Looking downstream on the River Cree
Looking upstream on the River Bladnoch
Felling of commercial forestry in Galloway Forest Park
Looking upstream on the River Luce
North American Signal Crayfish
The sandy beach at Loch Grannoch
Belted Galloway Cattle, or 'Belties'
Fly fishing on the River Cree
A small upland burn
The High Cree, looking towards Cairnsmore of Fleet
A small waterfall on the Buchan Burn
A salmon from the Kirkcudbrightshire Dee
We recently returned to the headwaters of the Bladnoch to retrieve egg boxes planted in the river mid-January (see News story ‘Egg-citing Times!’ 18th February).
For the egg box studies to be most effective in demonstrating the influence of water quality/pH on fish egg survival, they must be exposed to a significant spate event as during such times, water pH has been shown to drop below 5 - the critical pH for inhibiting the hatching enzyme of a salmon egg (essentially killing it). Natural buffering of soils and water is very low in the upper Bladnoch. This gives river water that can become unnaturally low in pH and we have seen this from historical water quality data on the upper Bladnoch. Monitoring the effect of isolated spate events on actual fish is fairly difficult (because of the lack of salmon amongst other fish in this part of the catchment). The use of egg boxes is therefore invaluable in monitoring water pH effects on fish during their most sensitive life stage.
The river flow data shown in the graph pictured is taken from the Scottish Environment Protection Agency (SEPA) gauging station on the Cree. This data provides the closest comparison to Bladnoch data (which was not available) and shows that during the time that the egg boxes were in situ, a good number of spate events occurred, including the largest on the 17th February as well as a significant rise on the 1st March.
Providing the augmented river flows produced an acid flush (as we suspect most did), this year’s egg box results are very encouraging. For the Polbae Burn, where two egg box sites were positioned – the upper burn continues to be very healthy and on this occasion, produced an average of 98% survival of eggs to hatching. On the lower Polbae, where survival is usually negligible (because of the influence of the Dargoal Burn), an average of 95% survival of eggs to alevins was recorded! From the graph opposite, you can see that this is the best result for this part of the burn in recent years. Although we have had 100% mortality in the Dargoal Burn egg boxes each year, the boxes were sadly exposed to air on collection this year and for this reason, we cannot be certain that there would not have been signs of life, due to some improvement in water quality as the lower Polbae results would suggest. Never the less, improvements in water quality were also suggested by 96% average survival of alevins within the site draining Loch Maberry and 86% average survival of eggs to alevins below Waterside Bridge on the main River Bladnoch. The control site at Malzie Burn on the lower Bladnoch, continues to provide favourable water quality conditions for salmon production (as we well know from the densities of wild fish produced here year on year).
We shall continue to monitor water quality in the upper Bladnoch using egg boxes when the Bladnoch hatchery is operating.