Burn of Lochy

It has been very busy recently and I have been juggling electrofishing, stocking, preparation for the Aberlour meeting and a bit of fishing!

Today we carried out four electrofishing surveys in the Burn of Lochy catchment. The Lochy is a good sized burn which joins the Avon a few miles downstream from Tomintoul. There was one established electrofishing site in the lower Lochy but in order to get a better picture of the fish population in the burn we surveyed a new site about 1km upstream and two new sites on the Allt Iomadaidh, a tributary of the Lochy which had never been surveyed before.

The established site on the Lochy was just upstream of the road bridge at Inverlochy. Habitat was classified as moderate only as all along the left bank was a big slab of bedrock providing little or no cover for fish. Despite this the results were good. In a stretch 29m long, with an average width of 5.2m we found 53 salmon parr and a lesser number of fry and trout, and one eel.

The Scottish Fisheries Classification Centre score for the site this year and in previous surveys is shown below.

Electrofishing results from Burn of Lochy A3 site

The results in 2012 were excellent for salmon parr and were similar to those recorded in 2003 and 1997. The relatively low numbers of salmon fry found in the site were of no concern, there are abundant spawning grounds a short distance upstream.

Burn of Lochy Site A3. The bedrock along the left bank can be seen.

The new site was at the top end of Inverlochy Farm fields (thanks to the farmer for giving us permission to drive up). The habitat here was more typical of the Lochy with a boulder and cobble bed and a variety of flow and depths. We surveyed a site 41.6m long with an average width of 5.2m. The lower end of the site had a deepish run/pool below an alder root whilst the upper end was a fast flowing run over cobbles.

Lower end of site A3a Burn of Lochy

 

Burn of Lochy site A3a upper end

In this site we found a lot of fish: 93 salmon fry, 77 salmon parr, 33 trout fry, 18 trout parr and 2 eels. I didn’t take any photos of the fish as the midges were by this time horrendous. The Avon “Skin so soft” was far from soft, in fact it had gone solid with the cold in the van and by the time I had got it liquid again we had finished the measuring of the fish and we cleared up as quick as possible. The results from this site were good to excellent for all categories (see below).

Further upstream the Lochy is formed where the Burn of Brown and the Allt Iomadaidh join at Bridge of Brown. As far as I could establish we had never surveyed the Allt Iomadaidh although it was known to be accessible to salmon and sea trout for a considerable distance. Accessing the burn required a walk (maybe that’s why it hadn’t been surveyed!) but that was no hardship. We did two sites separated by a short distance. The upper site was above the wooded area on the fringe of the moorland. It looked like a cracking burn and it didn’t take long to confirm that salmon were present in good numbers. In a site 43m long with an average width of 2.2m we found 20 salmon fry, 20 salmon parr, 13 trout fry,  35 trout parr and 2 eels.

The Allt Iomadaidh turned out to be a perfect little hill burn with undercut banks, moss covered rocks and a variety of flows. Just above our survey site was a long pool (stuffed with parr) which had a perfect gravelly tail for a salmon to cut a redd.

Allt Iomadaidh, a cracking Spey hill burn

The lower site was in the birch woodland. Here the results were also good. In a site 28.3m long, average width 3.3m, we found 9 salmon fry, 23 salmon parr, 8 trout fry and 27 trout parr.

Allt Iomadaidh lower, site A33

The SFCC classification for these three sites are shown in the table below.

Burn of Lochy upper and Allt Iomadaidh electrofishing results

Steve had told me the Lochy was a productive burn and today’s surveys confirm this nicely. The salmon parr densities at all four sites were in the excellent category. Based on the results from today I estimate that the absolute minimum number of salmon parr present in the Lochy and Iomadaidh will be 10,000. There were good number of 2+ salmon parr although most were as usual 1+.

Apart from the midges it was a very enjoyable and satisfying day; it was good to get away from the politics for a while!

 

There are 2 comments for this article
  1. Jock Royan at 6:59 am

    Hi Brian,

    Another very detailed report with again some optimistic findings. I believe the SFCC classifications are a comparison against other rivers in Scotland alone. Whilst there are clearly many ‘green zones’ within your graph, we must consider that the salmon population in Scotland has, in the majority of rivers, been in decline for the past 25 years. Do you think it would be fair to say that purely considering current densities, the green zones that you show might well have been red zones if surveyed in the 70’s?

    See you next Tuesday,

    Jock

    • Brian Shaw Author at 8:13 am

      Hi Jock,

      Not all our surveys have been so good but I will report all the results at the meeting next week.
      Your point about current fish densities compared to past is a good one. I know for sure that in marine fisheries each new generation of fisheries scientists has a new lower reference point than generations before. I can’t find it now but when I arrived here someone sent me a copy of an article making that very point.

      However salmon and trout populations have always been limitied by density, they are territorial so each fish needs a certain amount of space to survive. The ultimate density will be affected by egg input, habitat quality and food availability. There is a not a long history of electrofishing but the Spey has some paper records that date back a good few years. When I get a chance I must try and compare some of the old stuff with the more recent. I must ask the Tweed what their fish densities have been like over the last two years, the recent runs of fish there were good in a historical context.

      One of the Spey ghillies was telling me he used to live at Inverlochy Farm and that when he arrived here 18 years ago some of the pools in the lower Lochy were thick with salmon waiting to spawn. It hasn’t been the same in recent years. That could be explained by marine survival: you could have the same smolt output as in the past but lesser numbers of returning adults. Regarding marine survival I have some interesting data from the Marine Scotland Science research on the North Esk which I will present next week. There has been a significant improvement in marine survival of smolts in the last few years, we saw that with the 2009 Spey smolt year class. But it could be argued that the Spey hasn’t capitalised fully on this apparent improving situation. Hopefully we can discuss this next week.

      Brian

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