STATUS OF THE RIVER TANA SALMON POPULATIONS REPORT 1-2012 OF THE WORKING GROUP ON SALMON MONITORING AND RESEARCH IN THE TANA RIVER SYSTEM Contents 1 Summary ......................................................................................................................................... 4 2 The group mandate and presentation of members ..................................................................... 10 3 Introduction .................................................................................................................................. 11 4 The River Tana, the Tana salmon, salmon fisheries and management ........................................ 12 4.1 The Tana and its salmon ....................................................................................................... 12 4.2 Tana salmon fisheries ........................................................................................................... 17 4.3 Management of the Tana salmon fishing ............................................................................. 28 5 Local/traditional knowledge and local contact ............................................................................. 29 5.1 How the Group will approach these issues........................................................................... 29 5.2 Current locally raised issues .................................................................................................. 31 5.2.1 Predation ....................................................................................................................... 31 5.2.2 Natural variation ........................................................................................................... 36 5.2.3 Increased tourist angling ............................................................................................... 37 5.2.4 Decreased number of gillnets ....................................................................................... 37 6 Threat factors ................................................................................................................................ 38 6.1 Gyrodactylus salaris .............................................................................................................. 38 6.2 Proliferative kidney disease .................................................................................................. 38 6.3 Cottus gobio .......................................................................................................................... 38 6.4 Escaped farmed salmon ........................................................................................................ 39 6.5 Water quality ........................................................................................................................ 40 6.6 Overexploitation ................................................................................................................... 40 6.7 Paralithodes camchaticus ..................................................................................................... 44 7 Stock monitoring ........................................................................................................................... 45 7.1 Catch sampling ...................................................................................................................... 45 7.2 Monitoring of the main stem mixed-stock fishery ............................................................... 45 7.3 Fish counting ......................................................................................................................... 49 7.4 Juvenile monitoring............................................................................................................... 50 8 Research projects .......................................................................................................................... 52 8.1 Kolarctic Salmon.................................................................................................................... 52 8.2 Fisheries Evolutionary Genomics: Tana salmon as a model system ..................................... 52 8.3 PIT-tagging of juvenile salmon in small streams ................................................................... 53 8.4 Biology and exploitation of sea trout.................................................................................... 56 8.5 Development in the use of stationary gear in Tana .............................................................. 57 9 Stock status evaluation ................................................................................................................. 60 9.1 How to evaluate stock status? .............................................................................................. 60 9.2 Salmon production and spawning targets ............................................................................ 60 9.3 A procedure for target-based stock evaluation .................................................................... 63 9.4 Explanation of terms (glossary) ............................................................................................ 67 9.5 Tributary-specific stock evaluation ....................................................................................... 68 9.5.1 Máskejohka ................................................................................................................... 68 9.5.2 Lákšjohka ....................................................................................................................... 70 9.5.3 Válljohka ........................................................................................................................ 73 9.5.4 Iešjohka ......................................................................................................................... 74 9.5.5 Kárášjohka ..................................................................................................................... 76 9.6 The importance of spawning target attainment ................................................................... 78 9.7 Tana stocks vs. neighbouring rivers ...................................................................................... 80 9.8 The unique problem of sequential accumulated exploitation.............................................. 81 9.9 Management recommendations in light of the stock status ................................................ 83 9.10 Management evaluation in light of the stock status ............................................................ 85 10 Monitoring and research needs ................................................................................................ 88 10.1 Long-term monitoring recommendations ............................................................................ 89 10.1.1 Fish counting ................................................................................................................. 90 10.1.2 Catch samples ............................................................................................................... 91 10.1.3 Stock identification ....................................................................................................... 91 10.1.4 Juvenile production ....................................................................................................... 92 10.2 Short-term monitoring recommendations for 2012 ............................................................. 93 10.3 Other research needs............................................................................................................ 93 11 References ................................................................................................................................ 94 Tana research & monitoring group, report 1-2012 4 1 Summary The Group and its mandate The permanent monitoring and research group was formally appointed in 2010 by the Ministry of Agriculture and Forestry in Finland and the Ministry of Environment in Norway, based on the Memorandum of Understanding signed in February 2010. Among other points defined in its mandate, the Group should deliver annual reports on the status of the salmon stocks, evaluate their management, and give advice on relevant monitoring and research. This is the first report of the group. The Tana, its salmon stocks and fisheries The subarctic River Tana forms the border between northernmost Norway and Finland. The river drains an area of 16 386 km2 consisting of a multitude of small and large tributaries, most of which (>1 200km) are readily accessible for ascending salmon. The river Tana is also one of the few remaining large river systems that still support abundant Atlantic salmon stocks with little or no human impact to the system, except for fishing. Tana today supports the largest wild stock of Atlantic salmon in the world, with annual river catches fluctuating between 70 and 250 tonnes, equivalent to an average of 30-50 000 salmon being harvested annually. The total salmon stock with a minimum of 30 different populations consists of a wide variety of life histories. The sea-age groups are ranging from one-sea-winter to five-sea-winter salmon, with various types of previously spawned fish. Proportion of escaped farm fish in the Tana salmon catches has so far been very low, although their proportion after the fishing season is not known (with some few exceptions). The riverine salmon fisheries in Tana include net fishing methods such as weir, gill net, seine and drift