Global catches, exploitation rates, and rebuilding options for sharks

Boris Worm, Brendal Davis, Lisa Kettemer, Christine A. Ward-Paige, Demian Chapman, Michael R. Heithaus, Steven T. Kessel, Samuel H. Gruber

Research output: Contribution to journalArticle

268 Citations (Scopus)

Abstract

Adequate conservation and management of shark populations is becoming increasingly important on a global scale, especially because many species are exceptionally vulnerable to overfishing. Yet, reported catch statistics for sharks are incomplete, and mortality estimates have not been available for sharks as a group. Here, the global catch and mortality of sharks from reported and unreported landings, discards, and shark finning are being estimated at 1.44 million metric tons for the year 2000, and at only slightly less in 2010 (1.41 million tons). Based on an analysis of average shark weights, this translates into a total annual mortality estimate of about 100 million sharks in 2000, and about 97 million sharks in 2010, with a total range of possible values between 63 and 273 million sharks per year. Further, the exploitation rate for sharks as a group was calculated by dividing two independent mortality estimates by an estimate of total global biomass. As an alternative approach, exploitation rates for individual shark populations were compiled and averaged from stock assessments and other published sources. The resulting three independent estimates of the average exploitation rate ranged between 6.4% and 7.9% of sharks killed per year. This exceeds the average rebound rate for many shark populations, estimated from the life history information on 62 shark species (rebound rates averaged 4.9% per year), and explains the ongoing declines in most populations for which data exist. The consequences of these unsustainable catch and mortality rates for marine ecosystems could be substantial. Global total shark mortality, therefore, needs to be reduced drastically in order to rebuild depleted populations and restore marine ecosystems with functional top predators.

Original languageEnglish
Pages (from-to)194-204
Number of pages11
JournalMarine Policy
Volume40
Issue number1
DOIs
StatePublished - Jul 1 2013

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shark
sharks
exploitation
mortality
rate
Exploitation
Mortality
marine ecosystem
Group
conservation
statistics
fisheries statistics
catch statistics
management
stock assessment
overfishing
Values
Marine ecosystems
Rebound
life history

Keywords

  • Conservation
  • Ecosystem management
  • Fishing mortality
  • Shark finning
  • Sharks

ASJC Scopus subject areas

  • Aquatic Science
  • Economics and Econometrics
  • Environmental Science(all)
  • Law
  • Management, Monitoring, Policy and Law

Cite this

Worm, B., Davis, B., Kettemer, L., Ward-Paige, C. A., Chapman, D., Heithaus, M. R., ... Gruber, S. H. (2013). Global catches, exploitation rates, and rebuilding options for sharks. Marine Policy, 40(1), 194-204. https://doi.org/10.1016/j.marpol.2012.12.034

Global catches, exploitation rates, and rebuilding options for sharks. / Worm, Boris; Davis, Brendal; Kettemer, Lisa; Ward-Paige, Christine A.; Chapman, Demian; Heithaus, Michael R.; Kessel, Steven T.; Gruber, Samuel H.

In: Marine Policy, Vol. 40, No. 1, 01.07.2013, p. 194-204.

Research output: Contribution to journalArticle

Worm, B, Davis, B, Kettemer, L, Ward-Paige, CA, Chapman, D, Heithaus, MR, Kessel, ST & Gruber, SH 2013, 'Global catches, exploitation rates, and rebuilding options for sharks', Marine Policy, vol. 40, no. 1, pp. 194-204. https://doi.org/10.1016/j.marpol.2012.12.034
Worm B, Davis B, Kettemer L, Ward-Paige CA, Chapman D, Heithaus MR et al. Global catches, exploitation rates, and rebuilding options for sharks. Marine Policy. 2013 Jul 1;40(1):194-204. https://doi.org/10.1016/j.marpol.2012.12.034
Worm, Boris ; Davis, Brendal ; Kettemer, Lisa ; Ward-Paige, Christine A. ; Chapman, Demian ; Heithaus, Michael R. ; Kessel, Steven T. ; Gruber, Samuel H. / Global catches, exploitation rates, and rebuilding options for sharks. In: Marine Policy. 2013 ; Vol. 40, No. 1. pp. 194-204.
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