SEAwise Report on consistent targets and limits for indicators in an ecosystem context
Creators: name: Kempf, Alexander
name: Taylor, Marc
name: Kühn, Bernhard
name: Letschert, Jonas
name: Brown, Elliot John
name: Trijoulet, Vanessa
name: Vinther, Morten
name: Hernvann, Pierre-Yves
name: Girardin, Raphaël
name: Savina-Rolland, Marie
name: Lehuta, Sigrid
name: Halouani, Ghassen
name: Robert, Marianne
name: Woillez, Mathieu
name: Mahevas, Stéphanie
name: Travers-Trolet, Morgane
name: Andres, Marga
name: Garcia, Dorleta
name: Ibaibarriaga, Leire
name: Sánchez-Maroño, Sonia
name: Diaz, Amaia Astarloa
name: Altuna-Etxabe, Miren
name: Mencia, A.
name: Batts, Luke
name: Reid, David
name: Bitetto, Isabella
name: Teresa Spedicato, Maria
name: Romagnonia, Giovanni
name: Lembo, Guiseppe
name: Zupa, Walter
name: Giannoulaki, Marianna
name: Sgardeli, Vasiliki
name: Papantoniou, Georgia
name: Tsoukali, Stavroula
name: Liontakis, Angelos
name: Vassilopoulou, Celia
name: Millar, Sarah
name: Depestele, J. (Jochen)
name: van Hoey, Gert
name: Sys, Klaas
name: van de Wolfshaar, Karen
name: Piet, Gerjan
name: Hamon, Katell
name: Kraan, Marloes
name: Smout, Sophie
name: Ransijn, Janneke
name: Thorpe, Robert
name: Lynam, Chris
name: Bluemel, Joanna
name: Voss, Rüdiger
name: Ojaveer, Henn
name: Hommik, Kristiina
name: Melia, Paco
name: Gascuel, Didier
name: Potier, Mikaela
name: Ustups, Didzis
name: Plikshs, Maris
name: Heath, Mike
name: Poos, J.J. (Jan Jaap)
name: Binch, Logan
name: Rindorf, Anna
Publisher: name: Technical University of Denmark
Year: 2025
Subjects: classificationCode: 410102
subject: Ecological impacts of climate change and ecological adaptation
classificationCode: 410103
subject: Human impacts of climate change and human adaptation
classificationCode: 410402
subject: Environmental assessment and monitoring
classificationCode: 410401
subject: Conservation and biodiversity
classificationCode: 410404
subject: Environmental management
classificationCode: 410406
subject: Natural resource management

description: 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. This SEAwise report describes a wide variety of model types (from bio-economic to full ecosystem models) to case studies across the Northeast Atlantic and Mediterranean. The aim was to identify the main trade-offs between the objectives from the CFP and MSFD as well as global indicators like CO<sub>2 </sub>footprint for each case study region. The models included climate change scenarios to evaluate the impact of climate change on indicators and trade-offs between them. In addition, knowledge on bycatch, benthic impact (e.g., indicator based on Relative Benthic State (RBS)) and food webs (i.e. also taking into account the role of forage fish) was included. Information on the impact of marine spatial planning was included in some case studies to evaluate potential impacts of currently implemented and planned spatial management options on indicators and trade-offs. The work was based on new and improved models from previous SEAwise tasks.The effect of each of five scenarios aligned with the maximum sustainable yield concept (e.g. strict MSY approach with enforced landing obligation, Pretty Good Yield (PGY), current single species management) on ecological objectives and fishing opportunities were investigated across the Mediterranean and Northeast Atlantic. For all management scenarios, the effects of climate change according to two climate scenarios were also investigated: RCP4.5 (Intermediate Representative Concentration Pathway (RCP), where climate policies limit and achieve stabilization of greenhouse gas concentrations to 4.5 W m-2 by 2100) and RCP8.5 (Worst case Representative Concentration Pathway (RCP), where high emissions of greenhouse gases continue in the absence of climate change policies) trajectories for environmental variables were tested. In addition, the effect of selected spatial closures was investigated. Model predictions are uncertain and can be biased due to structural uncertainties and assumptions behind modelling approaches and data availability. The results revealed large uncertainty in many cases and the results should therefore be interpreted in the context of the models used and assumptions made.Technical interactions among fleets operating in the demersal mixed fisheries in the <b>Eastern Ionian Sea</b> were very strong and MSY related targets could not be achieved simultaneously for all stocks. The deep water rose shrimp stock is currently underutilized, but an increase in harvest of this could lead to increased depletion of the most exploited stock hake. A strict management focus to protect European hake will apply a greater reduction in the small-scale fleet than the large-scale fleet and could benefit European hake. Indicators related to good environmental status (GES) and global indicators like CO<sub>2</sub> footprint also benefited from the low fishing effort in this scenario but it provided the lowest landings, lower gross value added and employment compared to the status-quo scenario. Management trying to balance the exploitation of the different resources and objectives in an PGY approach could be an alternative but would result in a higher bycatch of dolphins than in the strict MSY scenario. Climate change only had minor effects on overall model outcomes.Strong reductions in effort in the <b>Adriatic and western Ionian Sea</b> were needed to achieve the target fishing mortalities for the most limiting stocks under a strict MSY approach. This reduction had negative consequences for social benefits like employment and a PGY approach led to similar results. Among the scenarios, only the strict MSY scenario combined with areas closed to fishing came near the potential GES threshold for benthic habitats. The spatial management scenarios only had minor effects on indicators and associated trade-offs. The ecosystem model applied for this region predicted climate change effects that could be buffered to some extent by the strict MSY and PGY scenarios. Reductions in biomass of most functional groups were seen in the model predictions.Gross value added, kg CO<sub>2</sub>/kg landed, bycatch of dolphins and the proportion of stocks with &gt;=5% probability of falling below the limit biomass all benefited when aiming for one of the more restrictive management scenarios in the <b>Bay of Biscay</b>. However, none of the scenarios led to all stocks having a less than 5% probability to fall below the limit biomass and all led to lower wages, lower landings and hence food security. The predicted forage fish biomass was above the potential threshold of one third of the maximum in all scenarios. It was unclear if bycatch limits for common dolphins were reached under the scenarios as only parts of the fisheries and regions were considered in the model. The bycatch limits of Balearic Shearwaters exceeded the threshold in all scenarios. Overall, conservation objectives were most likely to be achieved under a strict MSY scenario. A case-specific scenario aiming for more stability in fishing effort provided higher landings and socio-economic benefits and led to only minor differences in GES and global indicators. Climate change and spatial closures had minor effects on results, but this may be a consequence of the limited climate effects considered and how the approach to simulating spatial closure effects.Strict MSY management in the <b>Celtic Sea</b> led to a clear improvement in many MSFD and global indicators and a more sustainable exploitation of cod and whiting. The impact on benthic habitats reached the proposed definition of GES in all scenarios tested. These benefits were accompanied by lower landings and employment compared to the status-quo scenario. PGY management did not alleviate this. There was a potential positive effect of climate change on landings and CO<sub>2 </sub>footprint due to positive effects on hake and megrim in the fleet-based model. In contrast, the two ecosystem models applied predicted that climate change will lead to declining primary production and rising temperatures will decrease efficiency of energy transfer up the food web, resulting in disproportionate declines in higher trophic levels. These results highlight the structural uncertainties in predicting impacts of climate change.Strict MSY management of the <b>North Sea </b>fisheries led to a clear improvement in many GES and global indicators. There was no management scenario that was perfect in all regards. Management based on PGY balanced landings and economic losses, but this came at a cost of higher CO<sub>2</sub> emissions, more bycatch of harbour porpoise, less large fish and higher benthic impact (though still within potential thresholds for the whole region). Sustainable management of stocks was still possible under climate change, but productivity declines of cod and saithe will drive declines of indicators of large fish with a subsequent need to adapt the thresholds. The ecosystem models predicted a negative impact of climate change on primary production and a decreasing efficiency of energy transfer up the food web. A multi species model focusing on predation demonstrated that the management applied for the demersal stocks will affect stock size and yield of the forage fish stocks. However, the harvest strategies for forage fish currently in place were robust to changes in climate and management options for the demersal predators and the biomass was sustained above one third of the maximum biomass threshold suggested as the limit for impacting seabirds. The results did not include stochasticity and hence the limit can potentially be reached in some years (but not on average). A spatially disaggregated ecosystem model showed no strong overall effect on fish biomass and GES indicators while catch was strongly affected by the displacement of fishing effort. Indicators did not always in the desired direction, highlighting that effects of effort displacement have to be taken into account.Climate change was predicted to have a severe impact on the stocks of <b>western Baltic</b> cod and herring, challenging for sustainable management of the stock and making it difficult to achieve EBFM related goals like keeping the herring stock above one third of the maximum biomass. The current low fishing mortalities well below F<sub>MSY </sub>(closer to maximum economic yield) were the best option, except for landings and employment. A sustainable exploitation of stocks will be a serious challenge under predicted climate change impacts.Read more about the SEAwise project at https://seawiseproject.org/