F’in Hell! – Implications of the shark fin trade

“The Shark fin soup, Sir?” is not a common phrase you would hear in a London restaurant, but in some parts of the world it is a delicacy, a tradition and a dietary staple. China has emerged as the largest market for the shark fin and meat industry. Iceland have a unique delicacy known as Kæstur Hákarl, which is fermented and dried shark skin. It’s an acquired taste to say the least. Many island communities around Asia and in the South Pacific rely on shark meat for sustenance as well as money to support their families. But the darker truth to these traditions is the damage that the industry has been doing to shark populations and the marine ecosystem.

History of Sharks and the Fin-dustry

Sharks have been around for 450 million years, 200 million years before dinosaurs, appearing in a variety of shapes and sizes. They haven’t changed that much over the last 100 million years, although they have gotten smaller, and they have evolved their physiology and behaviours to become the ultimate apex predator we have today (Figure 1).  Made up of light and flexible cartilage that grows with the shark, covered in tooth-like denticles on the skin that can vary in shape and orientation to improve swimming ability, they have evolved to be a stream lined and fast hunter. For a few hundred millions years the biggest threat to sharks was another shark, and dinosaurs for a while, that was until humans began to evolve and increase.

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Figure 1: The ultimate predator: The Great White Shark (photo: PA)

The shark fin trade has been a part of Chinese culture since the Han Dynasty, over 2200 years ago, not only is it considered a delicacy but it has been attributed to many medical cures. Estimates of between 26 and 73 million sharks are killed every year for theirs fin and as by-catch in the fishing industry [1], although this number could be higher as illegal fishing activities and falsified by-catch records make it hard to assess the actual number.

The threats and Effects

Through studies into shark populations, recent estimates indicate that exploitation has depleted their numbers worldwide by at 90% over the last 50 to 100 years [2]. Yet the impacts from the evident population depletions and indirect effects on the marine ecosystem of this predator removal remains unpredictable [3]. Certain shark species feed on other elasmobranch species. Increases in the shark fishing industry have led to an increased removal of these shark species (Figure 2), causing a restructuring of marine communities [4].  Exploitation of these Great Sharks had intensified worldwide from the late 1970’s [3], driven by an upsurge in demand for shark products.

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Figure 2: The decline in the main shark populations that are targeted by the fin trade industry, data taken from the early 1970’s to 2004 [3]

With sharks being the top predator, occupying the highest trophic level in the marine environment, their removal can cause a cascading effect on the lower mesopredator populations and food web structure [3].  A case study of such a cascading effect as a result of shark removal on community structure is that of cow-nose rays and scallops in the Atlantic (Figure 3). The decline in Black Tip Shark numbers off the east coast of America lead to an increase in cow-nose rays numbers; the predominate food source of black tip sharks. The cow-nose rays feed on scallops which are largely farmed around the east coast, with this increase in ray numbers the scallop numbers started to decline [4].

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Figure 3: Showing how the decline of the Black Tip Shark (a) caused the Cow-Nose Ray (b) populations to increase as predation pressure lessened, causing the scallop populations (c) to decline, cause and effect of predator removal [4]

Reading the IUCN’s Red List, 141 of the 440 known shark species are listed as Endangered or Critically Endangered, with the greatest threat coming from shark finning and fishing industries. Studies undertaken over the last 8 to 15 years into shark populations have shown that, across the species, they have declined by more than 50% [5], this is mainly due to exploitation.  The concern is that the magnitude of these declines across all shark species could cause local extinction of those species that are targeted most for the fin trade.

A key factor in figuring out the true numbers of shark population lies in developing countries where local fisheries authorities have little interest in products that are dried out, most barely have the capacity to monitor fishery products that are local caught or not caught by domestic fishermen [1].

Changing Tides

Over the past decade awareness and conservation efforts, particularly across Asia, have meant that views of the shark fin trade are starting to change and the activity pressure to be reduced on shark populations. An assessment run by the organisation Wild Aid in China it showed an 82% decline in sales by shark fin vendors and a decrease in prices of the meat between 2010 and 2012. Online surveys showed that 85% of consumers in China said they gave up shark products because they thought it was cruel; they want to protect the sharks; and that local campaigns on conservation and awareness had made them rethink the use of shark products [1].

Stronger measures still need to be put in place to protect the sharks, but the main hurdle is the global expanse of shark distributions. The conservation efforts need to look into areas key to shark species for habitat, mating sites and feeding sites. Areas where large numbers of sharks congregate and can be vulnerable. The study by Baum et al in 2003 looked at differing conservation efforts and complications with marine protected areas for sharks [5]. The decline of the shark fin trade is one major step into reclaiming shark populations, yet further efforts need to be taken to preserve these mighty predators.

References

  1. Wild Aid. 2015. Evidence of Declines in Shark Fin Demand, China. Report.
  2. Myers, R.A. and Worm, B. 2005. Extinction, Survival or Recovery of Large Predatory Fishes. Phil. Trans. R. Soc. B. 360, 13-20. (doi:10.1098/rstb.2004.1573)
  3. Myers, R.A., Baum, J.K., Shepherd, T.D., Powers, S.P., Peterson, C.H. 2007. Cascading Effects of the Loss of the Apex Predatory Sharks from a Coastal Ocean. Science. 315, 1846-1850.
  4. Heithaus, M.R., Frid, A., Wirsing, A.J., Worm, B. 2007. Predicting Ecological Consequences of Marine Top Predator Declines. Trends in Ecology and Evolution, 23, 203-210. (doi:10.1016/j.tree.2008.01.003)
  5. Baum, J.K., Myer, R.A., Kehler, D.G., Worm, B., Harley, S.J., Doherty, P.A. 2003. Collapse and Conservation of Shark Populations in the Northwest Atlantic. Science. 299, 389-392.
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