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Fisheries

Should all shark fishing be banned?

Paper: Simpfendorfer, CA, Dulvy, NK (2017).  Bright spots of sustainable shark fishing.  Current Biology. 27:R83-R102.  doi: dx.doi.org/10.1016/j.cub.2016.12.017

Trivia challenge: try naming as many shark species as you can.  Though we tend to think of Great Whites, hammerheads and bull sharks, there are over 1,000 species of sharks and their cousins.  Not surprisingly, cartilaginous fishes such as sharks, rays and ratfish (from this point forward: sharks) are not created equally; every species has a diverse life history and ecological role.  This means some sharks are long-lived and reproduce every few years, while others have shorter life spans and reproduce much faster.  Likewise, some are apex predators and others are preyed on.

You’ve probably heard the shocking statistic that tens of million of sharks are caught and traded every year and a quarter of shark species are at risk of extinction.  So why do some scientists suggest that fishing for sharks should continue?

Sharks, tuna and barracuda at a fish market in Oman (Image credit: piknik via flickr, CC BY-NC-ND).

Sharks, tuna and barracuda at a fish market in Oman (Image credit: piknic via flickr, CC BY-NC-ND).

At first pass, it may seem like a no-brainer to ban the fishing, sale and trade of sharks; however, this blanket policy would not actually address the underlying circumstances.  For example, most sharks are caught incidentally in other fisheries (such as tuna).  Furthermore, shark fisheries provide food for many communities, so an outright ban may not be an effective solution.

Currently, around 7-9% (or 204,945 – 212,691 tonnes live weight) of global shark catch is biologically sustainable meaning that fishing rates do not exceed levels that would impact the natural state of the population (taking into account reproductive rate, growth rate and natural mortality rate).  In other words, shark fishing is already being done sustainably.

How can we get the other 91-93% of global shark catch on the path to sustainability?  Simpfendorfer & Dulvy put forth 5 management recommendations:

  1. Protect species with low reproductive rates such as deep water species (e.g. gulper sharks) or species with small litter sizes (e.g. bigeye thresher sharks, cowrose rays).
  2. Coordinate with international management bodies to set conservative catch limits for sharks with high biological productivity such as sharks in the high seas (e.g. populations of blue shark and shortfin mako).
  3. List commercially important sharks under international treaties.  For example, CITES (or The Convention on International Trade in Endangered Species) requires that internationally traded products do not endanger the survival of listed species in the wild.
  4. Nations with strong science-based fisheries management (e.g. USA, Canada, Australia and New Zealand) should share lessons and help other nations develop comprehensive management plans.
  5. Set up a traceability or labeling program for shark fisheries to allow consumers to identify and purchase sustainable products.  Sustainable shark fisheries can yield sustainable shark products–including shark fins.  In fact, 8.7% (or 4,406 tonnes) of dried shark fins are already sustainable, but they are not traceable or labeled.  If they were, consumers could choose to purchase these at a premium which could encourage more suppliers to follow suit.

Overall, this research shows that a simplified solution like a blanket ban on shark fishing is not a panacea.  Rather, species and location-specific management plans need to be developed to take into account the unique context of the shark population and fishermen.  If done properly, both biodiversity conservation and human food security can be strengthened, keeping both conservationists and fishermen happy.  

Discussion

4 Responses to “Should all shark fishing be banned?”

  1. Very informative article for ocean marine life conservation. Great work, Ms. Chen!

    Posted by Dr. Forest Redding, Jr., Ph.D. | March 4, 2017, 4:15 am
  2. This is a very good article, with just one error. Sustainability does not just depend on reproduction, but equally also on growth and the natural mortality rate. Sidney Holt

    Posted by sidneyholt | March 1, 2017, 9:43 am
    • Hi Sidney,

      Great point–growth rate & natural mortality rates certainly affects sustainability. The supplemental information reads:
      “To meet the criteria for biologically sustainable the stock assessment had to demonstrate that the current biomass was greater than that required to achieve Maximum Sustainable Yield (MSY) (Bcurrent > BMSY).” I took some ‘liberties’ on that since I didn’t want to unpack that in this article. However, the way you phrased it is perfect–simple and comprehensive. Thank you so much for taking the time to comment, I will make some changes!

      Posted by Megan Chen | March 4, 2017, 9:54 am

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