Saving Sharks: A Series – Conservation Categories

Humans like to categorize and label things. We like to list attributes and anything sharing those attributes go into that category or gets that label. Scientists and policymakers are particularly fond of doing this in an orderly fashion to help with decision making and to be fair, it is extremely helpful when studying and managing a diverse and chaotic natural world. But just a friendly reminder that we humans do not often agree on definitions or labels so as usual, confusion ensues.

When it comes to shark conservation, the category or label used by one state or nation, may not be the same used by another, even when they are talking about sharks of the same stock or population. Many people have heard of the International Union of Conservation of Nature (IUCN) Red List of Threatened Species categories (in order of extinction risk):

Source: IUCN Red List

These designations are incredibly important and are determined based on rigorous evaluation and research completed by impartial scientists using specific processes and criteria. The entire process and the list of species and their categories are available on the Red List website:

This information is used by scientists and policymakers to prioritize research and conservation efforts of those species in the threatened or data deficient categories. The IUCN Red List statuses for 37 species of elasmobranchs (sharks, skates, and rays) were recently updated in 2020 and it remains that about 25% of all shark and ray species are threatened with extinction. We now know that open ocean sharks have declined in population by a staggering 71% since the 1970s due to increased fishing pressures (Pacoureau et al. 2021).

However, these designations are not always recognized by governing bodies. For example, one of our major projects looks at the impact recreational fishing has on vulnerable species of sharks. We have focused on great hammerheads because they are listed as Critically Endangered by the IUCN and did not have a stock assessment despite making up a portion of the legal commercial harvest here in the United States. That justified our efforts to learn more about their interactions with a growing fishery but people are surprised to hear that this Critically Endangered species is part of the commercial harvest. This is because the U.S. department in charge of managing shark fisheries only recognizes U.S. designations. Great hammerheads are not Endangered in the U.S. because they are not listed on the Endangered Species Act. That listing is the only designation of Endangered that the U.S. recognizes.

Listing a species on the Endangered Species Act involves a very thorough application process, mostly driven by citizen petitions and meets the criteria for listing. Listing a species as either Threatened or Endangered under the ESA provides significant protections to that species throughout its U.S. range. Currently, there are very few sharks listed, oceanic whitetip (Carcharhinus longimanus) is listed as Threatened and only certain population segments of scalloped hammerheads (Sphyrna lewini) are listed as Endangered (see:

Each of these schemes of categorization or schedule of labels has its own processes and definitions and implications. It is as complicated as conservation can get but knowing there is a difference is very important when deciding how to help!

Pacoureau, N., Rigby, C.L., Kyne, P.M. et al. Half a century of global decline in oceanic sharks and rays. Nature 589, 567–571 (2021).

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