Overfishing to Shark Fins: Blue Sharks Get the Blues

Shark Stewards is campaigning for CITES Appendix II listing of blue sharks, (Prionace glauca) in Panama 2022. After blocked for listing by major shark fishing nations Spain and the USA at Cop18 in 2018, blue shark population continue to slide along a rapid decline due to bycatch and the shark fin trade.

About Blue Sharks

The blue shark is a highly migratory species found in tropical, subtropical, and warm-temperate waters around the globe, both on the high seas and within EEZs.

The blue shark is the most heavily fished shark in the world (Compagno et al. 2005) with annual global catch estimates of around 20 million individuals each year. This species is rarely targeted commercially but bycatch by longline and driftnet fisheries is very high. A global species occupying neritic habitat, these sharks occur in the Atlantic, Pacific and Indian Ocean. This wide ranging, and highly migratory species, is found from 50º N latitude to 50ºS latitude in both inshore and offshore waters. 

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These sharks take up to seven years to mature and can have up to 68 pups per litter. Their reproductive rate is higher than that of many shark species, but are declining globally.

Although relatively fecund, this once abundant species is being fished at or beyond the Maximum Sustainable Yield, not considering the Illegal, Unreported and Unregulated catch on the high seas.

As the most common shark traded in the Hong Kong and mainland Chinese shark fin trade (#1 and 2 , representing around 70% of all global trade), these sharks are facing a grim future. Without increased fisheries management, fin trade reduction and increasing trade restrictions under CITES, the future for blue sharks looks blue indeed.

Blue sharks dominate the shark fin trade, and landings worldwide have nearly tripled since 2000. Without global cooperation, the lack of management for blue sharks and extensive targeting by fisheries place them at great risk of extinction.

An estimated 20 million blue sharks are killed every year and enter the shark fin trade.

Despite huge catches, this species is unmanaged by the world’s RFMOs.

GSC_Protections_for_Threatened_Migratory_Sharks

IUCN status

The blue shark is considered Near Threatened globally and Critically Endangered in the Mediterranean.

Population threats

The species is caught in extensive, targeted fisheries on the high seas and is bycatch in other pelagic fisheries throughout its range. Blue sharks’ proportion of all shark landings tripled from 1998 to 2011-from 4 to 14 percent. The world’s most traded shark-valued for its fins in Asia and meat in Europe.

A 2006 study of the hong Kong fin trade by Clarke et al, provided the first fishery-independent estimate of the scale of shark catches worldwide. Their results indicate that shark biomass in the fin trade is three to four times higher than shark catch figures reported in the only global data base. Comparison of their estimates to approximated stock assessment for blue sharks, the most commonly traded species, blue shark, suggests that current trade volumes at or possibly exceeding the maximum sustainable yield levels at the time.

Blue shark Ciccone
What Sharks are Protected Under CITES

Management gaps

There are no fisheries management measures, or international trade regulations for blue sharks that extend throughout their range. Until globally applicable, enforceable measures are introduced to prevent overexploitation populations of this highly migratory species will continue to decline.

None of the major RFMOs has adopted catch or bycatch limits for this species. Scientists with the International Commission for the Conservation of Atlantic Tunas have repeatedly recommended capping Atlantic blue shark catches, particularly in the South Atlantic, where it is at higher risk, but no action has been taken.

Despite its status as the most-caught shark, P. glauca is not listed under CITES. The 2007 “Review of Migratory Chondrichthyan Fishes” by the IUCN and CMS noted:

There is no disagreement over the urgency of introducing management for this species; unfortunately no large-scale collaborative/regional management actions currently seem likely, other than those delivered through shark finning bans. The blue shark is certainly in urgent need of collaborative management by range States and through regional fisheries bodies, but appears not to be a high priority for action at the present time. A CMS Appendix II listing will help drive improvements in national and regional management that are required if this species is to be managed sustainably.

  • Nicholas K. Dulvy et al., “Extinction Risk and Conservation of the World’s Sharks and Rays,” eLife 3 (2014): e00590, http://dx.doi.org/10.7554/eLife.00590.

    • Blue sharks were proposed to be listed under CITES Appendix II in 2017 but that proposal failed. Since that time the world has lost millions more blue sharks and the need to protect them in 2022 is even more urgent.

    Support

    SOURCES

    1. Shelley Clarke et al., “Global Estimates of Shark Catches Using Trade Records From Commercial Markets,” Ecology Letters 9 (2006): 1115-26, https://www.iccs.org.uk/wp-content/papers/Clarke2006EcologyLetters.pdf.
    2. NOAA, “Update Assessment to SEDAR 21”; National Oceanic and Atmospheric Administration, “SEDAR 21 Stock Assessment Report: HMS Dusky Shark” (August 2011), http://sedarweb.org/docs/sar/Dusky_SAR.pdf.
    3. Shark Specialist Group of the IUCN Species Survival Commission, “Review of Migratory Chondrichthyan Fishes” (2007), https://portals.iucn.org/library/sites/library/files/documents/2007-042.pdf.
    4. Hideki Nakano and John D. Stevens, “The Biology and Ecology of the Blue Shark, Prionace glauca,” in Sharks of the Open Ocean: Biology, Fisheries and Conservation (2009), http://onlinelibrary.wiley.com/book/10.1002/9781444302516; Jiangfeng Zhu et al., “Reproductive Biology of Female Blue Shark Prionace glauca in the Southeastern Pacific Ocean,” Environmental Biology of Fishes 91 (2011): 95-102, https://link.springer.com/article/10.1007/s10641-010-9763-1.
    5. John Stevens, International Union for Conservation of Nature, “The IUCN Red List of Threatened Species: Prionace glauca,” accessed March 23, 2017, http://dx.doi.org/10.2305/IUCN.UK.2009-2.RLTS.T39381A10222811.en.
    6. Alexandre Aires-da-Silva and Vincent Gallucci, “Demographic and Risk Analyses Applied to Management and Conservation of the Blue Shark (Prionace glauca) in the North Atlantic Ocean,” Marine and Freshwater Research 58 (2008): 570-80, http://www.publish.csiro.au/mf/MF06156.
    7. Julia Baum and Wade Blanchard, “Inferring Shark Population Trends From Generalized Linear Mixed Models of Pelagic Longline Catch and Effort Data,” Fisheries Research 102 (2010): 229-39, http://www.sciencedirect.com/science/article/pii/S0165783609003087.
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    9. Steven E. Campana et al., “Effects of Recreational and Commercial Fishing on Blue Sharks (Prionace glauca) in Atlantic Canada, With Inferences on the North Atlantic Population,” Canadian Journal of Fisheries and Aquatic Sciences 63 (2006): 670-82, http://dx.doi.org/10.1139/F05-251.
    10. Colin A. Simpfendorfer, Michelle R. Heupel, and Robert E. Hueter, “Estimation of Short-Term Centers of Activity From an Array of Omnidirectional Hydrophones, and Its Use in Studying Animal Movements,” Canadian Journal of Fisheries and Aquatic Sciences 59 (2002): 23-32, http://www.nrcresearchpress.com/doi/abs/10.1139/f01-191#.WX1SiYTyuM8.
    11. Stevens 2009, “IUCN: Prionace glauca.”
    12. Hampus Eriksson and Shelley Clarke, “Chinese Market Responses to Overexploitation of Sharks and Sea Cucumbers,” Biological Conservation 184 (2015): 163-73, http://www.sciencedirect.com/science/article/pii/S0006320715000397.
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    16. Francesco Ferretti et al., International Union for Conservation of Nature, “The IUCN Red List of Threatened Species: Squatina squatina,” accessed March 29, 2017, http://dx.doi.org/10.2305/IUCN.UK.2015-1.RLTS.T39332A48933059.en.
    17. International Council for the Exploration of the Sea, “Report of the Working Group on Elasmobranch Fishes (WGEF)” (2016), 20, http://www.ices.dk/sites/pub/Publication%20Reports/Expert%20Group%20Report/acom/2016/WGEF/01%20WGEF%20report%202016.pdf; International Union for Conservation of Nature, “Red List of Threatened Species: Squatina squatina”; Nicholas Dulvy, Yvonne Sadovy, and John D. Reynolds, “Extinction Vulnerability in Marine Populations,” Fish and Fisheries 4 (2003): 25-64, http://onlinelibrary.wiley.com/doi/10.1046/j.1467-2979.2003.00105.x/abstract.
    18. Nicholas K. Dulvy et al., “Extinction Risk and Conservation of the World’s Sharks and Rays,” eLife 3 (2014): e00590, http://dx.doi.org/10.7554/eLife.00590.

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