The remainder of the Ayr timed sites were completed yesterday and results were more encouraging than those found on the lower river. I’m relieved to say that on the whole of the upper sites performed reasonably in complete contrast to sites on the lower river.
There may be many reasons for this, not least the prolonged spate conditions that prevailed last winter and until we’ve looked at all the rivers to see how they fared, I won’t be drawing conclusions yet.
The sites at Limmerhaugh, Nether Wellwood and upstream of Muirkirk all produced good numbers of salmon fry with fry per minute. The new upper river site below the Ponesk confluence was excellent and produced 172 fry in 5 minutes (or 34.4 fry/m), more than double the result from 2013 of 16.8 fry/m. Let’s hope this continues to produce such excellent results in future but I remain concerned as iron oxide is visible on the river bed in this area. The lower Ponesk appears to be the source of this as in recent weeks, I’ve noticed iron oxide arising from upwelling groundwater as the water table rebounds following the coal extraction. This may reduce the quality of spawning beds on the main steam downstream of the confluence depending on how severe this enrichment becomes. The Stottencleugh upstream a short distance, suffers terribly from this pollution and egg survival was recently recorded at 0%.
Nether Wellwood results were good at 17 fry/m but way below the 28.2 fry/m recorded in 2009 and down on last years results of 24.6 fry/m. In poor years numbers have dropped to as low as 6.8 fry/m, so while not at it’s peak, this site is certainly important and productive. Whilst at this site we noticed heavy pollution stemming from the Powharnol Burn. Cattle were seen in the burn upstream and I reported this to SEPA who will investigate. This type of pollution contributes to reduced water quality and increased silt on the river bed and that impacts spawning success.
This year we have been looking at the number of pollution tolerant species that we find in comparison to the salmon and trout numbers. It is quite shocking to think that the humble beardie (Stone loach) may make up the greatest biomass of fish in many stretches of our rivers but particularly in areas where pollution is increased. At nether Wellwood, we recorded 85 salmon fry, 6 parr and 4 trout (a total of 95 salmonids). Stone loach totalled 217, more than double the salmonid population. Come the winter, I intend to look more closely at these results and see what I can find out about competition between stone loach and salmon populations. I know there has been limited studies looking at minnows and how they may impact salmonids so I wouldn’t be surprised if there has been studies on stone loach too.
Limmerhaugh has been one of the most productive sites we’ve survey over the years and on the whole it’s been consistently good but 2014’s were excellent with 31.0 fry/m (the best on record).
We have yet to undertake the timed surveys of Lugar side of the catchment and will do this once we have our electrofishing kit repaired (yet again it has packed up for no apparent reason).