1. Long Lifespan and Size (Bioaccumulation)
Sharks are long-lived predators. Over time, they
accumulate mercury—mostly in the form of
methylmercury, a highly toxic organic form—in their tissues by eating contaminated fish and marine organisms. This is called
bioaccumulation.
2. Top of the Food Chain (Biomagnification)
Mercury levels
increase up the food chain. Smaller fish ingest mercury from plankton and sediment, larger fish eat those fish, and sharks eat those larger fish. This process is called
biomagnification, and it results in very high mercury concentrations in apex predators like sharks.
3. Marine Pollution
Mercury gets into the ocean from:
- Industrial pollution (especially coal burning)
- Gold mining
- Wastewater discharge
It settles into the water and is converted into methylmercury by microorganisms. Fish absorb it through gills and diet, and it moves up the food chain.
Why It’s a Health Concern
Because of the high mercury levels, health organizations
advise against frequent consumption of shark meat—especially for
pregnant women and young children, as mercury can damage the developing nervous system.