Ocean warming, overfishing increase methylmercury toxin in fish

  1. According to a study published in the journal Nature, increase in sea temperatures and overfishing impacts the level of methylmercury in fish. Methylmercury concentration in fish has increased despite its decrease in seawater since 1990s
  2. The study observed there has been up to 23% increase in methylmercury concentration in Atlantic cod fish in the northwestern Atlantic Ocean. The increase has been due to changes in diet caused by overfishing. As a result of diet change, cod fish relied more on larger herring and lobster, which have higher concentrations of methylmercury.
  3. The study further noted that ocean warming causes changes in the methylmercury accumulation in fish. This is because fish metabolism is temperature dependent.
  4. The Gulf of Maine is one of the fastest warming bodies of water in the world. The researchers found that between 2012 and 2017, methylmercury levels in Atlantic Bluefin tuna increased by 3.5% per year despite decreasing emissions of mercury.
  5. Methylmercury is a harmful neurotoxicant. It causes central nervous system (brain and spinal cord) damage.