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In the middle of 2009, The Tweed Foundation began a major new study on Tweed’s Sea-trout stocks, under the title “Living North Sea”. This is a pan-northern European project comprising 11 other scientific research partners from Scotland, England, Belgium, The Netherlands, Germany, Norway, Sweden and Denmark.
The study is a priority or action in the Tweed Fisheries Management Plan: Policy 2.A (1) - Continue to investigate the stock structure and life histories of the Sea-trout of the District and define any geographical or temporal differences. The advent of the Living North Seas programme has allowed this to be extended into the marine phase, which was not possible before. With the English, Dutch, Danish, Norwegian and German partners in this programme, it is hoped to identify the mixed-stock fisheries around the southern North Sea that exploit Tweed Sea-trout as well as confirm and extend knowledge of the marine feeding grounds that they utilise. The long-term aim of the Living North Seas work is to set up a North Sea Sea-trout group that can oversee the management of the species in the North Sea.
Living North Sea Project / Work Outcomes
• To work out the river and sea distributions and migrations of the Sea-trout of the Tweed catchment and define the marine fisheries that exploit them.
• To allow a properly informed management plan to be drawn up to ensure their sustainable exploitation in the future.
Living North Sea study / Work Description and Objectives
Juveniles
1.1 Maintain & extend database on juvenile trout populations and identify habitat problems that are restricting their spread and production.
1.2 Acoustic tag Sea-trout smolts on the Yarrow and Gala Waters and follow them downstream to assess mortality rates on their way to the sea and identify any problems they may encounter in the river or estuary.
1.3 Read scales of Sea-trout smolts (from the Yarrow trap) to establish age patterns.
Sex ratios of resident and migratory elements (brown & sea-trout)
2.1Kill 100 fully silvered Sea-trout smolts on the Yarrow and Gala Waters to establish sex ratios of outward bound fish.
2.2Trap Sea and Brown-trout in the Gala fish ladder to establish the respective sex ratios of migratory and resident elements.
2.3Run traps on spawning burns to establish relationships between resident and migratory elements of the trout populations of individual burns.
2.4Sample Sea-trout adults near spawning in their home waters to establish their sex-ratio – the regular sampling on the College Burn will allow this.
2.5Near spawning time, when external identification possible, establish sex-ratios of adult Sea-trout caught during exploitation rate tagging at Paxton House.
Adult Sea-trout in the River
3.1 Carlin tag fresh Sea-trout running up river at the Paxton House netting station, to find out exploitation rate by anglers.
3.2 Acoustic tag some of these fresh Sea-trout to establish movement patterns and any problems encountered. In particular, to assess non-angler mortality in the river, which is, at present, unknown.
3.3 Read scales from Sea-trout caught in the river to identify age patterns and spawning frequencies.
3.4 Take scale samples from Sea-trout caught during commercial netting in the estuary to identify age patterns and spawning frequencies.
Sea-trout at sea
4.1Carlin tag Sea-trout smolts on the Yarrow and Gala Waters so these can be recovered at sea to show migration routes. Recovery back in the river will also aid in the interpretation of scale reading patterns.
4.2Net and Carlin tag kelts in Spring, for recovery at sea to show migration routes and, if recovered back in the river, period of absence between spawnings. This will also aid interpretation of scale patterns.
4.3Genetically characterise Tweed trout so that they can be identified when caught in marine fisheries, allowing their marine exploitation patterns to be established and the identification of mixed-stock fisheries for Sea-trout around the North Sea.
4.4Possible participation (with CEFAS) in a programme to put data storage tags on Sea-trout to show the routes they take in the sea.
North Sea connections & relationships
5.1 Contribute data on the characteristics (size, age, run timing, sex-ratios etc) of Tweed Sea-trout for analysis with similar data from rivers around the North Sea to identify patterns and differences.
5.2 Contribute catch record data of Tweed Sea-trout for analysis with similar data from rivers around the North Sea to allow identification of common trends and the relationship of these to physical phenomena such as sea-temperatures, current patterns etc.
5.4 Take samples for genetic analysis from coastal fisheries and from fish merchants (e.g. at Eyemouth) to identify origins of the Sea-trout being caught by fisheries (possible work with NE England EA to cover all major fisheries / merchants in this part of the North Sea).
Publicity & education
6.1 Increase publicity about tagged fish to boatmen, netsmen & anglers to ensure reporting of tagged fish.
6.2 Publicise recaptures of tagged Sea-trout at sea to increase awareness of the marine dimension.
6.2 Use the acoustic tagging programme to publicise the work on Sea-trout generally and increase interest in the species. Public involvement could be through the purchase of tags for use in the work.
The total cost of The Tweed Foundation’s part of the study is £277,186 over two years. The study is attracting a 50% grant from the EU.
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