By Sandy Sawh
The next time you are thinking of buying the popular Bake and Shark sandwich consider this…chemical pollutants, just like plastics, are pervading our food chain and toxicity levels are highest in large oceanic predatory fish such as sharks, groupers and barracudas.
“Chemicals are substances or compounds that have been purified or manufactured by humans, it does not include elements that are part of the normal life processes of plants and animals1.”
There are three main pollutant categories that contribute to chemical toxicity: toxic metals from industrial estates and waste dumps, persistent organic pollutants (POPs) mainly from the agricultural sector and lastly, accidental oil spills. Commercial and recreational shipping activities are also considered significant contributing factors. Unfortunately, in Trinidad and Tobago preliminary studies indicate that there is a specific risk of sharks being contaminated with mercury from gold mining activities in South America. While difficult to quantify these are just some of the dangers seeping into our aquatic environment and at most times hidden or unseen.
These pollutants can go undetected for a considerable length of time, the seafood we consume tells a different story. Largely due to bioaccumulation and biomagnification, the shark you eat can be heavily contaminated with a variety of toxins. Bioaccumulation and biomagnification, are two different processes that often occur in tandem with one another. Bioaccumulation is the process by which toxins build–up in individual organisms increase as they age or by consuming multiple contaminated food sources, while biomagnification is the process by which toxins are passed from one trophic level to the next increasing at each level in the food web2.
Researchers from the Shark Research & Conservation Program at the University of Miami indicated that these processes “will result in the top predator containing the highest concentration levels”3 of toxins. Sharks are particularly susceptible to contamination uptake and bioaccumulation due to their long- life spans, high position in a food web and large, lipid-rich livers4. Over time, the frequent consumption of shark may negatively impact your health. Dementia, increased risk of cancer, and infertility are just some of the effects associated with the consumption of these toxins.5
There are several steps you can take to reduce your risk, the easiest and most obvious would be to simply stop eating sharks and other globally endangered species. Now at this point you are probably wondering, what should I eat? Thankfully, there are a variety of sustainable seafood guides that could help you decide, take a look at:
- The Environmental Defense Fund, they allow you to search their database and evaluate each type of seafood against its eco-rating (sustainably caught or farmed) and its mercury level. It also provides a concise list of best and worst choices.
- For a more Caribbean specific list of sustainable choices, Nazma Muller at the Caribbean Beat provided this handy guide along with a variety of justifications for not consuming sharks.
We hope that the next time you take a trip to the North Coast and approach your favourite bake and shark vendor you will make sustainable and safe choices for you, your family and for our environment.
1http://www.oceanhealthindex.org/methodology/components/chemical-pollution
2https://cimioutdoored.org/bioaccumulation-and-biomagnification-increasingly-concentrated-problems/
3https://sharkresearch.rsmas.miami.edu/bioaccumulation-biomagnification-when-bigger-isnt-better/
4Mull, C.G., Blasius, M.E., O’Sullivan, J.B., Lowe, C.G. 2012. Heavy metals, trace elements, and organochlorine contaminants in muscle and liver tissue of juvenile white sharks, Carcharodon carcharias, from the Southern California Bight. In Global perspectives on the biology and life history of the white shark (pp. 59-75). Domeier, M.L. Boca Raton, FL: CRC Press.
