Adaptation of the Western
Baltic Coastal Fishery to
Climate Change
RESULTS
2023
> Food for growth - bioenergetic modeling helps understanding climatic effects on cod growth
Funk, S., Funk, N., Herrmann, J. P., Hinrichsen, H. H., Krumme, U., Möllmann, C., & Temming, A. (2023). Tracing growth patterns in cod (Gadus morhua L.) using bioenergetic modelling. Ecology and Evolution, 13(11), e10751| > original article
Western Baltic cod is an ideal case study for bioenergetic modelling because of recently gained in-situ process knowledge on spatial distribution and feeding behaviour based on highly resolved data on stomachs and fish distribution. Additionally, physiological processes such as gastric evacuation, consumption, net-conversion efficiency and metabolic rates have been well studied for cod in laboratory experiments. Our model reliably reproduced seasonal growth patterns observed in the field. Importantly, our bioenergetic model- ling approach implementing depth-use patterns and food intake allowed us to ex- plain the potentially detrimental effect summer heat periods have on the growth of Western Baltic cod that likely will increasingly occur in the future. Hence, our model simulations highlighted a potential mechanism on how warming due to climate change affects the growth of a key species that may apply for similar environments elsewhere.
> Food web models scrutinized
Keramidas, I., Dimarchopoulou, D., Ofir, E., Scotti, M., Tsikliras, A.C. & Gal, G. (2023). Ecotrophic perspective in fisheries management: a review of Ecopath with Ecosim models in European marine ecosystems. Frontiers in Marine Science 10, 1182921. https://doi.org/10.3389/fmars.2023.1182921 | > original article
The aim of this work was to present food web models developed using the Ecopath with Ecosim (EwE) software tool to describe the structure and functioning of different marine ecosystems in Europe (Eastern, Central and Western Mediterranean, Black Sea, Bay of Biscay, Celtic Sea and Iberian coast, Baltic Sea, North Sea, English Channel, Irish Sea and Western Scotia Sea, Norwegian Sea and Barents Sea). A total of 195 Ecopath models were reviewed based on 168 scientific publications containing original, updated and modified versions. Seventy models included temporal Ecosim simulations, while 28 models implemented the spatio-temporal dynamics of Ecospace. Most of the models and releases were related to the western Mediterranean Sea, followed by the English Channel, Irish Sea and West Scotia Sea sub-regions. In the Mediterranean Sea, most models and publications were for the western region, followed by the central and eastern regions; similar trends were observed in previous literature reviews. Most modelling focused on ecosystem functioning and fisheries-related hypotheses, while some models examined the effects of climate change, alien species abundance, aquaculture, chemical pollution, infrastructure and energy production.
2022
> Ecosystem-based management as beacon of hope
Scotti, M., Opitz, S., MacNeil, L., Kreutle, A., Pusch, C., & Froese, R. (2022). Ecosystem-based fisheries management increases catch and carbon sequestration through recovery of exploited stocks: the western Baltic Sea case study. Frontiers in Marine Science 9, 879998. https://doi.org/10.3389/fmars.2022.879998| > original article
This study presents the first mass-balanced ecosystem model focussing on the western Baltic Sea. The model provides a coherent assessment of trophic guilds in the western Baltic Sea, as required by European legislation to assess whether European seas are in good environmental status. The results show, for example, that the strong fishing pressure in the western Baltic Sea has forced top predators such as harbour porpoises and cod to meet their food requirements by switching from forage fish to other prey or finding food outside the model area. Management as before would not lead to the long-term recovery of fish stocks. In contrast, the ecosystem-based management scenario would allow the recovery of harbour porpoises, forage fish and cod, with herring and cod catches increasing. The ecosystem-based management scenario promotes ecosystem resilience to eutrophication and ocean warming and increases carbon sequestration more than threefold compared to the "business as usual" scenario by replenishing commercial stocks.
> Defining transdisziplinarity
Grünhagen, C., Schwermer, H., Wagner-Ahlfs, C., Voss, R., Gross, F., & Riekhof, M.-C. (2023). The multifaceted picture of transdisciplinarity in marine research. In S., Gomez Mestres & V., Köpsel, Transdisciplinary Marine Research – Bridging Science and Society (Volume 1). Abingdon: Routledge. | > original article
Transdisciplinary research is often compared with disciplinary, multi- and interdisciplinary research. While disciplinary research comprises only one discipline, multi- and interdisciplinary research include several disciplines. The difference to interdisciplinary research is that all disciplines work together in order to achieve the objectives defined within the framework of a specific project. Transdisciplinary research also involves stakeholders from different backgrounds
> Complex processes regulate herring recruitment in the Western Baltic Sea
Moyano, M., Illing, B., Akimova, A., Alter, K., Bartolino, V., Börner, G., Clemmesen, C., Finke, A., Gröhsler, T., Kotterba, P., Livdane, L., Mittermayer, F., Moll, D., von Nordheim, L., Peck, M.A., Schaber, M., & Polte, P. (2022). Caught in the middle: bottom-up and top-down processes impacting recruitment in a small pelagic fish. Reviews in Fish Biology and Fisheries 33, p. 55–84. https://doi.org/10.1007/s11160-022-09739-2 | > original article
Using the example of the spring spawning herring (Clupea harengus) in the western Baltic Sea, a holistic approach is tested to illustrate the high complexity of recruitment factors (and their interactions). Since the early 2000s, low recruitment has led to intensive research on this stock. Our literature synthesis suggests that the main drivers are decrease in and degradation of spawning habitats (mainly due to eutrophication and coastal changes) and warming, which indirectly lead to changes in spawning phenology, prey abundance and predation pressure. Other factors are the increasing intensity of extreme climate events and new predators in the system. Further, we propose specific research topics to fill remaining knowledge gaps in these areas and priorities to support sustainable management of the stock. As the Baltic Sea is strongly affected by warming, eutrophication and changes in precipitation, the herring could be an indicator species of possible impacts of changing environmental factors on the recruitment of small pelagic fish in other coastal areas of the world.
> Common Conceptual Mapping - new methods for participatory approaches
Afonso, F., Belgrano, A., Clay, P., DePiper, G., Garcia de Vinusea, A., Kellner, J., Kenny, A., Jørgensen, L. L., Lucey, S., Marcone, O., Melkert, R., Mikkelsen, N., Olsen, E., Raminez Monsalve, P., Schwermer, H., Seixas, S., Silva, A., Tam, J., Tyrell, A., Valman, M. (2022). Joint ICES/EUROMARINE Workshop on Common Conceptual Mapping. Methodologies (WKCCMM; Outputs from 2021 meeting). ICES Scientific Reports. 4:19. 41 pp. http://doi.org/10.17895/ices.pub.10095 | > original article
The ICES/EUROMARINE Workshop on Common Conceptual Mapping focused on developing a common understanding of conceptual mapping methods, their main uses and limitations, and procedures for effective conceptual modelling with stakeholders for a variety of applications (e.g. food web development, socio-ecological modelling, scoping exercises, rapid/first management actions and/or impact assessments). The discussion included the presentation and discussion of a range of conceptual modelling approaches and contexts through the examination of case studies. These case studies led to a number of recommendations, including the development of a workflow for the IEA, as well as more general guidance and best practice advice for using conceptual modelling approaches with stakeholders.
2021
> A question of perspective
Schwermer, H., Aminpour, P., Reza, C., Funk, S., Möllmann, C. & Gray, S. (2021). Modeling and understanding social–ecological knowledge diversity. Conservation Science and Practice 3, e396. https://doi.org/10.1111/csp2.396 | > original article
In this study, we conducted 33 interviews with stakeholders such as representatives of the fishing industry and NGOs. Stakeholder knowledge was analysed and modelled using western Baltic Sea fisheries as case study. This knowledge plays a key role in the sustainable management of fish stocks and their fisheries. The results show that the perceptions of user and interest groups, such as fishermen, vary greatly in some cases. Uncovering precisely these differences, but also similarities, could help to uncover conflicts and reduce them in a targeted manner through participatory approaches.
> Not all cod are the same
Schwermer, H., Blöcker, A., Möllmann, C. & Döring, M. (2021): The ‘Cod-Multiple’: Modes of Existence of Fish, Science and People. Sustainability 13, 12229. https://doi.org/10.3390/su132112229 | > original article
Our qualitative analysis of interviews with experts from commercial fisheries, NGOs and fisheries administration, among others, reveals a wide diversity of knowledge types around western Baltic cod, its fisheries and management. The study points to the need to change fisheries management in a more social and participatory way. To promote sustainable management of natural resources, it is important not only to integrate "more" knowledge (knowledge sharing), but rather to create opportunities in which, for example, fishermen are involved in decision-making processes at the local level (co-management). The reason for this is not least to create trust between and within interest groups, but also to increase the acceptance of management decisions.
> "Tipping Point" realized in cod fishery in the Western Baltic Sea
Möllmann, C., Cormon, X., Funk, S., Otto, SA, Schmidt, JO, Schwermer, H., Sguotti, C., Voss, R. & Quaas, M. (2021). Tipping point realized in cod fishery. Scientific Reports 11, 14259. https://doi.org/10.1038/s41598-021-93843-z | > original article
Our analysis of the temporal dynamics of the cod in the Western Baltic Sea shows that the stock and the fishery have exceeded a "tipping point" that was caused by unsustainable fishing and is now being stabilized by the warming of the Baltic Sea caused by climate change. A conclusion from the analysis is that a rapid recovery of the stock is unlikely. Only with low fishing pressure can the parent population be built up again over a longer period of time, so that the probability of successful offspring is increased again.
> Effects of mild winters on herring offspring in the Western Baltic Sea
Polte, P., Gröhsler, T., Kotterba, P., von Nordheim, L., Moll, D., Santos, J., Rodriguez-Tress, P., Zablotski, J. & Zimmermann, C. (2021) Reduced reproductive success of Western Baltic herring ( Clupea harengus ) as a response to warming winters. Frontiers in Marine Science , 8, 10. https://doi.org/10.3389/fmars.2021.589242 | > original article
On the basis of a field study to assess factors that determine the spawning time of herring, a temperature threshold of 4 °C was identified, which defines the beginning of the annual spawning season. Our time series analysis of the reproductive success of herring in the Western Baltic Sea shows that relative to the temperature threshold, late, mild winters and the resulting seasonally earlier hatching time of the herring larvae have a negative effect on the reproductive success.