Despite having a moral reason to not eat apex predators like sharks (discussed in a later blog), there is ample scientific evidence to support the claim that we should not be consuming organisms of the top trophic levels due to high heavy metal contents in the meat, important roles of these animals, and their life-history traits (reproductive rates, growth rates, etc.). Multiple statewide advisories for eating fish across the country recommend that people not eat any shark. Check out Florida and California advisories. The FDA even blankets all sharks as “do not eat” if you are pregnant, might become pregnant, are nursing or are a young child. We don’t know about you, but if something is clearly categorized as “do not eat for any type of human,” we want nothing to do with it. Programs like Monterey Bay Aquarium’s Seafood Watch list sharks as mainly “avoid," and only one species as “best choice" (Spiny Dogfish via bottom trawls on the West Coast of the U.S.). A great rule of thumb is to eat low on the food chain. 

Not too long ago (2013), a mako shark fished from Huntington Beach, CA was tested, and results revealed that its meat contained more than 100 times the legal seafood limit of PCBs, DDTs and mercury levels. This is an eye-opening find because mako shark is a common species of shark found in fish markets around the world. However, this species is now becoming exceedingly rare and is proposed to be added to the CITES endangered species listing. Toxin levels in Southern California are so high that officials have classified many top predators as “do not eat.” PCBs came to California when manufacturers dumped contaminated water in the sewers. From the 1940s to the 1980s, Montrose Chemical Company was dumping DDT-laced sewage in Southern California. This isn’t just a misfortune for fish in California. It happens around the globe. 

In the Bahamas (Florida, Gulf of Mexico, etc.), muscle tissue samples from 6 shark species were analyzed for metal concentrations (total mercury, lead, chromium, arsenic, cadmium, etc.), and the results reinforce the threat that consumption of this meat can harm human health, as well as the reality that humans are poisoning the oceans and the organisms within them, including the seafood they eat. Of the 6 species studied, the Caribbean reef shark had the highest concentrations of total mercury (THg), Arsenic (As), and Chromium (Cr). However, all species tested had very high concentrations of at least one type of metal. Even if humans were not to consume shark meat, these sharks may still suffer adverse effects as a result of the high quantities of metals found in their bodies.

According to WildAid’s findings in Sharks In Crisis, “a 2015 study of dusky, sandbar and white shark tissue samples taken from Australian waters found that 75 percent of dusky shark and 58 percent of sandbar shark samples exceeded the maximum mercury limits set by the FSANZ: Just two 120-gram servings of these species’ muscle tissue could exceed the provisional tolerable weekly dietary intake. The study also found [extremely high] concentrations of arsenic beyond acceptable limits in all muscle, liver and fin fiber samples from the three species. Additional studies have found shark fins with levels of arsenic exceeding 13 to 32 times China’s national guidelines. In November 2017, the Center for Food Safety (CFS) of the Food and Environmental Hygiene Department cautioned the Hong Kong public to avoid a batch of prepackaged shark’s tail skin after a routine test of a sample purchased in a Causeway Bay supermarket found that the product contained a level of mercury eight times the permissible limit - 4.16 parts per million (ppm) vs the 0.5ppm legal limit.”