ICES WKTRUTTA REPORT 2013 SCICOM STEERING GROUP ON ECOSYSTEM FUNCTIONS ICES CM 2013/SSGEF:15 REF. WGBAST, WGRECORDS, SCICOM Report of the Workshop on Sea Trout (WKTRUTTA) 12-14 November 2013 ICES Headquarters, Copenhagen, Denmark International Council for the Exploration of the Sea Conseil International pour l’Exploration de la Mer H. C. Andersens Boulevard 44–46 DK-1553 Copenhagen V Denmark Telephone (+45) 33 38 67 00 Telefax (+45) 33 93 42 15 www.ices.dk [email protected] Recommended format for purposes of citation: ICES. 2013. Report of the Workshop on Sea Trout (WKTRUTTA), 12–14 November 2013, ICES Headquarters, Copenhagen, Denmark. ICES CM 2013/SSGEF:15. 243 pp. For permission to reproduce material from this publication, please apply to the Gen- eral Secretary. The document is a report of an Expert Group under the auspices of the International Council for the Exploration of the Sea and does not necessarily represent the views of the Council. © 2013 International Council for the Exploration of the Sea ICES WKTRUTTA REPORT 2013 | i Contents Executive Summary ............................................................................................................... 1 Terms of Reference and agenda .......................................................................................... 4 Introduction ............................................................................................................................. 6 1 Research progress .......................................................................................................... 8 1.1 Introduction ........................................................................................................... 8 1.2 Life History Understanding ................................................................................ 8 1.2.1 Introduction .............................................................................................. 8 1.2.2 Rationale and topic overview................................................................. 8 1.2.3 Discussion points from the meeting .................................................... 11 1.2.4 Conclusions............................................................................................. 12 1.3 Interactions between anadromous and non-anadromous trout ................... 13 1.3.1 Rationale and topic overview............................................................... 13 1.3.2 Conclusions............................................................................................. 14 1.3.3 Recommendations for future research ................................................ 14 1.4 Freshwater Phase: Habitat Preferences, Ecology, Behaviour ....................... 14 1.4.1 Introduction ............................................................................................ 14 1.4.2 Recent reviews of research including freshwater phase .................. 15 1.4.3 Recent or continuing programmes including freshwater research ................................................................................................... 17 1.5 Migratory routes and behaviour ...................................................................... 21 1.5.1 Context and progress ............................................................................ 21 1.5.2 Conclusions............................................................................................. 26 1.6 Genetics ................................................................................................................ 26 1.6.1 Progress outline ...................................................................................... 26 1.6.2 Recommendations ................................................................................. 27 1.7 Climate impacts .................................................................................................. 28 1.7.1 Climate change - causes and projections ............................................ 28 1.7.2 Impacts on salmonids ............................................................................ 28 1.7.3 Management response to climate change ........................................... 33 1.7.4 Conclusions and Recommendations ................................................... 34 1.8 Hard structure chemistry .................................................................................. 34 1.9 Sea Trout Research Progress - Conclusions .................................................... 35 2 Gaps in knowledge about threats to sea trout ........................................................ 36 2.1 Introduction ......................................................................................................... 36 2.2 Freshwater survival and production ............................................................... 36 2.2.1 Overview of issues ................................................................................. 36 2.2.2 Conclusions............................................................................................. 37 2.3 Marine survival and migration ......................................................................... 37 2.3.1 Overview of issues ................................................................................. 37 ii | ICES WKTRUTTA REPORT 2013 2.3.2 Conclusions............................................................................................. 38 2.4 Climate change .................................................................................................... 38 2.4.1 Overview of issues ................................................................................. 38 2.4.2 Conclusions............................................................................................. 39 2.5 Overall conclusions on knowledge gaps about threats to sea trout ............ 39 3 Alternative assessment methods............................................................................... 41 3.1 Introduction ......................................................................................................... 41 3.2 Current assessment practice overview and summary of stocks status ..................................................................................................................... 41 3.2.1 Overview of assessment current methods.......................................... 41 3.2.2 Summary of sea trout stocks status ..................................................... 44 3.3 Freshwater assessment ....................................................................................... 49 3.3.1 Overview of issues ................................................................................. 49 3.3.2 Conclusions............................................................................................. 51 3.3.3 Recommendations ................................................................................. 51 3.4 Marine Phase and Adult Assessment .............................................................. 52 3.4.1 Introduction ............................................................................................ 52 3.4.2 Overview of methods ............................................................................ 53 3.5 Genetics ................................................................................................................ 56 3.5.1 Introduction to topic .............................................................................. 56 3.5.2 Recommendations ................................................................................. 57 3.6 The Ecosystem Approach: linking sea trout with Ecosystem Assessments......................................................................................................... 58 3.6.1 The Ecosystem Approach to Fisheries and Ecosystem Assessment ............................................................................................. 58 3.6.2 Ecosystem data and indicators for sea trout ...................................... 59 3.6.3 Sea trout as bioindicators ...................................................................... 60 3.6.4 Conclusions............................................................................................. 60 3.7 Population modelling and Biological Reference Points (BRPs).................... 60 3.7.1 Population models ................................................................................. 60 3.7.2 Assessing fish stocks ............................................................................. 61 3.7.3 BRPs for sea trout ................................................................................... 62 3.8 Integration of data collection to support assessments ................................... 67 3.9 Overall Conclusions and Recommendations .................................................. 69 4 SPATIAL CONFLICTS ............................................................................................... 70 4.1 Introduction ......................................................................................................... 70 4.2 By-catch in marine fisheries .............................................................................. 70 4.3 Mixed stock fisheries .......................................................................................... 71 4.4 Marine renewable energy .................................................................................. 72 4.5 Marine aquaculture ............................................................................................ 74 4.6 Estuarial