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Project M.3.b - Spatial and temporal closures and the tradeoff between bycatch and target catches

01 Jan 2020 - 31 Dec 2021

Program(s) in charge: Ecosystem & Bycatch Program
Explore the effectiveness of different types of spatial and temporal closures in reducing bycatch with the lowest losses in target catch
  • A major impediment to ensuring fisheries sustainability is the impact of fishing practices on non–targeted species, particularly bycatch of marine megafauna
  • Many bycatch mitigation measures have been developed to reduce the impact on bycatch species. However, most of the measures have been designed to reduce bycatch of only one species or group of species
  • Spatial and temporal closures are another common management measure to reduce bycatch, although they have not been explored in detail in the region
  • A major concern about the efficacy of spatial and temporal closures is the potential for fishing effort to be redistributed rather than reduced. As a result, it creates a tradeoff between reduced fishing mortality inside protected areas or seasons, and a potential increase in surrounding waters or open seasons
  • However, the effectiveness of permanent or dynamic area closures at reducing multispecies bycatch is still an open question fur tuna purse seine fisheries in the EPO
Relevance for management
Reducing bycatch while maintaining target species catch would make the purse seine fishery more selective and cleaner. In addition, managers will be provided with the necessary information to start the conversation on different types of spatial and temporal closures that could be applied in the region, if needed
24 months
Workplan and status
  • Sep-Dec 2020: Data preparation and exploration; decide weights for key bycatch species and groups
  • Jan-Mar 2021: Run analysis and models
  • Apr-Jun 2021: Discussion of results and preparation of a manuscript for a peerreviewed journal
External collaborators
University of Washington, School of Aquatic and Fishery Sciences
  • A manuscript for a peer-review journal
  • Dissemination material for the Bycatch Working Group, likely in 2022
Updated date: 01 May 2022
Progress summary for the reporting period
  • Jan-Sept 21: Run regional analyses for the purse seine observer data, by set type.
  • Sept 21-Jan 22: Discuss results and write scientific manuscript.
Challenges and key lessons learnt
  • Static spatial and temporal closures seem less effective to reduce bycatch than dynamic closures, particularly for highly mobile species.
  • The degree of bycatch reduction achievable for a certain quantity of target catch is related to the correlation in space and time between target and bycatch species. If the correlation is high, it is harder to find an area to reduce bycatch without sacrificing catch of target species.
  • The use of dynamic ocean management might be difficult to implement and enforce on many occasions. Nevertheless, dynamic approaches will be increasingly valuable in a constantly changing environment and underscore the need for more responsive and flexible regulatory mechanisms.
A peer review publication and a presentation for BYC-11
Pons, M., J. T. Watson, D. Ovando, S. Andraka, S. Brodie, A. Domingo, M. Fitchett, R. Forselledo, M. Hall, E. L. Hazen, J. E. Jannot, M. Herrera, S. JimĂ©nez, D. M. Kaplan, S. Kerwath, J. Lopez, J. McVeigh, L. Pacheco, L. Rendon, K. Richerson, R. Sant ’Ana, R. Sharma, J. A. Smith, K. Somers and R. Hilborn (2022). "Trade-offs between bycatch and target catches in static versus dynamic fishery closures." Proceedings of the National Academy of Sciences 119(4): e2114508119.