Middle Dulnain parr surveys

Much concern has been expressed about the juvenile salmon densities in the middle reaches of the Dulnain, one of the Spey’s most significant tributaries. Our earlier salmon fry index surveys found that salmon fry were present throughout the Dulnain although numbers were much higher in the lower reaches.  Today we completed single run surveys at three locations at Balnain, Inverlaidnan and Dalnahaitnach in order to try and quantify the parr density. I joined the team just before they started at the Inverlaidnan site. The Dulnain, even this high up is still a large river and the mean width was over 15m. This is wider than recommended in the SFCC protocol but a one run survey was only ever going to provide an indication of the minimum density present.

The site at Inverlaidnan was called D21. The photo below shows the type of habitat present. There was a high percentage of boulder and cobble providing loads of cover.

Inverlaidnan electrofishing site D21

We surveyed an area of over 300m2 and captured 94 salmon fry and 34 salmon parr along with a few trout. Calculated densities will be shown below.

Catch from site D21

After processing the catch we moved up to the end of the road at Dalnahaitnach where we completed another survey site just upstream of the remains of the old bridge. It can be seen from the photo below that the habitat at the site was good for parr. There is a vast area of similar habitat in the upper and middle Dulnain. Our site started above the upper riffle in the photo.

Site D22 Dalnahaitnach

Quite a lot of fish were caught in the site which was 19m long. Salmon were dominant with only 1 or 2 trout present. Below are a few photos of the fish processing.

Processing catch Dalnahaitnach

Salmon fry were quite small at this site, although plentiful

Measuring salmon parr at Dalnahaitnach site

 

Recording fish sizes

 

The big pectoral fins make identification of juvenile salmon easy, even from this bucket shot. There are three year classes present.

Back in the office densities of both salmon and trout fry were calculated. I like to use the SFCC national classification system to classify site results. This system is based on over 1600 results from across the country.  The table is colour coded to make results more visual.

Scottish Fisheries Coordination Centre national classification scheme

A salmon fry density greater than 42.1/100m2 is in the top 20% of Scottish results ( A class or Excellent) according to the SFCC classification and between 20.3 and 42.1/100m2 is in the second 20% band (B class or Good). For salmon parr anything between 9.1 and 15.8/100m2 is B class.  It can be seen then that the juvenile salmon densities at the three sites are all in the moderate to excellent category. Full details of the classification scheme can be found here (Godfrey, 2005).

Dulnain densities

The average size of the fry and parr decreased with altitude. The Dulnain is no rich limestone stream and the invertebrate population is relatively sparse but the fish that live there are adapted and grow accordingly.

Average sizes at each of the Dulnain sites

All in all it was yet another fascinating day on the river. The results indicate that the Dulnain supports a moderate to excellent density of juvenile salmon, and confirm its status as a significant smolt producer.

If anyone wants to joins us on an electrofishing trip please get in touch, assistance is always welcome.

There are 2 comments for this article
  1. Mel McDonald at 4:05 pm

    Hi Brian

    Good to see such healthy numbers. I understand the Dulnain was stocked last year with 0+ parr as part of the 2011 stocking programme. Is there any way that you can identify whether some of the parr you found resulted from that stocking thus allowing you to record good densities ?

    • Brian Shaw Author at 7:18 pm

      Hi Mel,

      The quick answer is no unless we do some genetic analysis.

      My understanding is that the middle reaches of the Dulnain were stocked in 2010 with fed fry of Dulnain origin in June. These fish would now be 2+. We found a few 2+ parr in the samples but in very low numbers compared to the 0+ and 1+.

      In 2011 some of the Dulnain burns were stocked with 0+ parr from the Tulchan hatchery in late summer/early autumn. As far as I can establish they were stocked into the Allt Fionnaich and tributaries and the upper reaches of the Batten Burn. The Allt Fionnaich is 6-7km upstream of our upper monitoring site whilst the Batten Burn is a long way downstream. Whilst it is possible that the stocking in Allt Fionnaich could have contributed to the results at our survey sites at Dalnahaitnach and Inverlaidnan it is highly unlikely given the distance and other factors.

      The abundant fry and 1+ parr numbers present throughout the Dulnain this year, the excellence of the spawning and nursery habitat all suggest that the Dulnain should be self-sustaining. Indeed in reviewing the past electrofishing results from a site close to Dalnahaitnach I can see that this has been the case on each occassion parr surveys were completed (see below). I can’t post a coloured table whilst replying to a comment but I have added the classification after the density figure. You’ll see that it has been variable but with moderate densities in the last survey at the site in 2009. The earlier surveys in the series at the site were a lot better. We found better results at the nearby site this year. Maybe the Dulnain juvenile population has been through a dip?

      Site D13 – Dulnain, downstream Dalnahainach
      Date Salmon fry Salmon parr
      14/09/2009 12.8 Moderate 7.8 Moderate
      01/09/2004 4.9 Poor 4.9 Poor
      07/08/2003 27.1 Good 5.0 Poor
      07/08/1998 44.9 Excellent 13.0 Good
      02/09/1997 24.9 Good 11.0 Good

      There seems to be a perplexing lack of faith in the ability of the Spey salmon to reproduce naturally? I left those Dulnain survey sites the other day with not a shadow of doubt in my mind that the fish we saw were of wild origin. There is obviously a job to be done to persuade or show others that was indeed the case.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.