Mercury in Fish

Mercury in the Environment

Mercury is a naturally occurring element found in the Earth’s crust, where it poses no great risk to human or animal health. However both natural occurrences, and human activities can release mercury into the environment. The accumulation of mercury in the atmosphere and bodies of water poses a risk to human health.

Artisanal and small scale gold mining is responsible for the majority of mercury pollution found in the environment today. Mercury is commonly used by artisanal miners to extract gold from ore, as Mercury is readily able to attach to gold to form an amalgam, the mercury is then vaporised leaving only the gold behind. This technique is popular due to the ability of mercury to attach to very small gold particles in mined sediment, however it poses great health risks to those who work with it and for the environment it contaminates. Whilst today there are much safer techniques for mining gold, artisanal and small scale miners continue to use mercury due to their lack of funds and capacity to employ safer measures, as such mercury continues to flow into the Earth’s ecosystems.


The Minamata disease is central to understanding the importance of researching mercury in fish. Minamata disease refers to a neurological disorder caused by severe mercury poisoning. The first case of the disease was found in a young girl in Minamata City, Japan. Her symptoms initially puzzled physicians, and it was not long before many other similar cases began arising in the region, mostly occurring people living in fishing communities.

The disease is known to cause sensory disturbances, tremors, ataxia, numbness, muscles weakness, dysarthria and can be passed on to fetuses in pregnant women. In serious cases mercury poisoning can cause brain lesions, paralysis, insanity, and ultimately death.

Industrial wastewater released from the Chissco Corporation’s chemical factory in Minamata was eventually found to be the cause of the mercury pollution. The mercury in the wastewater had bio accumulated in fish and shellfish Minamata Bay and Shiranui Sea, those consuming large amounts of the contaminated seafood inevitably developed symptoms of the disease.

The fallout of the Minamata disatser led to a real concern for the effect of mercury in seafood throughout the world. Since the disaster numerous studies have documented the presense of mercury in ocean sediments, seawater, animals, and humans.

MSI Mercury Database and Interactive Map

Various researchers across the world have documented the presence of Mercury in fish, seawater, and ocean floor sediments. At MSI, in collaboration with Sydney Informatics Hub and GRID Arendal we have developed a database of studies investigating mercury in fish, ocean sediment and seawater. You can explore the data here.