Methodologies for Mediterranean stock assessments (STECF-25-01)

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 addresses issues identified by past stock assessment working groups related to two key phases of the stock assessment process. The first one covers data preparation and processing, which includes extracting data from the Mediterranean and Black Sea database, handling missing data, applying raising procedures, selecting natural mortality rates, and slicing length frequency distributions. The second is to standardize several stock assessment routines such as diagnostic plots, short-term forecast and the calculation of partial fishing mortality by gear. The terms of reference highlighted the need to streamline both the data processing routines and the stock assessment routines. To this purpose, several new scripts were developed with corresponding methodology and guidelines, which are described in this report. The new routines and methods should be used in the following stock assessment EWGs.