Biodiversity and Conservation

, Volume 25, Issue 9, pp 1637–1659 | Cite as

Consequences of fishing moratoria on catch and bycatch: the case of tropical tuna purse-seiners and whale and whale shark associated sets

  • Lauriane EscalleEmail author
  • Daniel Gaertner
  • Pierre Chavance
  • Alicia Delgado de Molina
  • Javier Ariz
  • Bastien Merigot
Original Paper


Time–area regulations have been introduced to manage stocks of tropical tuna, given the increased use of drifting fish aggregation devices (FADs). However, the consequences in terms of changes in fishing strategies and effort reallocation may not always be as expected. For instance, in the eastern Pacific Ocean, previous studies have highlighted that the increase use of FAD-fishing following the demand for tuna caught without dolphin mortality has raised concerns about the bycatch and the capture of juvenile tuna. In the tropical eastern Atlantic and western Indian Oceans, this study aimed to (1) assess, using before–after analysis, the consequences of previous time–area regulations on FAD sets on the fishing effort allocated to megafauna associated sets, and (2) evaluate through Monte Carlo simulations the potential effect of new regulations banning whale or/and whale shark associated sets. Firstly, we showed that previous time–area regulations, which were mainly implemented during seasons with few whale and whale shark associated sets, generally had thus little effect on the number of megafauna associated sets. Secondly, some simulations, particularly when both whale and whale shark associated sets were banned, predicted consequences of changes in fishing strategy. Indeed, these types of ban could lead to an increase in the number of FAD and free school sets but no change in the tuna catch, as well as a slight decrease in bycatch. These results indicate that an ecosystem approach to fisheries, by taking into account megafauna associated sets and bycatch, should thus be adopted when implementing management or conservation measures.


Before–after analysis Time–area regulation Monte Carlo simulation Marine megafauna Purse-seine fishery 



We thank two anonymous Reviewers for their constructive comments on an earlier version of the manuscript. The authors are grateful to the skippers and fishing companies involved in the logbook data collection, which is supported by the French and Spanish National Fisheries Administrations and research institutes (IRD/IEO). We should also like to thank the teams of the “Observatoire Thonier” (IRD) and the “Centro Costero de Canarias” (IEO) for providing logbook data. L. Escalle is funded by a PhD grant from the University of Montpellier. T. Tebby has provided the English language editing for this paper.


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Copyright information

© Springer Science+Business Media Dordrecht 2016

Authors and Affiliations

  • Lauriane Escalle
    • 1
    • 2
    Email author
  • Daniel Gaertner
    • 2
  • Pierre Chavance
    • 2
  • Alicia Delgado de Molina
    • 3
  • Javier Ariz
    • 3
  • Bastien Merigot
    • 1
  1. 1.UMR MARBEC (IRD, Ifremer, Univ. Montpellier, CNRS)Université MontpellierSèteFrance
  2. 2.UMR MARBEC (IRD, Ifremer, Univ. Montpellier, CNRS)Institut de Recherche pour le DéveloppementSèteFrance
  3. 3.Instituto Español de OceanografíaS/C TenerifeSpain

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