Avon mainstem surveying Day One

This year we are surveying the Avon (pronounced A’an) intensively as part of the three year catchment rota. The Avon mainstem is too large to survey effectively by quantitative surveying so we used the same fry index survey technique as used on the Spey mainstem. The protocol is identical to that used in the Spey mainstem survey so the results will be directly comparable. As this technique has not been used on the Avon before the only benchmark are the Spey mainstem results

Today we completed 6 sites, 5 on the Avon and 1 in the lower Livet for comparison. Normally we would expect to do more sites using this type of survey but we needed to select suitable survey sites and access, plus we found a lot of fish! To aid site identification the river was split the river into 500m long sections numbered sequentially from the confluence upstream. There are 120 x 500m sections and we wanted a survey site approximately every 2.5km.

Our first site was opposite Ballindalloch Castle in the lower reaches. Ideally we want sites that will be resilient to a range of flows so that factor had a heavy bearing on our site selection.

Lower Avon site, downstream of Balnellan Pool at Ballindalloch Castle

Lower Avon site, downstream of Balnellan Pool at Ballindalloch Castle. The results from this site were good with 116 salmon fry and 65 parr.

The next site was upstream of the Ballindalloch Filling station next to the golf course. Here the substrate was coarser but it was very productive.

Upstream of the Ballindalloch Filling station. The substrate here was coarse, more suited to parr but we still found 119 fry. The habitat suited parr and the results didn't disappoint with 85 parr captured, making it the second best parr site so far this year.

Upstream of the Ballindalloch Filling station. The substrate here was coarse, more suited to parr but we still found 119 fry. The habitat suited parr and the results didn’t disappoint with 85 parr captured, making it the second best parr site so far this year.

The Avon gillie Alan Thomson helped us with the site selection on the upper part of the Ballindalloch Estate water. The third site was below the Haugh Pool in Beat 3 (a lovely looking bit of water).

Site below Haugh Pool. This produced 124 fry and 31 parr.

Site below Haugh Pool. This produced 124 fry and 31 parr, even though the flow was slowish; it was verging on glide rather than run/riffle.

The next site was the riffle between the Kelt Pool and Gray’s Run towards the upper end of the Ballindalloch Water.

Perfect fry habitat below the Kelt Pool. The results were good and a recount was required to establish that we had caught 249 fry and 21 parr.

Perfect fry habitat below the Kelt Pool. The results were excellent and a recount was required to establish that we had caught 249 fry and 21 parr.

One more site was completed upstream of the Livet confluence. Only 67 fry here but 47 parr. The substrate in the Avon is brilliant for juvenile salmonids with lots of small boulders with spaces around and below, there is an abundance of cover throughout the section we surveyed today.

One more site was completed upstream of the Livet confluence. Only 67 fry here but 47 parr. The substrate in the Avon is brilliant for juvenile salmonids with lots of small boulders/large cobbles with spaces around and below; there was an abundance of instream cover throughout the section we surveyed today.

On the way home we stopped where the bridge at Drumin crosses the lower Livet. I have often admired this river vista whilst traversing the bridge so it was a pleasure to complete a site in the warm sunshine just upstream of the road.

Beautiful habitat upstream of Drumin Bridge in the lower Livet. We surveyed for 3 minutes on the right side of the channel towards the top of the photo. The Livet is known to be one of the best spawning tributaries in the Spey so expectations were high. The results were good with 207 salmon fry and 14 parr. The fry and some of the parr were noticeably larger than in the Avon. We also found 8 trout fry and 2 parr, a good number for a survey in a channel that was over 25m wide.

Beautiful habitat upstream of Drumin Bridge in the lower Livet. We surveyed for 3 minutes on the right bank side of the channel towards the top of the photo, probably covering about 10% of the area shown in the photo. The Livet is known to be one of the best spawning tributaries in the Spey so expectations were high. The results were good with 207 salmon fry and 14 parr. The fry and some of the parr were noticeably larger than in the Avon. We also found 8 trout fry and 2 parr, a good number for a survey in a channel that was over 25m wide. Based on the results the small area shown in the photo probably holds around 2000 fry and hundreds of parr (the majority of the areas we fished were the shallow parts more suited to fry).

 

Steve and Michael processing the Livet catch. We always try to take advantage of any elevated bit of ground, or inthis case a bench to provide a little relief for the knees and back whilst measuring the catch.

Steve and Michael processing the Livet catch. We always try to take advantage of any elevated bit of ground, or in this case a bench to provide a little relief for the knees and back whilst measuring the catch.

Measuring some of the catch for the Livet.

Measuring some of the catch from the Livet.

A Livet salmon parr of 135mm and a similar size trout parr.

A Livet salmon parr of 135mm and a slightly smaller trout parr.

This was a very interesting day as we hadn’t used this survey technique before in the Avon. The mean salmon fry number from the 6 sites today was 147, and for salmon parr it was 43.8, really good results, although as noted above we don’t really have any benchmark from the Avon for comparison. The gradient of the Avon is much higher than the Spey and it appears to be almost universally good parr habitat. There are acres of habitat in the Avon similar to that which we surveyed today. We try to select representative habitat; it is clear from todays surveys that the lower Avon is currently supporting a large population of salmon parr.

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