Avon spawning recce

Steve and myself, accompanied by a local photographer interested in salmon, headed for the upper Avon (A’an) today to check on the spawning activity.  This was the same trip as we had made three years ago although on the 24th Oct, a week earlier.

The first port of call was the Burn of Loin a productive high altitude tributary of the A’an.

Typical habitat in the upper Loin

Typical habitat in the upper Loin. It is quite a mobile burn, a trait accentuated by the big spate last year although it didn’t look too dissimilar to what we had seen in 2012.

There were redds visible from the start on our walk with fish present on some. James deployed his Gopro underwater cameras at the first two locations where we found actively spawning fish; hopefully he will have got some good footage. In total we walked 2.8km counting 67 salmon redds and 21 which we thought we more likely made by sea trout; although we didn’t see any live sea trout today, almost all the fish which we could identify were grilse with the occasional larger salmon. In the middle reaches every bit of spawning gravel had been turned over.

Well used spawning gravels in the Loin.

In the middle reaches of the Loin almost every inch of suitable spawning gravels had been turned over, including this well ploughed patch.

A grilse on a Loin redd.

A grilse on a Loin redd.

This was the only positive sighting of a sea trout today; a dead one on the bank. Presumed to be an otter kill although each end appears to have been sucked rather than chewed?

This was the only positive sighting of a sea trout today; a dead one on the bank. Presumed to be an otter kill although each end appears to have been sucked rather than chewed?

Last year we noted that whilst the nearby Builg Burn held mainly spawning two sea winter salmon the Loin fish were mainly small grilse. It was the same this year. Still they were present in good numbers and we were more than satisfied that the egg deposition target would have been more than met in the Loin.

In addition to the redds count the bird count included one eagle, several dippers  and of all things a goosander!

Satisfied with the Loin we headed upstream to the upper A’an. I blogged about the 2012 trip to the same area see here so it was going to be interesting to see what was about this year. We got to the end of the road at 1220, grabbed a quick sandwich then headed upstream to take advantage of the good light. As in 2012 we found redds immediately next to the bothy, although if anything there seemed to be more fish and redds in that area this year.

There were four identifiable redds in this area with five fish in attendance, a good level of activity for such high altitude.

There were four identifiable redds in this area with five fish in attendance, a good level of activity for such high altitude.

In 2012 we found a "mega redd" where large rocks had bene dislodged. Well we found the same this year. These two excavations midstream involved moving rocks up to 8" diameter. It is almost unbelievable that salmon could move such material but what else would dig holes in the river bed at 2000ft?

In 2012 we found a “mega redd” where large rocks had been dislodged. Well we found the same this year. These two excavations midstream (white patches above centre) involved moving rocks up to 8″ diameter. It is almost unbelievable that salmon could move such material but what else would dig holes in the river bed at 2000ft?

This photo was taken in a side channel just below where the Allt Coire Ruairidh joins the Avon. There were two redds in this fine patch of spawning gravel with a cock grilse on guard; it was exactly the same in 2012, check out the link provided above.

This photo was taken in a side channel just below where the Allt Coire Ruairidh joins the A’an. There were two redds in this fine patch of spawning gravel with a cock grilse on guard; it was exactly the same in 2012, check out the link provided above.

The Allt Coire Ruairidh confluence. There were four redds in this frame, a nice wee cluster at over 2000ft altitude.

The Allt Coire Ruairidh confluence. There were four redds in this frame, two in the foreground and two behind the grassy island, a nice wee cluster at over 2000ft altitude.

30 salmon redds were recorded in 2.7km of river, a much lower density than in the Loin but the upper A’an is considerably higher and considerably less productive. In 2012 we counted 25 redds but saw less fish than today, albeit a week earlier. This part of the upper A’an is maybe on the very limit of salmon survival in terms of altitude and lack of productivity. Again we were happy with what we saw.

terrain blog 2

Contrary to the forecast the weather improved during the day with the clouds clearing to reveal a beautiful autumn afternoon light. The low sun really highlighting the fantastic glacial features of the terrain.

There are 7 comments for this article
  1. John Carmichael at 2:49 pm

    Hi Brian,
    It was clear from your redd surveying that low clear water enabled you to get the best count results in those smaller upland waters.
    Is low or normal water height the optimum level for spawning ie for egg survival ?
    Or do fish know to spawn only in certain depths and flows which will ensure good egg survival?

    • Brian Shaw Author at 3:55 pm

      Hi John, good question. The risks to eggs on the Spey during incubation are washout or drying out. Some fish do spawn in areas where part of the redd at least becomes exposed during low water, although the bottom of the redd, where the eggs are, is generally still submerged. However, in those circumstances water exchange through that gravel must be diminished. So spawning during high water could potentially leave more redds prone to drying out.
      Salmon spawn in a variety of depths from barely covering their back to several feet deep, it depends very much on the availability of suitable gravel and flows. There has to be a reasonable flow otherwise any gravel displaced by the hen during redd cutting would just settle back in the same place rather than be carried downstream slightly by the current. Low water restricts the area of suitable spawning habitat therefore normal water height probably provides the optimum combination of habitat and safety.
      In areas subject to diffuse pollution problems egg incubation survival in sub-optimal habitat could be very poor; we are fortunate in that respect in the Spey, siltation levels are generally low.
      Best regards
      Brian

  2. Ross Wood at 12:34 pm

    It is a stunning part of the country Brian – was up Bynack More last time home and the terrain looks very similar to the other side of Bynack More into Strath Nethy – Is Loch Avon too high for salmon to reach?

    • Brian Shaw Author at 5:45 pm

      I don’t think there are any barriers Ross so they possibly could reach there. Yesterday Steve was telling me about a day 20 years ago when he and a colleague walked from Loch Avon to Tomintoul, including the climb up from the Cairngorm carpark as the ski lift was not working – a monumental walk! He does recall though that there were no redds until Faindouran, much the same as nowadays. There are trout in Loch Avon so there is no reason why salmon couldn’t survive there but they don’t appear to.

      • C King at 6:21 pm

        Hi Brian

        Wonderful part of the world, thanks for the report.

        A thought about trout / salmon: Don’t forget that according to Crisp (1999), trout are better adapted for cold than salmon by 2 to 3 degrees, they will continue to feed down to 3 deg C whereas salmon may stop at 6 deg. Optimal feeding for trout is around 13 deg vs 16 deg for salmon. Trout will have a longer growing season therefore. Could be that at those elevations, and on average, salmon fry are too limited by constraints to growth and cannot effectively compete with the trout?

        • Brian Shaw Author at 8:41 pm

          Hi Chris, I hear what you are saying but at the highest Avon quantitative electrofishing site more juvenile salmon than trout were recorded during both surveys and in none of the mainstem Avon timed surveys did trout outnumber salmon. I associate these high altitude sites with salmon rather than trout. Trout spawn, and presumably emerge as alevins, a good few weeks earlier, than salmon, something presumably they can do because of the cold water adaption, but that doesn’t seem to confer on them any particular high altitude advantage.
          Cheers Brian

  3. James Leach at 9:42 pm

    I greatly enjoy reading these and the river reports. Thank you for all the miles walked and the observations made.

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