A scientifically accurate list of the most endangered sharks in the world

One of the most common questions I get during my “ask me anything” sessions on twitter is “which species of sharks are the most endangered?” Whenever I can’t completely answer a question in a single tweet, I like to link to more information from a reliable source.

However, I’ve struggled to easily answer this question with a link, because much of the information out there about this particular question is incomplete, misleading, or just wrong.  Several online lists of the most endangered species of sharks* don’t actually include the most endangered species of sharks. Many of these lists could be re-titled as “the conservation status of some species of sharks I’ve heard of and could easily find pictures of” or “some random information I heard out of context about shark conservation.” Since there isn’t an easily accessible source of accurate information about this important shark science and conservation topic, I’ll make one myself. ( I should note here that I am referring only to true sharks, not to other chondrichthyans, even though other chondrichthyans in many cases face similar or worse threats. )

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How severe are shark population decreases, and how do we know?

John Shepherd once said that counting fish is like counting trees, except that fish move and you can’t see them because they’re underwater. This is true with sharks as well. It’s basically impossible to know how many sharks there are. Fortunately, a variety of methods exist that can be used to determine population trends. In other words, even if we can’t know how many sharks there are, we can tell if there are more or less than there used to be. Presented here are brief descriptions of some of these methods and the conclusions of major shark conservation studies that used them. Though no one method is perfect, the fact that so many different methods have such similar conclusions is quite telling.

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