Why sharks can be so toxic: bioaccumulation and biomagnification
Marine organisms absorb and cannot excrete some toxins and heavy metals that enter the oceans from pollutants. These toxins accumulate in a fish’s body as it eats other fish, known as "bioaccumulation1," and travel through the food web from prey to predator, continuing to increase in density in a process called "biomagnification2."
At the top of the food chain are the ‘apex’ predators: sharks. Some shark species can live for 50 years or more, consuming many toxin-laden fish and storing those toxins in their bodies throughout their lifetime. When we eat shark fin soup, we are consuming their toxins, too.