Study on advancing fisheries assessment and management advice in the Mediterranean by aligning biological and management units of priority species MED_UNITs: final report

Stock identification provides a basis for understanding population dynamics and makes the stock assessment process more robust, thereby developing fisheries management strategies. Multiannual Management Plans under the Common Fishery Policy (EU Reg. 1380/2013) are tools for managing shared stocks in the long term and thus this requires improving our knowledge on biological stock units and fishery management units. Methods for delineating stocks advanced considerably in recent years and include genetic techniques, otolith shape and chemistry, acoustic telemetry, tagging, demographic analysis and meristic data. The integration of multiple techniques that operate over different temporal and spatial scales makes it possible to overcome many of the limitations of single technique approaches and strengthens the inference available from stock structure studies (Cadrin et al., 2013). The identification of fishing grounds is an essential information to delineate the fishing footprints on the fish and shellfish stocks. To identify fishing grounds different methods are available, based on Automatic Identification System (AIS) and Vessel Monitoring System (VMS). Linking information on stock boundaries with the one on the localization of the fishing grounds is a key step for the identification of spatial units for fishery management. The overall objective of the MED_UNITs project is to identify and match biological and management stock units of several important demersal species in the Mediterranean: European hake (Merluccius merluccius), red mullet (Mullus barbatus), deep water rose shrimp (Parapenaeus longirostris), giant red shrimp (Aristaeomorpha foliacea), blue and red shrimp (Aristeus antennatus) and Norway lobster (Nephrops norvegicus). The study covers the Geographical Sub-Areas (GSAs) 1-27 (Mediterranean Sea). The project structure consists of 5 Work-Packages (WPs) and 16 Tasks.WP0-Project management and coordination; WP1-Population genetics and phylogeographic studies for identification of biological units of priority species; WP-2 Otolith shape and microchemistry analyses; WP3-Delineate fishing grounds and stock assessment; WP4-Synthesis and proposals. The analyses undertaken in WP1 and WP2 delineate the population units from a biological perspective. WP3 defines the fisheries footprints not necessarily within the boundaries of the current GSAs. The integration of this information takes place in WP4, supported by the explanatory role of ecological/environmental profiles at spatial scale. Overall, this approach is expected to advance fisheries assessment and improve the management advice, reducing the bias associated with the assumption of a given stock unit, when instead multiple stocks are assessed as a single unit or only a portion of a stock is assessed as a closed unit.