Dulnain salmon fry index surveys 2018

On Monday and Tuesday this week we completed all but two of the River Dulnain mainstem surveys. The remaining sites are in the upper reaches and each site entails a long drive in, these will be done as soon as an opportunity arises. Conditions were ideal, the river rose a couple inches at the weekend and the temperatures had cooled considerably from the recent highs.

The overall results were excellent with the fry counts almost double those recorded in 2015. The parr counts were much higher than in 2015, although those figures would have been affected by the ex-Hurricane Bertha spate (remember this https://www.youtube.com/watch?v=yWS6ghvapuA )

River Dulnain 2012/2015/2018 mainstem salmon fry index surveys.

Carrie and Euan processing the catch at site TSD02, which was immediately upstream of the old railway line. Habitat quality here is great; there is a big long riffle upstream, which must support many hundreds of parr.

We recorded considerable variation in the size distribution from site to site. The size distribution graphs from a selection of the sites are shown below (ordered in an upstream direction). The horizontal scale gives fish size in mm but note that the vertical scale varies according to the numbers present at each site. Bear in mind that these surveys consist of a standard 3 minute survey using a banner net to capture the fish. This methodology has been consistent since 2012.

Fry size varied a lot, and not always smaller with increasing altitude. Competition also has a big influence in this regard with the average size at the Duthil site (348 fry) being smaller than those at the Lochanhully site (85 fry). Upstream of Carrbridge the average size dropped e.g. at Feith Mhor and Dalnahaitnach. I suspect the enrichment entering the river at Carrbridge is an important factor in the increased average size, and biomass, of the juvenile stock.

The only other tributary location when the fry counts have entered the blue zone (more than 100 per minute) was in the Fiddich (in 2014 and 2017). The Dulnain, however, stands alone for a parr count in the blue zone (more than 100 in the three minute survey). The 125 parr caught in three minutes at the Lochanhully site was exceptional, the best we have recorded in the Spey catchment. Only once before have more than 100 parr been captured in one of these surveys; that was in the Spey at Aberlour in 2014. All the 2018 sites are being recorded on Gopro so check this link for an edited video of the survey Lochanhully.

Carrie releasing the catch at the Lochanhully site. This photo doesn’t do the site credit, the lower reaches comprised a superb riffle, full of small boulders providing an abundance of hiding places for fish.

Numbers are not everything when it comes to parr however. It is considered that a parr needs to be 90mm in lenght at the end of the summer to smolt the following year. From the size distributions I can see that at the lower site TSD02 90% of the 52 parr present will be large enough to smolt in 2019 (if they survive), only 16% at the Dalnahaitnach site are likely to make that threshold. This is a good thing as it spreads the smolt output from the strong 2017 cohort over more than one year.

A selection of fry and parr from TSD34. There were fry and one and two year old parr present

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A lean salmon parr of 78mm, this may need to remain until 2020 to smolt, it might not be big enough to do so in 2019.

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The low water experienced in 2018 will inevitably result in some contraction of the juvenile stock in 2018, and this will need to be factored in, but perhaps not that significantly in the Dulnain. Water levels has increased from what I would call very low to low before most of these surveys were completed. The levels did not appear too dissimilar to other low water years in the Dulnain. We also watch river temperatures closely (they are measured at each site in advance) and we do not survey if the temperature is above 20oC. Consequently we did no surveying last Thursday and Friday at all due to the high temperatures forecast.

We plan to do the same style surveys for the Nethy and Druie tomorrow, it will be interesting to see if the Dulnain high counts are repeated. Most of the Spey mainstem surveys have already been completed, but not all. These results will be published once the surveys have all been completed.

All in all these results are very encouraging.

Authored by: Brian Shaw

There are 8 comments for this article
  1. Callum Robertson at 11:03 am

    Surely we do not need more research and statistics? We need Spey Fishery Board resources allocated to projects that will provide meaningful improvement to catches. Common sense could work out that very low water will increase the density of fry and parr counts. These statistics are only relevant to that day.

    Resources should be re-allocated to the excellent work that Jimmy does at the Sandbank Hatchery.

  2. Andrew presley at 9:58 pm

    So all seems very good in river system , a very healthy river it seems.
    So my question which seems to be related to a lot of river systems in Scotland. Why don’t salmon return if good numbers are going to sea?

    • Brian Shaw Author at 8:42 am

      Hi Andrew, It is good to see that the juvenile population remains robust despite reducing numbers of adults. The numbers of adults returning from the sea has always been a function of the number of smolts leaving and marine survival. The smolt production of the Spey varies, a lot. Right now it has the potential to be very good in 2019 (no extreme spates please!). Marine survival has been declining, and possibly more unpredictable. I think that cyclical factors are one of the most important but there is also a downwards decline. Catches will improve although not likely to reach past peaks.
      Theories abound as to why marine survival is in decline; northwards movement of the plankton, sea lice from aquaculture, overfishing, underfishing, nearshore survival, too many mackerel etc. We will be involved with the AST Missing Salmon project (http://www.atlanticsalmontrust.org/missing-salmon-project-your-questions-answered/) next year which might shed some light on inshore issues.
      Anyway must go and get ready for today’s surveys, we need to get out before it warms up too much. Thanks for your interest, Brian

      • James McCaig at 8:37 am

        Hi Andrew,
        AS a riparian owner at Easter Elchies I would like to point out that your question has been answered by Brian Shaw in a form which toes the Spey Board’s line and depends on making an interpretation of the data that something can be made out of nothing. A common sense observation is that small numbers of salmon lay small numbers of eggs and that is represented by small numbers of smolts going to sea and unsurprisingly small numbers of mature fish returning to continue the cycle. However, something needs to be done to reverse the decline and the ‘wilding’ faction controlling the Spey Board refuse to address the problem.
        Regards Jim McCaig

        • Ian Gordon at 6:25 pm

          Hi Jim,

          Almost every ghillie who has been around on the river long enough to remember the good times, A time when both adult and juvenile fish were so plentiful and we believed what our eyes told us. It would seem that today, those same eyes cannot be trusted to provide any information that fails to tie in with current scientific thinking.
          We are told the river is in good health, however, as you rightly point out, how can that actually be? I heard someone quote a figure of 100,000 fish running, or present in our river, another was 50K, the answer is, no one really knows but as has always been the case, the people with the “best idea” are those spending the most time on the river. Especially the ones working on one specific beat. My guess, based on what I and others have told me this year, would be less than 2000! Maybe even as little as 1000. Simple maths would let everyone know the high figures above are stupidly wrong and given there is a correlation/link between numbers of adult and juvenile fish, then the number of juveniles in the river simply must be lower than before. The notion that small numbers of fish can properly stock the whole of the river Spey, sending enough juveniles to the sea, well, its fantasy. Certainly, it’s what my, and the eyes of nearly every ghillie old enough to remember are telling us right now.
          Anecdotal!? Does it really mean? Should we not use our eyes to process information anymore? Would it be anecdotal for me to say one ball is black and the other white? Of course, it wouldn’t. Then why when processing this information are all the “facts” not taken into account. The facts that we once caught many more Parr with rod and line in times of low water flow, or that we physically saw more shoals of fry? Why is this information not taken into account? The reason is, all of this is driven by people with different agendas. We [most anglers] want to see hatcheries on the river and the scientific community don’t. Unfortunately, the latter will always win the day. Just as we all know with regard adult fish, I know for a fact there are far fewer juvenile fish in this river than at the time when all fish were plentiful. I remember making the observations in the mid-1990s, only to be told by the then chairman of the board – “What are you talking about Ian”? “We’re still catching 10,000 fish and we have done for the past 50 years”! My answer was, you won’t be in the near future! The last time we caught 10k on the Spey the total run would have numbered 20k max. Over the past few years, when the rod caught figure has averaged 6k, In all probability, the total run will have been less than10k. This year, until this point we’d lucky if that figure is 2k. Totally shocking, and what do we intend to do about it? Will those in charge finally accept they may have got things wrong and those on the ground have been right all along? When I got back to find the board had made the decision not to accept the help of Tulchan and others, given and understanding the seriousness of the situation, I have to say, I was totally flabbergasted. I’m afraid we are well down the slippery slope which is getting more greasy by the minute.

          • Arnot McWhnnie at 9:40 am

            I’m a 75-year-old journalist who has been seriously fishing for salmon since the early 60s, and has seen the good days when there were terrific runs with plenty of salmon to satisfy commercial nets, anglers and predators. We witnessed spring runs diminishing, then the grilse runs, and over the last 10 years or maybe a bit more, the autumn runs. Now the salmon runs have literally fallen off a cliff. Obviously something is happening at sea with global warming and over fishing of krill, sand eels, and capelin which feed smolts when they migrate to sea. Closer to home predators such as saw billed ducks, seals, dolphins, and otters are feeding on diminishing stocks of salmon. The fish farm sea lice and disease problem is also a major causation. I ask myself what is being done? I think the answer is not a lot. I am now adding fishery biologists to the list of the many dangers to salmon. Oh yes, they are doing research and river surveys to tell us what we already know. Salmon need to be helped. What is taken out needs to be replaced, and fishery boards are just playing at that. I agree with Jim McCaig that fewer returning salmon result in fewer eggs, fewer smolts, and even fewer mature salmon to complete the cycle. The other inevitability is fewer anglers and with their non appearance, a financial loss to our local communities and the he resultant loss of jobs. I was therefore aghast when I learned that the Spey Board had vetoed an offer by the owners of Tulchan to produce smolts free gratis to help the river. By the same token, on the Tay, the board appears to have turned down pleas to reinstate the famous Fishponds at Lower Scone where P.D. Malloch 100 years ago reared smolts. Surely those charged with the wellbeing of our rivers should be trying every trick in the book. This weekend I’m off to Iceland for my 10th visit to fish the East Ranga river which is dependent on smolt ranching because there is no natural reproduction due to volcanic ash which smothers any salmon eggs. Not long ago two guides fishing for brood stock had 160 salmon in nine days. Currently the river is producing 100 fish a day for 18 rods and the catches are getting better and better every day that passes. On a day last week 149 were landed. Attention marine biologists, DOES THAT NOT TELL YOU A STORY!!! Get the finger out and at least be seen to be doing something. If you don’t try you don’t get.

          • Callum Robertson at 10:42 am

            Totally agree Ian. The Spey Fishery Board should be listening to people like yourself who have vast knowledge of the river. Why would they ignore the ghillies? The people who know the river the best. Crazy decision not to accept the Tulchan offer. The board needs a total shake up – more resources to hatcheries and less to the endless research and statistics. They are presiding over a horrific period of downward catches and should be far more accountable. They need to cut their cloth.
            Time for change.

          • Brian Shaw Author at 7:21 pm

            Whilst the Spey Fishery Board welcomes constructive dialogue on the Speyblog these comments should be restricted to the content of the blog post. Some of the comments made on this post in recent days have not fulfilled this requirement. Comments made to date have been approved but this is not a forum and further comments on this post will now be closed.

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