Commission Decision of 25 February 2016 setting up a Scientific, Technical and Economic Committee for Fisheries, C(2016) 1084, OJ C 74, 26.2.2016, p. 4–10. The Commission may consult the group on any matter relating to marine and fisheries biology, fishing gear technology, fisheries economics, fisheries governance, ecosystem effects of fisheries, aquaculture or similar disciplines. This report is the third expert working group (EWG) report dealing with methods for developing the fishing effort regime for demersal fisheries in western Mediterranean Sea, after EWG 18-09 and 18-13. The group was requested to select the most appropriate model(s) to carry out a mixed-fisheries advice for the western Mediterranean demersal fisheries, and to analyse the ability of the model(s) to be compatible with the latest single-stock scientific advice provided for western Mediterranean demersal stocks Finally, the group was requested to discuss and suggest possible mixed-fisheries scenarios and type of results for future developments. The EWG reviewed 8 different models, of different complexity levels and covering different GSAs and EMUs. For EMU2 (East side of Western Med, which mainly includes fisheries from one single Member State), 3 models were presented, which are fully parameterised and operational. The situation is more challenging in EMU1 (West side of Western Med, which covers fisheries from two Member States), where five models were presented but none of them is directly operational at the scale of the EMU. Progresses were reached during the EWG, but further intersessional work, involving scientists from the two Member States, is necessary before reaching the desired level of completion for the evaluation of management scenarios. During the EWG, all models presented were updated to the most recent information available. Where possible, short-term forecasts were run, assuming a reduction in fishing effort in 2019 equivalent to the reduction necessary to achieve the target F (Fmsy, proxy F01). For all models, the aggregated results of the short term forecast were largely similar between the single-stock and the mixed-fisheries models. Then most models were able to run the basic MAP scenario of a gradual reduction of fishing effort between 2020 and 2024. Several alternative runs and model capabilities were discussed. Finally, the EWG discussed a number of remaining issues and gaps that are important in relation to the scientific support to the MAP, and agreed on some future work.