• SharkieSophie

Toxic Soup

Updated: Apr 26

In the past, conservationists have focused on the emotional and ethical aspects of shark finning to garner support for finning bans. We talk about the cruelty of cutting off the fins whilst the shark still lives, and we educate about the ridiculous waste from finning practices and the potential ecosystem damage from "trophic cascades" if sharks die out. However, as shark finning is still rampant around the world, scientists are now discussing the potential health impacts of shark fin soup. Could a threat to human health be the secret to reducing the global demand for shark fins?


Shark fins on board a commercial fishing vessel (Image source: www.cmi.sdsu.edu)

Shark fin soup is a delicacy in certain Asian countries, especially China, and amongst other Asian communities around the world. It is considered a status symbol, as it has been been associated with the aristocracy since the Song Dynasty. The dish is traditionally served to guests, in line with good hospitality practices. Whatsmore, Eastern medicine erroneously maintains that consumption of shark fins has health benefits, so the soup is believed to imbue good fortune.

Shark fin soup (Image source: www.wikipedia.org)

But shark fin soup has certainly not brought good fortune to shark populations worldwide. It is estimated that as many as 73 million sharks are fished every year for their fins. Alongside other threats (check out my article Threats to the Fin to learn more), overexploitation from finning has driven shark populations to drop by as much as 70% globally, with certain species suffering declines closer to 90%. The International Union for the Conservation of Nature (IUCN) now classifies at least 10% of all shark species are as ‘vulnerable’ to extinction, almost 5% are classified as ’endangered’ and more than 3% as ‘critically endangered’. This means they have declined so dramatically that they may go extinct in the very near future (IUCN, 2020).



Thankfully, public attitudes to shark fin soup have been changing in recent years, with the modern notion that shark finning is extremely unsustainable, unethical and cruel. Sharks must now be landed with their fins attached in several nations, including Canada, the UK, South Africa, the USA, New Zealand, the UAE, Hong Kong and China, amongst others. Shark fin soup has also been banned within several companies, including Amazon, and the Marriott and Hilton Hotel Groups. Many transportation and/or logistics companies refuse to transport shark fin cargo, including Virgin Atlantic, Quantas, Emirates, and UPS (see the full list). Public pressure has also forced shark fin soup to be removed from the menu at several state dinners and large events in China.


Protest against shark fin soup in China, 2016 (Image source: https://www.maritime-executive.com)

However, whilst shark conservation efforts are increasing world-wide, there are serious concerns that it will be too little, too late. Therefore, some scientists are now focusing their attention on how shark fin soup might be damaging to human health...


For example, a recent study analysed the toxic metals in shark fins for sale at Hong Kong markets. The researchers found that in all 80 species of sharks they analysed, mercury (chemical symbol Hg) and methyl-mercury (MeHg) levels in the fins exceeded the safe limit established by Chinese health authorities. Whatsmore, they found that certain species, such as the blue shark (Prionace glauca) also exceeded the safe levels of arsenic (As). Both mercury and methyl-mercury are toxic to the humans, as ingestion in high doses can cause neurological and behavioural disorders, and serious organ damage. Ingestion of mercury during pregnancy can also adversely affect the development of the baby’s nervous system. Arsenic is extremely toxic to humans; it can cause death in high doses and even low-doses can cause multiple different forms of cancer, if exposure occurs over extended periods (Barcia et al, 2020).


Toxic chemicals in shark fins which exceed safe consumption limits (Barcia et al, 2020)

Other studies have focused on the levels of β-methylamino-l- alanine (known as BMAA) in fins of sharks. A study performed in Miami found that 80% of the samples contained BMAA concentrations which were within the range which is suspected to be seriously toxic (Mondo et al, 2012). Similarly, another study found that these toxins were prevalent across all the shark species they sampled in the South Atlantic and Pacific Oceans (Hammerschlag et al, 2016). These levels have been found previously in the brains of victims of neurodegenerative diseases and BMAA is implicated in contributing to amyotrophic lateral sclerosis (ALS), Alzheimer's and Parkinson’s disease. The scientists advised that consumption of shark fins or meat would increase exposure to BMAA and could have serious health implications.


Toxic BMAA in different shark species (Hammerschlag et al, 2016)

Human health is generally of great interest to the general public. If the Covid-19 pandemic has taught us anything, it is that public health scares garner considerable media attention and are of serious concerns to governments. Therefore, highlighting the serious health risks from heavy metals and neurotoxins present in shark fin soup could be a very effective method to reduce the consumption of shark fins on the global market. This could be a very promising avenue for shark conservation in the future.


If you would like to get involved in supporting the movement against shark finning, you can join campaigns with:


If you would like to learn more about the problems associated with shark fin soup, you can check out Neil Hammerschlag’s wonderful TED talk:



References

Barcia LG, Argiro J, Babcock EA, Cai Y, Shea SKH & Chapman DD (2020). Mercury and arsenic in processed fins from nine of the most traded shark species in the Hong Kong and China dried seafood markets: The potential health risks of shark fin soup. Marine Pollution Bulletin, 157, doi: 10.1016/j.marpolbul.2020.111281.


Hammerschlag N, Davis DA, Mondo K, Seely MS, Murch SJ, Glover MB, Divoll T, Evers DC & Mash DC (2016). Cyanobacterial neurotoxin BMAA and mercury in sharks. Toxins, 8:8, 238. Access online.


Holtcamp W (2012). Shark fin consumption may expose people to neurotoxic BMAA. Environmental Health Perspectives, 120:5, doi: 10.1289/ehp.120-a191.


IUCN (2020). International Union for the Conservation of Nature Red List of tHreatened Species. Access online.


Mondo K, Hammerschlag N, Basile M, Pablo J, Banack SA & Mash DC (2012). Cyanobacterial neurotoxin β-N-methylamino-L-alanine (BMAA) in shark fins. Marine Drugs, 10, 509-520. Access online.


By Sophie A. Maycock for SharkSpeak.

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