Yesterday Michael sorted through the invertebrate sample collected from the Feshie. The Feshie is quite different in character to the other parts of the Spey catchment where we have sampled the invertebrates. The Feshie runs directly from the Cairngorms, water chemistry, temperature and flow regime will be quite different to the mainstem or lower tributaries such as the Livet for example. I expected the invertebrate sample to be of lesser abundance and that is what we found.
Whilst collecting the sample it was immediately obvious that there was not the same quantity of organic debris trapped within the cobbles and it was virtually silt free, as a result the sample was relatively easy to sort through.
In comparison to the samples from the Spey mainstem and the Livet the invertebrate population in the Feshie was relatively sparse. The total abundance was 295 individuals. The BMWP score was 95 but the Average Score per Taxa (ASPT) was 7.3, the highest from any of our sites so far. So there were few individuals but they were high scoring, i.e. species sensitive to pollution.
Incidentally I noted the same small caddis on the rocks in the Spey at Knockando the other evening. The riverbed rocks were absolutely covered with very small grannom cases, the big hatch experienced a few weeks ago must have resulted in a huge recruitment of juveniles. If they survive it looks like there could be another big hatch next spring.
We will continue to collect samples from across the catchment and at the end of the summer I will show all the photos showing the sorted samples in the dishes for comparison. It should be clear that the invertebrate productivity of the Feshie is naturally much lower than the Livet; its the same for the salmon fry and parr.