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Reports Year : 2023

SEAwise Report on consistency of existing targets and limits for indicators in an ecosystem context

Alexander Kempf
Bernhard Kühn
  • Function : Author
Elliot Brown
  • Function : Author
Vanessa Trijoulet
Morten Vinther
  • Function : Author
Anna Rindorf
Marga Andres
  • Function : Author
Dorleta Garcia
  • Function : Author
Leire Ibaibarriaga
Sonia Sanchez‐maroño
Amaia Astarloa
  • Function : Author
Luke Batts
  • Function : Author
Isabella Bitetto
Maria Teresa Spedicato
Giovanni Romagnoni
  • Function : Author
Marianna Giannoulaki
  • Function : Author
Vasiliki Sgardeli
  • Function : Author
Stavroula Tsoukali
  • Function : Author
Angelos Liontakis
  • Function : Author
Celia Vassilopoulou
  • Function : Author
Sarah Miller
  • Function : Author
Jochen Depestele
  • Function : Author
Gert van Hoey
  • Function : Author
Gerjan Piet
  • Function : Author
Katell Hamon
  • Function : Author
  • PersonId : 875089
Marloes Kraan
Sophie Smout
Janneke Ransijn
  • Function : Author
Robert Thorpe
  • Function : Author
Chris Lynam
  • Function : Author
Joanna K. Bluemel
  • Function : Author
Rudi Voss
  • Function : Author
Henn Ojaveer
Kristiina Hommik
  • Function : Author
Paco Melià
Didzis Ustups
Maris Plikss
  • Function : Author
Mike Heath
  • Function : Author
Jan Jaap Poos
Logan Binch
  • Function : Author

Abstract

The SEAwise project works to deliver a fully operational tool that will allow fishers, managers, and policy makers to easily apply Ecosystem Based Fisheries Management (EBFM) in their fisheries. This SEAwise report investigates the consistency of existing targets and limits from the Common Fisheries Policy (CFP) and the Marine Strategy Framework Directive (MSFD). Trade-offs between different objectives (ecological, economic, social), targets and limits are highlighted. A wide range of model types (from bio-economic to full ecosystem models) has been applied to various case study areas accross the North East Atlantic and Mediterranean. Although model predictions are by nature uncertain, this study provides important information on likely inconsistencies between existing targets and limits and trade-offs expected under ecosystem- based fisheries management (EBFM). The scenarios investigated include the current range of management applied in terms of the Maximum Sustainable Yield (MSY) concept (i.e. strict MSY approach vs. Pretty Good Yield (PGY) approach allowing sustainable deviations from single species point estimates). The landing obligation is a key aspect of current fisheries management and was fully considered, in particular for mixed demersal fisheries.Maintaining current fishing effort without further management measures was the least sustainable option in nearly all cases studies. This approach led to increased risk of stocks falling below critical biomass limits. Although the fishing effort adaptions needed is highly case specific, this indicates that further management measures are likely to be needed to ensure a sustainable exploitation of all stocks.Scenarios applying a strict MSY approach in combination with the landing obligation as upper limit with fisheries ending when the first stock reaches in most case studies led to the lowest fishing effort. This had positive effects on MSFD related indicators such as bycatch of Protected, Endangered and Threatened (PET) species, benthic impact and the Large Fish Indicator as well as global indicators such as CO emission or ecosystem-based indicators like catch per . However, this scenario often led to the lowest catches from mixed demersal fisheries due to strong choke effects because fleets had to stop when their first quota was exhausted. This reduces social indicators such as food security, employment and wages. In terms of economic performance, the gains and loses were highly case specific. Scenarios applying the Pretty Good Yield concept and allowing sustainable deviations from the point estimate when stocks are in a healthy state often outperformed the scenarios applying as strict upper limit. Such scenarios, applying a more flexible interpretation of the MSY concept, led to reduced fishing effort compared to the status quo effort, but relaxed choke situations in mixed demersal fisheries to some extent leading to higher gross profits and in some case studies also to higher catches. Hence, they may constitute a compromise between the need to attain social as well as ecological objectives. Whether the associated effort levels lead to conflicts with MSFD objectives must be analysed when more internationally agreed thresholds become available for e.g., bycatch of PET species or benthic impact.The majority of case studies exceeded suggested thresholds for the global ecosystem indicators catch per km or primary production even under scenarios with high effort reductions. This can be explained to some extent by the fact that these indices are mainly driven by pelagic and industrial fisheries not always part of the models applied. Nevertheless, it indicates potential conflicts with such more holistic ecosystem indicators in their current form.Additional trade-offs in terms of yield were identified within the food web if e.g., demersal piscivorous predators feed on small pelagic fish and both groups are fished. Further, in case studies where small-scale fisheries (SSF) play an important role (e.g., Eastern Ionian Sea) additional trade-offs became apparent as different scenarios led to different ratios between revenues from small scale fisheries and revenues from large-scale fisheries. This adds another level of complexity when such aspects need to be taken more into account in future fisheries management under EBFM.The modelling assumed current selectivities and catchabilities will be maintained in the future. Especially trade-offs arising from fleets having to stop fishing when their first quota is exhausted or when e.g., a threshold for bycatch of PET species is reached may be resolved by improving selectivities via technical measures (e.g., closed areas or innovative gears) in the future. Deliverable 6.8 in month 36 will test such scenarios. Furthermore, the list of indicators and their targets and limits will be updated based on research within and outside SEAwise. Predictive capability of models will be enhanced by incorporating improved biological and economic sub-models in relation to environmental change. Climate change scenarios will be run and new harvest control rules (HCRs), proposed by SEAwise, will be tested. Finally, consistent targets and limits will be proposed for implementing EBFM.
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hal-04495754 , version 1 (10-04-2024)

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Alexander Kempf, Marc Taylor, Bernhard Kühn, Elliot Brown, Vanessa Trijoulet, et al.. SEAwise Report on consistency of existing targets and limits for indicators in an ecosystem context. Institut Agro - Rennes Angers; Technical University of Denmark. 2023, pp.245 P. ⟨hal-04495754⟩
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