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Examining Scientific Integrity In the Global Shark Fin Trade

Shelly Clarke

"Selective and slanted use of information devalues and marginalizes researchers who are working hard to impartially present the data."

— Shelley Clarke

Where do you go to get your science?  This might sound like a strange question for those who are used to thinking of science as facts, immutable and uncontestable.  But I argue that just as we have all learned over the past decade that there is much to be aware of when making seafood choices, we also need to learn to be good consumers when it comes to our science intake as well. 

Let’s take the shark fin trade as an example.  When I began my PhD research on this topic in 2000, there was little scientific information about the trade and a low level of awareness among the general public.  While some shark fin traders were hostile, others did cautiously consent to provide me with samples and information.  I used this field data from the auction houses of Hong Kong and the shark ports of Taiwan to estimate, step-by-step, how many sharks of what species and sizes were passing through the world’s biggest market in Hong Kong each year.  I then extrapolated this to the global market and made a comparison to sustainable levels of fishing.  There were inevitably many unknowns in the formula, and being a scientist, I did my best to bracket these with high and low estimates and to carry through these unknowns as a range.  My conclusion was that as of 2000, the fins of 38 million sharks per year were being traded through the fin markets, but that the number could range as low as 26 million or as high as 73 million.

Shelly Clarke in boat

In 2011, with many conservation organizations escalating their campaigns and rhetoric against the shark fin trade, there are few news articles, web sites or blogs that don’t mention the millions of sharks killed each year.  But I almost never see any reference to the 38 million, which was after all, my best estimate.  Frequently I see “73 million” without any reference to this being my highest estimate, and almost as often I see “100 million,” an estimate that was published in Time magazine in 1997 but for which I can find no scientific basis.  Even more troubling, some sources quote these figures as “the number of sharks killed for their fins”, or “the number of sharks finned” (carcasses discarded at sea), or the “number of sharks finned alive” every year.  The truth is that no one knows how many sharks are killed for their fins, how many have their carcasses dumped at sea, or how many sharks are alive when finned.  We simply don’t have that information, nor do we know whether these numbers have been sustained every year since 2000. 

I’m inevitably interrupted at this point by the question “Who cares about the actual number anyway?”  We all should.  First, we should seek to ground our positions on these issues in the best available science.  Selective and slanted use of information devalues and marginalizes researchers who are working hard to impartially present the data.  Second, unless our aim is to prohibit killing all sharks worldwide, we need to know how many sharks can be killed without damaging the long-term sustainability of shark populations and ocean ecosystems.  These numbers are hard to calculate and getting accurate estimates of current shark catches, using fin trade data if necessary, is incredibly important to fisheries management.  Third, exaggeration and hyperbole run the risk of undermining conservation campaigns.  Presenting a high but scientifically unsubstantiated number like 100 million can discredit otherwise valuable advocacy for better resource management and monitoring. 

What can we do to become better science consumers?  My advice is to apply the following tests to the science on your daily menu: 

  • Is the name and affiliation of the original research team mentioned?  If not, the opportunity to verify the information is more limited, thereby opening the door for misrepresentation. 
  • Was the research team independent?  If not, the study may have been conducted to support a particular conclusion. 
  • Did the researchers invest time in gathering new data from a reliable source themselves?  If not, there may be a greater chance that they have misinterpreted signals in the data. 
  • Does the article mention whether the study was published in a peer-reviewed journal?  If not, there may not have been sufficient independent checking of the results. 
  • Does the article present any shortcomings or weaknesses in the study?  If not, it may be a press release from a proponent organization rather than an objective summary of the findings. 

Choose carefully, and bon appétit!


Shelly ClarkeShelley Clarke received her doctorate in quantitative fisheries science from Imperial College London in 2003 for her ground-breaking study of the shark fin trade. She first acquired her interest in the marine environment while growing up in the lobster fishing town of Winter Harbor, Maine, but an observer assignment aboard a Japanese mothership and Luce Foundation fellowship took her to Japan and China where she has been based for the last 20 years. Shelley believes that East Asia, as the home of the world's most powerful fishing fleets and the largest and fastest-growing seafood markets, exerts a tremendous, but often overlooked and widely misunderstood, influence on the world's oceans. By applying her scientific skills while immersing herself in the rich traditions and languages of these two cultures she hopes to contribute to better understanding and dialogue on sustainable utilization of global fisheries resources.