coordination in the digits & limbs, high level of numbness in the hands and feet, rashes on the skin, anxiety, memory problems, trouble speaking, trouble hearing, or trouble seeing.
  • If there is a high level of exposure to mercury, it is known as Minamata disease.
  • Exposure to Methylmercury in small children causes acrodynia (a pink disease which makes the skin look pink and peels).
  • Other effects include kidney problems and decreased intelligence.


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