Fish take precedence in innovative new flow regimes for hydro-river

In an unprecedented move, the pattern of water flows in Argyll’s biggest river, the Awe, which has been harnessed for hydro since the late 1950s, has been fundamentally revised with the aim of improving fish spawning opportunities and juvenile fish numbers. Previously the compensation flows and release of freshets from the Awe Barrage dam, agreed between the operator Scottish and Southern Energy (SSE) and the river owners, were high in summer (for the benefit of angling) and low in winter – the exact reverse of the natural situation.

In 2010, when concerns were raised on whether the existing flow regime was ideally suited for juvenile salmon, SEPA convened a working group including representatives from SSE, wild fish interests and local proprietors to examine existing arrangements and how they might be improved. The Argyll Fisheries Trust collected evidence of spawning patterns in the Awe and correlated them with flow data. This was the basis for extensive negotiations between the interested parties, culminating in an agreement on a new flow regime to operate from late spring 2012; this involves reducing the summer flow in order to cater for extra water in the winter.

Alan Kettle-White, Senior Biologist for the Argyll Fisheries Trust, explained: “Our study concluded that the old flow regime, with reduced flows in the autumn, was likely to limit access for adult salmon and trout to the available spawning beds. Conversely if it is wet and there is considerable extra water in the river, salmon will spawn in all available areas but the resulting eggs are left high and dry once the flows revert to the low winter compensation regime. At this time of poor marine survival – which limits the number of adult salmon returning each year – it is vitally important to maximise spawning opportunities, juvenile recruitment and the number of smolts migrating to sea. We believe that the new flow regime will assist in this regard and provide a basis for restoring degraded spawning sites in the future.”

Tony Huntington, Chairman of the Awe District River Improvement Association, commented: “Whilst high summer flows are advantageous for angling, it would be wrong of us to continue with such water conditions if in effect we are taking water which is needed in the autumn and winter for spawning and juvenile fish. And in the end, without good juvenile populations migrating to sea, the numbers of returning adult salmon, on which angling depends, will not be at optimal levels. This initiative will only be successful if in the future SSE modify their spillage policy – by not holding back water and then letting down extreme floods which wash out the redds.”

Richard Fyfe, Specialist in Water Resources at SEPA, said: “Following the introduction of the Water Framework Directive SEPA now has the role of regulating how water is used by hydro-schemes and determining what flows are required to deliver ‘good ecological status or potential’. We are pleased that this new flow regime has been agreed on the basis of the best available evidence and a very positive collaborative approach by all the parties concerned.”

Dr Alastair Stephen, Senior Ecological Advisor at SSE, added: “There has been a level of recognition, indeed a consensus, that the primary consideration must be the ecology of the river rather than the angling. We hope that this initiative will be a forerunner of other co-operative approaches to similar issues on other rivers, and that this adaptive management concept will be taken on board by the regulatory arm of SEPA in the wider context of helping to deliver further improvements as required under the terms of the Water Framework Directive.”

Jamie McGrigor, Highlands & Islands MSP, who has a share in a fishing syndicate on the River Awe, said: “For ages it has crossed the mind of many of us here that it must be bad for the ecology of the River Awe if it is reduced to a trickle from October to April. At the time when the original spillage regime was agreed in about 1960 salmon, grilse and sea trout were so abundant that the main concern was over how to maximise fishing effort during the open season rather than attempting to ensure the sustainability of the stocks for the future. Now things are very different and I am glad and grateful that our tenant fishermen are willingly sacrificing some of their fishing benefits and comfort zones in an effort to secure a sustainable future for the River Awe which, as those of us who fish it will know has such an exciting history, especially of big fish which Calderwood referred to as ‘lusty fellows’. It will take several years to know if this experiment will work but it is marvellous to have achieved the cooperation and good will of SSE, SEPA, scientists and fishermen as well. It may be a blueprint for the future.”

A monitoring programme will evaluate the effectiveness of the new flow regime and allow further evidence-based changes in subsequent years.

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