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

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posted on 2024-02-07, 09:21 authored by Alexander Kempf, Marc Taylor, Bernhard Kühn, Elliot John BrownElliot John Brown, Vanessa TrijouletVanessa Trijoulet, Morten VintherMorten Vinther, Raphael Girardin, Marie Savina-Rolland, Sigrid Lehuta, Ghassen Halouani, Marianne Robert, Woillez, Mathieu, Stéphanie Mahevas, Morgane Travers, Marga Andres, Dorleta Garcia, Leire Ibaibarriaga, Sonia Sánchez-Maroño, Amaia Astarloa Diaz, Luke Batts, David Reid, Isabella Bitetto, Maria-Teresa Spedicato, Giovanni Romagnoni, M. Giannoulaki, Vasiliki Sgardeli, Stavroula Tsoukali, Angelos Liontakis, Celia Vassilopoulou, Sarah Millar, J. (Jochen) Depestele, Gert van Hoey, Gerjan Piet, Katell HamonKatell Hamon, Marloes KraanMarloes Kraan, Sophie Smout, Johanna Ransijn, Robert Thorpe, Chris Lynam, Joanna Bluemel, Rudi Voss, Henn Ojaveer, Kristiina Hommik, Paco Melia, Didier Gascuel, Mikaela Potier, Didzis Ustups, Maris Plikshs, Michael Heath, J.J. (Jan Jaap) Poos, Logan Binch, Anna RindorfAnna Rindorf

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 across 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 FMSY 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 (i.e. FMSY as upper limit with fisheries ending when the first stock reaches FMSY) 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 CO2 emission or ecosystem-based indicators like catch per km2. 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 FMSY point estimate when stocks are in a healthy state often outperformed the scenarios applying FMSY 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 km2 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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