After a couple weeks of trying access permission and low water combined on the same day to allow us to complete an electrofishing survey in the upper Dulnain at a site we call the Suspension Bridge. The altitude was over 1500′ but the habitat looked excellent. Conductivity was only 13 so the fish were not attracted to the ring for long and we missed a few parr.
We had already completed a timed survey in the area but we needed a density survey result to provide an indication of the parr density. It is quite an adventure getting to the site with a 40minute drive over the hill road. (We have a school work experience girl with us this week. She was videoing the journey home on her phone so I wonder if her mother will let her back tomorrow for her last day!) It appeared to be a game rich estate as there were numerous coveys of grouse rising from the road side and stags bellowing on the way home. There were pheasants galore down by the wood but they don’t really count! Anyway we were more interested in the salmon so we set about surveying the usual site just below the remains of the old suspension bridge.
Despite using a high voltage setting quite a few fish got away. However in a site 12m long we captured 38 salmon fry and 4 salmon parr with a few trout.The site area was 136.6m2 giving densities and classification results as below.
Salmon densities have been variable at the site, although generally in the low classes. The 2012 salmon fry result was the best found at the site although the parr density was in the poor class.
I would have expected more parr in such good habitat. We did a second run catching plenty more fry but no parr. The habitat at the site was excellent for parr, with a variety of flows and a good mix of boulders, cobbles and pebbles providing plenty cover. The substrate looked stable with moss growing on many of the boulders and a coating of algae for the grazing invertebrates. Previous parr densities have been up and down over the years without ever being excellent but there were quite a few fry found last year to provide the base of the pyramid. It is obviously a harsh environment at such high altitude but an invertebrate kick sample found moderate numbers of stoneflies and immature heptagenid mayflies indicating that acidification isn’t an issue. Maybe it is expecting too much to see good/excellent parr densities so high up the system but it is encouraging to see good fry numbers this year. The data set has gap years so it isn’t really possible to see any clear pattern between fry numbers one year and parr the next. 2011 was one of the best parr years despite very poor fry numbers in the previous three years?
I had a short walk upstream whilst the fish were being processed. The gradient in the immediate locale was a bit high and the substrate too coarse to provide ideal spawning grounds but the Dulnain does its own thing up here and there would no doubt be good spawning sites within a short distance. There may not have been any big spawning fords in the area but there were small pockets of spawning gravel which could be used by individual hens.
This was the last electrofishing survey of the season (except some ongoing monitoring planned for the mainstem) and it was a bit of a treat for me to see this part of the Spey catchment. It really is big country when you climb the hill above Loch Insh. It wasn’t a great day for panoramic views of the hills, which was just as well as I’d left my good camera at home. I look forward to visiting the upper Dulnain again on a nice sunny day.