Dear MARMAM community, On behalf of all co-authors, I am pleased to share with you our new paper on optimising the functioning of stranding networks in Europe in ICES Journal of Marine Science: Petitguyot, M. A. C, Fariñas-Bermejo, A., Brownlow, A., Ahola, M. P., Álvarez Neches, E., Arbelo, M., Authier, M., Balsera Riesgo, R., Berrow, S., Bjørge, A., Brackmann, J., Brasseur, S., Carreira, G., Cervin, L., Claver, C., Covelo, P., Crespo-Picazo, J. L., Dabin, W., Dähne, M., Davison, N. J., Deaville, R., ten Doeschate, M. T. I., Domingo Álvarez, M., Escribano Cánovas, F., Evans, P. G. H., Fayos Martínez, M., Fernández, A., Fernández, R., Fernández-Maldonado, C., Freitas, L., Galatius, A., García de los Ríos, A., Garrido Sánchez, L., Geut, M. I. M., Gilles, A., Gozalbes Aparicio, P., Grilo, M., Haelters, J., Halldórsson, S. D., Hamm, T., Havermans, J., IJsseldijk, L. L., Jacinto, D., Jussi, M., Kamminga, P., Kåre Jensen, T., Kavanagh, A. S., Keijl, G., Leopold, M., López, A., Marçalo, A., Marques, N., Martínez Cedeira, J. A., Mikkelsen, B., Miodonski, J., Monasterio Iglesias, J. M., Montes Gómez, J. E., Neimanis, A., Neves, F., Pardal, S. I., Pawliczka, I., Peña Pascucci, I., Petersen, H. H., Plikshs, M., Puig-Lozano, R., Raga, J. A., Robalo, J. I., Roos, A., Ruiz Sancho, L., Saavedra, C., Sigurðsson, G. M., Simião; S., Solomando Marti, A., Stavenow Jerremalm, J., Stejskal, O., Survilienė, V., Thøstesen, C. B., van der Hiele, J., Varas, J., Verdaat, H., Verheul, D., Víkingsson, G. A., Villalón, J., Williams, R.S., Woodlock, J., and Pierce, G. J. 2025. European stranding networks as a tool for monitoring marine mammal populations (Part I): towards optimising the functioning of networks. ICES Journal of Marine Science, 82(11):1-27. The paper is open access and available online at: https://academic.oup.com/icesjms/article/82/11/fsaf194/8339597 Abstract: The study of stranded animals is a valuable aid to monitoring marine mammals globally. However, the utility of strandings data depends on their quality and representativeness, which is affected by various biological, physical, social and economic factors. An analysis of how stranding networks work could help understand limitations in the data collected and facilitate correcting for or even eliminating them. In 2021, the International Council for the Exploration of the Sea’s Working Group on Marine Mammal Ecology carried out an expert consultation using a questionnaire to provide insight into the contribution of European stranding networks as a monitoring tool in European countries with Northeast Atlantic and adjacent coasts (hence also including some networks operating along the Mediterranean coast). A key aim was to identify ways to improve data on mortality of marine mammals due to fishery bycatch. The present paper is the first of a two-part series based on the responses to the questionnaire by 45 organisations from 19 countries, and focuses on characterising the activities and capacities of the stranding networks surveyed, identifying differences within and between countries, highlighting strengths and weaknesses, and providing recommendations to enhance the value and credibility of the information collected. The second paper will focus on the information specifically related to mortality due to fishery bycatch. Stranding networks provide extensive spatio-temporal coverage of European coastlines, but their activities may be constrained by limited resources as well as limitations imposed by the stranding process. There is a need for better coordination and standardisation of the collection and analysis of data and samples and increased spatial coverage to fill gaps. To improve data quality, in particular to support assessment of impacts of threats such as bycatch, more necropsies and associated sample analysis are needed. It would also be advantageous to collect more information from less fresh animals, record search effort, and give greater attention to pinnipeds and non-marine mammal taxa. We also highlight the need to make information available and the potential value of a common database. Streamlining the reporting of results at the European level and providing systematic funding to stranding networks in accordance with their needs are necessary steps to optimise their role as a tool for the long-term monitoring of marine mammals and other marine megafauna in Europe. Best wishes, -- Marie Petitguyot & Andrea Fariñas-Bermejo Institute of Marine Research - Spanish National Research Council Instituto de Investigaciones Marinas - IIM-CSIC C/ Eduardo Cabello, 6 CP 36208 Vigo (Pontevedra) Spain