Sharks have been villified for decades, with their fins being inspiration for countless horror movies. Although in reality, sharks are the real victims, experiencing mass population loss due to overfishing. Shark products are culinary delicacies and of cultural significance in many parts of the world; but identifying the species of shark within these products is tricky. Amid a mass extinction crisis, conserving endangered species must be a priority and identifying if and how they are being exploited is the first step.
Why should we care about sharks?
Sharks are under threat of overexploitation, with millions of sharks being killed annually for their fins (1). The global demand for shark products is skyrocketing, whether it be for meat or cosmetics. That’s right…The next time you put on some lip balm or foundation, check the label for squalene, a compound of shark liver oil (1). Sharks are a valuable commodity. Getting your hands on a bowl of shark fin soup is no cheap affair- with a portion worth between $50 to $200 and Amazon even offers Hammerhead shark jerky in the United States (1).
Over 100 million sharks are killed by people every year,
Greenpeace
Overfishing is one of the main drivers of shark overexploitation, with the abundance of oceanic elasmobranchs (sharks, rays and skates) declining by 71% since the 1970s (1). As well as being directly targeted for shark products, sharks are often victim of bycatch. Bycatch is when non-target species are caught in the fishing industry; these species are frequently discarded to make room for the more high-value species (2). Indeed, the billion dollar industry of shark finning consists of slicing the fins and discarding the rest of the shark carcass. Without their fins, sharks cannot swim and sink to the bottom of the ocean to die (2). As seen in the diagram below, fishermen prefer higher-value larger fins, known as the ‘primary’ set followed by the second choice, ‘secondary’ set fins (2). Although wasteful, the remaining low-value carcass would require space in holding vessels so is discarded instead (2). The seemingly unresolvable paradox between what is financially and environmentally feasible has resulted in these unsustainable fishing practices.
The role of sharks in the ocean ecosystem cannot be overstated. As mid-top-level predators, top-down removal of sharks can result in “trophic cascades” which can collapse a food chain (1). Sharks are especially vulnerable to overfishing due to their life history traits- being large, slow-growing, having a low fecundity, and maturing at a late age (3). Due to this, several species of shark have been included in regulatory lists aiming to protect against their trade but this has not slowed the ever-growing demand for shark fins (3).
How can we keep track of the problem?
By the time the fin ends up in a soup dish on a takeaway menu, it has been heavily processed and many diagnostic features to identify shark species have been lost. Thankfully, the boom in DNA sequencing has allowed for easier species classification in the absence of morphology (its visual attributes) (2).
Recently, metabarcoding has gained popularity to identify single species in multi-ingredient processed mixes. Many seafood products are labelled with generic terms like “white fish”, which takes away our ability to make an informed decision about which products to purchase (2). In fact, a barcoding study sampling pet food products from the United States found that 79% contained shark DNA. As seen below marked in red, a significant majority of the identified sharks were endangered (4). Sharks of conservation value were even found in cosmetics (4). The scariest part was that none of these products had shark listed as an ingredient.
Yes, DNA barcoding’s primary use is to identify mislabelled products but in the process, it brings attention to a much darker issue. The demand for shark products has become so widespread that a casual trip to the supermarket to buy some pet food may mean that you are involuntarily contributing to shark exploitation.
The future – can we ban shark fishing all together?
Whether there can be a ban on shark fishing completely is a touchy subject. Sharks have played a pivotal role in Chinese culture for centuries, with the consumption of shark fins linked closely to health and vitality (3). Shark fin soup in China would be exclusive to the richest families and indicated wealth and prosperity (3). In Hawaiian culture, sharks played a different role. Thought to be of spiritual significance, favoured persons of high status, usually men, were allowed to fish for reef sharks or hammerhead sharks for meat (3). The socio-cultural importance of sharks around the world conflicts with resource management of fisheries. Although banning shark fishing appears analogous to stripping away cultural traditions, if exploitation continues at its current rate, shark fin soup will vanish from menus regardless.
Sharks have been harvested past their limit, but many still ask if there could ever be a possibility of sustainable shark fishing. The answer is technically yes. Luckily, fishery experts have done the maths for us and by calculating maximum sustainable yield values to set catch limits, sustainable shark fishing is feasible (5). This, alongside correct labelling of seafood products can make moves towards more sustainable harvesting of sharks.
Shifting the perspective away from sharks as the Freddy Kruegers of the sea to realising that the health of the ocean relies on sharks is crucial.
If you want to learn more on how we can all do our bit, I urge you to take 5 more minutes out of your day to read this :
https://www.sharksider.com/10-easy-ways-help-save-sharks/: Is that a fish or some’fin else? How you may be buying into shark exploitation without realising it.Let’s work together to SOS (save our sharks)!!!
Reference List
1- Jarvis, Jason L. “Shark fin soup: Collective imagination in the transnational public sphere.” Global Media Journal: Canadian Edition 11.1 (2019)
2- Domingues, Rodrigo Rodrigues, et al. “From molecule to conservation: DNA-based methods to overcome frontiers in the shark and ray fin trade.” Conservation Genetics Resources 13.2 (2021): 231-247.
3- Dell’Apa, Andrea, M. Chad Smith, and Mahealani Y. Kaneshiro-Pineiro. “The influence of culture on the international management of shark finning.” Environmental management 54.2 (2014): 151-161
4- Cardeñosa, Diego. “Genetic identification of threatened shark species in pet food and beauty care products.” Conservation Genetics 20.6 (2019): 1383-1387
5- Porcher, Ila France, and Brian W. Darvell. “Shark Fishing vs. Conservation: Analysis and Synthesis.” Sustainability 14.15 (2022): 9548.
The Quagga 