Avon mainstem sampling day 4

The last four mainstem timed sites on the Avon were completed today. The sites were all up near Faindouran Bothy with the upper site situated at over 600m (2000′) altitude. Salmon fry and parr numbers declined at each site with no salmon fry found at the upper site.

The uppermost mainstem Avon site. No salmon fry were found here. A solitary salmon parr and three trout were found. This must be very close to the upper limit of salmon on the Avon.

The uppermost mainstem Avon site. No salmon fry were found here. A solitary salmon parr and three trout were found. This must be very close to the upper limit of salmon on the Avon.

We didn’t make Loch Avon today, that will have to wait for another day but our understanding of the Avon salmon population has increased greatly over the course of the last week.

Avon salmon fry numbers per minute for all Avon mainstem sites. Fry were found at all but the upper site although in in decreasing numbers

Avon salmon fry numbers per minute for all Avon mainstem sites. Fry were found at all but the upper site although in decreasing numbers.

Avon mainstem sites salmon parr per minute. Parr were found at all site although there was a general decline as we went upstream.

Avon mainstem sites salmon parr per minute. Parr were found at all sites although there was a general decline as we went upstream.

Concerned about how to place this years timed electrofishing survey, and the current Avon fish population in context, we also did a quantitative survey at a long established site located 42.5km from the confluence with the Spey just upstream of where the Allt Loin Bheag joins the Avon. This site has a long history of surveys having been surveyed 13 times since 1991. The more recent site records are logged in the SFCC database but there were also a number of old paper records available. I have summarised all records from this site in the table below.

Avon site SA85 electrofishing records.

Avon site SA85 electrofishing records, expressed as fish densities per 100m2. As always green means good fish densities with lower densities in amber or red. The colour coding is based on the SFCC Moray Firth regional classification corrected for stream width.

The results from this site have been variable although salmon fry were present every survey (1992 survey was completed in May too early in the year for the fry to have emerged). The site is shown in the photo below.

Avon site SA85. The site is a half width side surveyed from the bank out to midstream in line with two large boulders. This type of survey will provide a bit more viarability than a site that extends from bank to bank but at least we have some data to compare over a long time series.

Avon site SA85. The site is a half width side surveyed from the bank out to midstream in line with two large boulders. This type of survey will provide a bit more variability than a site that extends from bank to bank but at least we have some data to compare over a long time series.

The results from 2003 in the table above were exceptionally good although I noted when reviewing the records that the site area fished was about half that surveyed in most other years. As the boundaries of this site are well established in the comprehensive site photo files it is difficult to see how the area fished could have been so small, either the river was exceptionally low or there may have been an error in the recording. In spite of that the salmon fry numbers recorded during todays survey were the second best in the series. The salmon parr density this year was the third best. The long site history covers periods when Spey salmon catches have varied considerably but with the exception of the 2003 results the current juvenile salmon densities in the upper Avon appear to be quite good by comparison to the site history.

We had a 4 person team today which did add a couple fish to the catch but we are using the same style of banner net as has always been used. The electrofishing equipment is new and we were using 450v but high voltage settings have always been used in the upper Avon, hopefully the methodology deployed today is comparable with that used in the past.

So that is the Avon mainstem survey over, we still have many tributary sites to do but it was good to complete the mainstem surveys within a short timeframe and when water levels were lowish.

On the riverbank at the uppermost site today we found some camping debris; a whistle, a cutlery set and a neat little tin containing feminine hygiene products. Two of the products were missing but there was still six left in the tin. What a surreal way to finish the Avon mainstem survey – at our last site, at 2000′ in the Cairngorm mountains we found more tampons than fish!

Lifejacket whistle and neat little travel pack of tampons, found on the riverbank in the upper Avon.

Camping debris found on the riverbank in the upper Avon.

 

 

 

 

 

 

 

There are 3 comments for this article
  1. Jamie Urquhart at 5:49 pm

    Tarpon in the Spey !!!
    Never mind salmon that’s a fish worth catching.
    Cheers Jamie

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