Fisheries reports positive limestone results

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Last week saw the Galloway Fisheries Trust (GFT) complete the third phase of their High Cree Limestone Gravel Project.

The Cree headwaters used to support a healthy salmon population, but by the mid 1980’s fish stocks had plummeted here as the water became acidified - the blanket afforestation with Sitka spruce of much of Galloway’s uplands and the lack of buffering (to neutralise the acidity, which kills young salmon stocks) in surrounding soils exacerbating the effects of acid rain falling on the catchment.

Limestone works on the Cree.

Limestone works on the Cree.

It was GFT research, completed with local district salmon fishery boards, which highlighted that acidification was decimating these headwater fish stocks.

About 70 percent of reported Scottish acidification is found here so, unsurprisingly, it is believed that about a decade ago, salmon actually died out across all of the High Cree (the headwaters of the River Cree). However, since then water quality has been gradually improving due largely to a combination of reducing air pollution and the restructuring of Galloway’s forests to higher environmental standards. A key role of the GFT has been to identify where conifer planting is downgrading water quality and then to persuade a range of forestry interests to improve matters. The Forestry Commission now have an ongoing programme whereby when an ‘old style’ blanket Sitka spruce plantation is felled and the new replacement planting is far more sympathetic to the environment.

This often involves wider tree-less buffer zones round water courses, more deciduous (broadleaved) tree planting and in some cases not replanting at all on the higher ground where acidification impacts are worst. Such changes will lead in time to improvements in water quality but it may take many years. Organisations like GFT, SEPA, SNH and local District Salmon Fishery Boards can input to these restructuring plans. Although improving water quality had led to a mild improvement in young fish stocks (especially brown trout in Galloway’s hill lochs), acidification remains the main constraint on salmon productivity in the headwaters of the Bladnoch, Cree and Water of Fleet and more needs to be done to ensure wild fish stocks can thrive in the areas they used to inhabit. The GFT started the High Cree Limestone Gravel Project, with the support of the Cree DSFB, to examine the practicalities and benefits of undertaking targeted limestone gravel addition to improve the survival of the young life stages of salmon which are most vulnerable to low pH flushes.

Limestone gravels (of a size mix suitable for salmon and trout spawning) have been added to the river to create spawning beds which increases the water pH and calcium levels (calcium helps fish cope with acidification) within the gravel beds, helping salmon eggs to survive and hatch.

In total, 1315 tonnes of limestone gravel has now been introduced to the High Cree. The total cost of this project, including the required monitoring, has been roughly £80,000 to date. This year’s work has been part-financed by GFT, the Scottish Government and the European Community, Dumfries and Galloway LEADER 2007 – 2013 Programme and the SEPA Water Environment Fund and indirectly – through their support of GFT – by the Cree DSFB. The effects were monitored closely by GFT and SEPA through a combination of water quality testing, egg box experiments and electrofishing and it is encouraging to report that overall the findings have been positive. It is planned that similar work will continue locally to assist the on-going recovery of the Galloway rivers headwaters.

The added limestone has been found to mix well with natural river gravel and has become incorporated into a number of key spawning beds. In the summers of 2012 and 2013 electrofishing found good numbers of salmon and trout fry (young fish under a year old) at many of the limestone gravel addition sites showing that wild fish have successfully spawned in them. At one site on the High Cree, 70 salmon fry were recorded in a 10 metre long section of the river. This summer’s electrofishing also found salmon parr (young fish over a year old) showing that the fry from 2012 had successfully survived over the winter. Members of the High Cree Game Fishers have also reported catching salmon parr this summer while they were trout fishing. Further, after many years of no adult salmon being caught by anglers on the High Cree, it was encouraging to hear that a couple were caught by trout fisherman in 2012 and on the 28th September 2013 a 5.5lb cock salmon was caught by Frank Brierley (a member of the High Cree Game Fishers) at Dalnaw close to where the limestone was added.

Jamie Ribbens, GFT Senior Biologist said: “We are encouraged by the findings of the limestone gravel project so far. This work aims to assist in the return of wild salmon back to the High Cree which is essential for the overall health of the Cree system. In the longer term of course, it is the improving air quality and restructuring of conifer plantations which is needed to fully recover Galloway’s acidified waters but in the meantime the limestone work is one initiative which aims to help speed up the on-going recovery. I would like to thank the various landowners and SEPA who have helped in the project.”

To find out more about the liming project and to be kept up to date with the work of the Galloway Fisheries Trust check the ‘news’ section of their website