Report of the Workshop on Sea Trout 2 (WKTRUTTA2)

The second Workshop on Sea Trout (WKTRUTTA2) met at the ICES Headquarters, Co-penhagen, Denmark, 2–5 February 2016, under the chairmanship of Ted Potter, UK, and Johan Höjesjö, Sweden. The meeting was attended by 22 participants from seven coun-tries. The principal aims of the Workshop were to review different approaches for mod-elling sea trout (anadromous Salmo trutta) populations and assessing the status of stocks. The group was also asked to provide a review of currently used monitoring methods, an initiation of the work to develop Biological Reference Points (BRPs) or alternative meth-ods to assess the status of sea trout populations, and recommendations for how this work could be taken forward.The Workshop considered the management requirements for modelling sea trout popula-tions and the application of BRPs. These fell into two groups, the first relating to as-sessing stock abundance and diversity against reference levels and the second to investigating the impacts of natural and anthropogenic factors, including fisheries, on stocks.Sea trout frequently coexist with salmon and are caught in the same fisheries in coastal waters, estuaries and rivers, but they have often taken second place in management, and in some countries little attention has been paid to the monitoring and assessment of sea trout stocks and fisheries. As a result, the quality of catch and fishing effort statistics is very variable. Juvenile monitoring is conducted in all countries, in many cases related to the EU Water Framework Directive, although sampling programmes are not always well structured, systematic or consistent over time. Some countries have developed extensive networks of counters, usually targeted at monitoring salmon, and in some cases these also provide good data on runs of sea trout. The Workshop compiled a summary of mon-itored/index stocks for which detailed data are obtained, but there are few such stocks and the aims of the programmes and the lengths of the resulting time series vary consid-erably.The Workshop assembled a preliminary table of sea trout rivers to support an eventual map. Stocks were graded on the proportion that was thought to be anadromous using a five-point scale, based on expert opinion, informed where possible by data on sea trout and salmon rod catches and/or samples taken by trapping or electrofishing. The Work-shop recommended that the development of these databases should be completed by a follow-on expert group (see below).