A’an surveys 2018

The River A’an (Avon) is the largest tributary the Spey and is normally a highly significant producer of smolts. It is a diverse and productive river in its own right although it begins as an extremely low nutrient river with its source in the midst of the granite Cairngorms. Upstream of, and in the vicinity of Inchrory Lodge, the water chemisty benefits from several productive tributaries such as the Allt Loin Bheag and the Allt Loin. In and around the confluences of these tributaries localised pockets of higher fish productivity can be found.

In 2016 the juvenile stock was low, the fry year class of that year in particular was almost missing, this due to the effects of Storm Frank and subsequent high flows. Given the importance of the A’an we repeated some, or all, of the timed surveys in 2017 and 2018.

The blog provides an update on our findings in 2018.

In 2018 we repeated every second (approximately) of the timed sites. The results in 2018 were encouraging. In this table only the figures from sites done in 2018 are shown, but the colour coding from the other sites has been retained as a visual guide to previous years. The main conclusion was that the juvenile stocks were back up to the levels of 2013 with similar fry and parr counts. As in the Dulnain it appears that the upper sites exhibited a more marked improvement. It is worth noting that the fry of 2018 were derived from the 2017 spawning run, the 2017 rod catch in the A’an being one of the poorest on record. More evidence, if it were needed, that there are factors others than the size of the spawning stock influencing the juvenile stock in the Spey.

In the A’an, from about site TA43, which is just below Tomintoul, upstream, the presence of multiple year classes of parr becomes a prominent feature of the salmon population.

Four year classes of salmon. The top one is a fry from this year hatch, with one, two and three year old parr below. The 2017 year class (one year old parr) was found to be strong. In the middle and upper reaches these will not smolt until 2020, or even 2021.

These results were encouraging, the A’an can be expected to be producing good smolt numbers again from next year. The Fishery Board is also seeking to introduce enhanced predation control measures in tributaries such as the A’an, which will only help.

A few more points of interest noted.

Driving back downstream close to Faindouran we noticed this recent gravel deposit from a very small tributary. It looked very fresh as the first decent spate in the A’an itself will shift this downstream. There must have been a localised downpour in the small tributary catchment at some point this summer.

The deer grass has donned its autumn colours early this year. It has been as strange year; the long cold winter which went straight into a long, hot, summer. There is every indication that it is going to be an early autumn.

Site TA84L1, which lies a short distance downstream of the Allt Loin Bheag, and other small, but chemically richer tributaries. This site has always outperformed its position in the river and today was no exception. Amongst the 31 parr captured in the three minute survey were some very well conditioned fish of over 100mm. The river bed in the vicinity of these nutrient inputs is often noticeably greener due to the increased algal growth. Note that in the upper reaches the river was still flowing at full width, the rain over the weekend may may have freshened the upper reaches but not further downstream.

As requested here is the Avon mainstem table as shown above but this time with all the figures.

Avon mainstem 2018 timed surveys wtih all figures included

Authored by: Brian Shaw

There are 5 comments for this article
  1. Euan Reid at 3:42 pm

    Hi Brian, would it be possible to reproduce the colour coded graph above with the actual figures included. Just out of interest.
    Thanks, Euan.

  2. PKJames at 12:06 pm

    Brian
    Thanks for the update and pics of the A’an.
    I have been fishing the middle stretch on a regular basis this year and have been surprised at the amount of water coming down the river despite the near zero rain fall over the period and the early clearance of hill snow.
    In these times is the primary source of water from springs – if not where is it coming from
    Kind regards
    Kevin James

    • Brian Shaw Author at 1:31 pm

      Hi Kevin, When we were surveying in the middle reaches (above Delnabo) we thought the Avon was low, as low as we had seen it, although the following week the flow in the upper reaches was bank to bank. The Cairngorms have been catching some rain recently which would explain that situation. I had a good chat with a farmer in the upper Livet this week, he was commenting that it was only in the last week or two that the water levels had dropped in that part of the catchment. We had previously noted how stable the burns in the Glenlivet area were; they obviously receive a lot of spring water. The geology of the Cairngorms is quite different to Glenlivet, different hydrology too, I suppose?
      Cheers Brian

  3. James leach at 3:06 am

    Informative and encouraging. Thank you for the work and the report.

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