Analysis of the effects of Somali piracy on the European tuna purse seine fisheries of the Indian Ocean

  • Chassot E
  • Dewals P
  • Floch L
 et al. 
  • 20

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Abstract

The European purse seine fishery of the Indian Ocean (IO) has been particularly affected by Somali piracy in the recent years. Consequently, several vessels left the IO and the overall carrying capacity of the fleet decreased by 25% between 2005-2008 and 2009. To address security issues, fishing companies defined in 2008 a large exclusion zone off the Somali coast that represented more than 25% of the total catch of the fishery during 2001-2007. The exclusion zone resulted in some reallocation of the European fleet toward the eastern part of the North equatorial area during the typical season of FAD-fishing (June-November) in the Somali basin. The European purse seine fleet catches in the exclusion zone decreased from an average of 90,000 t during 2001-2007 to less than 50,000 t in 2008. This was mainly due to the decrease in fishing effort, as measured by space occupancy, set number, and searching time for the French component of the fishery. The effort and catch concomitantly increased in the eastward part of the North equatorial area. Overall, the catch of the French fleet in the whole North equatorial area decreased by 5.4% in 2008 relative to 2001-2007 but increased by more than 25% relative to 2007. Considering a subset of French vessels that occurred in the IO during 2001-2010 confirmed that the vessels were able to recoup most losses in adjacent areas. In 2009, military and private security intervention reduced risk from piracy and enabled European purse seiners to move back to the Somali basin. The fishing effort of the fleet re-increased in the exclusion zone and led to catch levels similar to 2002-2007 for the French fleet while the effort and catches strongly decreased in the eastern part of the North equatorial area. Some changes in species composition, i.e. an increasing proportion of skipjack and bigeye, and size structure of the catch, i.e. smaller fishes, were observed in 2008-2009 due to the changes in spatial distribution of the French fleet as well as the increasing tendency to fish on log-associated schools. The current logistical constraints imposed on the French purse seiners, i.e. operating in pairs and fishing alternatively combined with the decrease in the number of vessels in the IO seems to have modified their fishing strategy by reducing their ability to explore large spatial areas and track free swimming schools. The increase in fishing on log-associated schools might have strong effects on the yield-per-recruit expected from the fishery as well as levels of bycatch that have not been monitored by EU observers since summer 2009.

Author-supplied keywords

  • Somali piracy
  • effort
  • fisheries
  • purse seine
  • tropical tuna

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Authors

  • E. Chassot

  • P. Dewals

  • L. Floch

  • V. Lucas

  • M. Morales-Vargas

  • D. Kaplan

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