Chabet Burn redd count

The weather today was not the best for redd counting – strong wind/sleet/low light levels etc but Rothes ghillie Robbie Stronach didn’t flinch when I called to ask if he still wanted to go to the Chabet Burn as planned this morning. The Chabet has featured on the blog a couple times before but this was the first time we had counted redds. Robbie knows the burns well so we set off to count the redds in a stretch in the middle/upper reaches of the burn.

We surveyed a 1.5km stretch where the average width was about 3.5m, giving an area of 5250m2. There were redds obvious from the start, mainly sea trout redds we thought, although some were of a size that could have been made by salmon or possibly larger sea trout. Within the survey stretch we recorded 30 redds. This was the minimum count as the conditions were not the best for identifying those redds in deeper or faster water.

Two redds in the Chabet Burn.The water in the Chabet is often dark with peat stain but it is a productive wee burn.

Two redds in the Chabet Burn.The water in the Chabet is often dark with peat stain but it is a productive wee burn.

We didn’t see one fish, dead or alive within the stretch; the fish had spawned and gone. After the count we checked another few hundred metres downstream from our start point. The habitat here was ideal for spawning and the redds here were much more frequent and often larger.

Nice spawning habitat downstream below the track bridge. This looks like a really important spawning area from which many of the fry and parr that populate the lower burn will originate.

Nice spawning habitat downstream below the track bridge. This looks like a really important spawning area from which many of the fry and parr that populate the lower burn will originate.

The dog came with us on this walk and he found one carcase, a hen salmon of about 5lb that had been predated.

Remains of hen grilse. There were some eggs scattered around but not many, perhaps she was partly spent.

Remains of hen grilse. There were some eggs scattered around but not many, perhaps she was partly spent.

The weather was much worse by this time and the burn was rising and colouring but we had a quick look at the lower reaches. The gradient here was higher (beaver proof!) and spawning substrate was at a premium but the fish had utilised little patches of gravel where they occurred. It looked like great parr habitat so next time we are electrofishing in this area we will include a site here.

Higher gradient in the lower reaches. Not so good for spawnign but excellent parr habitat

Higher gradient in the lower reaches. Not so good for spawning but excellent parr habitat

One dead fish was found, a hen sea trout of about 5lb (when fresh run). It had been dead a while but there were no obvious predator marks although it was a few metres away from the burn bank.

Nice sea torut hen of about 5lb on the banks of the Chabet. Sea trout numbers have decreased in recent years but the average size has increased greatly. Fish of this size are not uncommon in the Avon.

Nice sea trout hen of about 5lb on the banks of the Chabet. Sea trout numbers have decreased in recent years but the average size has increased greatly. Fish of this size are not uncommon in the Avon.

The farmer was kind enough to invite us in for a coffee once we had finished, accompanied by some home produced smoked fallow jerky, which was delicious.

These taste good when smoked.

Fallow buck wading the Chabet; an uncommon sight on the Spey but they do taste good when smoked.

It was good to learn from Robbies knowledge of the burn and to get some redd count data on record.  I’m sure in days past there may have been 100 redds in the same bit of the burn but the 30 redds seen today were probably enough to deposit the recommended 7 eggs/m2. One things is for sure. there were an abundance of trout fry during this years electrofishing surveys.

Graph showing trout size distribution derived from electrofishing survey in middle reaches of the Chabet this summer.

Graph showing trout size distribution derived from the electrofishing survey in middle reaches of the Chabet this summer.

 

 

There are 13 comments for this article
  1. ian gordon at 8:44 am

    Brian,

    Thanks for the reply.

    The comments of your uncle which would suggest similar runs of fish to that of today are really interesting; as is the fact you respect greatly those views. At the end of the day, I couldn’t agree more, as with no real “long term” data, such anecdotal evidence as well as a very small survey sample, is all we have. Maybe it would also be an idea to talk with Jimmy Grey, and possibly those two old bailiffs [if they are still with us] Hamish and Innes, who spent their life time walking those burns too, as this would help add to the bigger picture.
    High trout and low salmon fry densities will, I’m sure, be part of the long term interaction between the two species, a trend which over time I’m sure will fascinate those monitoring this burn and also the river in years to come. I’m also sure this type of study will learn us a great deal more about long term fluctuations seen in both populations.

    I’m glad to hear your thoughts on the “hockey stick” as, like you, I have always had serious reservations about such graphs, I see ulterior motives and different agendas based on fear of the unknown; based mainly around poor or inconclusive science.

    I would be extremely grateful for any information which would be relevant to the petition as given what those working on the river have seen over the last couple of years it is plainly clear that nets’ killing 10,000 potential spawning salmon, at this time, is unacceptable, and “for me”, not only the spring stock.

    It would appear from your comments, re Dulnain, as well as that seen in “Spawning escapement” data for the Esk, there is a direct correlation between large numbers of fry, and consequently Parr the following year. Whilst I accept this is a very small data sample, something which, given the complexities of the subject matter is always dangerous to quickly set in stone, it never the less, ties in with the observations of those working on the river over a period of time and as such, although anecdotal, obviously lends more weight to fledgling, but still flimsy science.

    Whilst I accept, a bit like farmers, we ghillies will never be happy and always find something to girn about, when precious little data is available then the views and observations of, I cannot now say myself, but of those working full time on the river is really important, for at this time they are the only accurate adult fish counters we have.

    Thank you for the interesting reply and also the support for the petition. Although I have some issues with incomplete, or, “not an exact science” [which to me has always been a contradiction in terms], I very much understand the value of having as much information as possible.

    I look forward to receiving the information.

    • Brian Shaw Author at 10:34 am

      Hi Ian,

      I will email you the Spey stock assessment report. I have met Jimmy Grey and enjoyed a very informative hour or so with him. He was very welcoming and I must go back and see him again. I have also heard a lot about Hamish and the other bailiffs from the past, I have no doubt they will have some good info about stock abundance, but they were fortunate enough to be around during the peak of the salmon runs.

      There is a correlation between fry and subsequent parr but only up to a certain point (the top of the graph), to the right of that more fry doesn’t mean more parr. Regarding the availability of data the 2013 electrofishing report was approved by the Foundation committee yesterday so I will try and upload it to the website today. It is pretty comprehensive, too much for many I’m sure but the data are all there for those interested.

      I couldn’t possibly comment on whether ghillies are always girning or not!

      Brian

  2. Charlie Herd at 12:49 am

    Brian,

    With respect, I think you are missing my point here. You have produced reliable evidence that this burn has a habitat that in the past has supported the offspring of far more fish than have spawned in it this year. When natural stock levels are historically low are burns like this not obvious places to stock from the hatchery or am I missing the point of the hatchery ? It looks like Ian Gordon is equally perplexed.

    • Brian Shaw Author at 8:29 am

      Charlie, Ian,
      I have a Foundation quarterly meeting this morning but will reply later

      Brian

    • Brian Shaw Author at 9:19 pm

      Hi Charlie,

      I never said that the burn supported the offspring of far more fish? What I did say was that even with reduced numbers of adults there can still be adequate fish spawning in this burn to ensure it is stocked to the hilt with fry (as evidenced by our electrofishing results) the majority of which will die over the course of the winter. My argument is that parr densities will be little different now to that present in the 1940s, although I can’t prove it. Lets say for example that the burn produces 1000 smolts (salmon and trout combined). In the 1940s with 20% survival 200 adult fish returned. Now at 5% survival only 50 return; as long as there are sufficient adults the smolt output can remain reasonably consistent. But if the adult numbers drop below a certain point the smolt output will suffer.

      The point of a hatchery is certainly not to add extra fish into a burn that already supports a very healthy population – that will only damage the existing stocks. This is a pretty fundamental point.

      On that line we were out for dinner with my uncle a few weeks ago and he made the interesting comment that when he looks in the Kylintra Burn in Grantown nowadays he sees the same number of fish that he saw as a boy 60+ years ago. On the other hand he also tells me tales about farmers forking salmon off the redds in places where there are none now! I respect everything he says.

      Brian

  3. ian gordon at 11:12 pm

    Brian,

    Those densities seen elsewhere are indeed varied and as such would suggest even fewer fish than are spawning right now would still be enough to stay above critical point. Do we have any idea what this point is? I use the term “critical point” as I remember James Butler showing us a graph showing what was undoubtedly a downward trend ending in a sharp fall,a bit like good old Al Gore’s hockey stick! He was convinced that if we got to the turn in the stick, it was all over! What you are saying is we’re not anywhere near this, in this burn anyway, things are good. How about the river as a whole? Although I don’t know how you got there, I take the point that “Spring Stocks” are “weak” Both I, and I’m sure the readers of the blog would be really interested in the “Two different stock abundance systems” used to come to that conclusion, could you elaborate a little on those? Over the past few years, personally I would have said the same for both Grilse and Autumn fish,having said that, I’m not on the river as much I once was so maybe this is not the case?

    I don’t agree that there is no need a Biologist Brian, without Scientific evidence and data gleaned from years of duplicate experiment, answering potentially difficult questions can be, well, difficult and misleading; no, we definitely need you mate, without a Biologist all we would have are, well; might’s, could’s and possibly’s. As you observe, this is the language of the scroungers and losers of the past! What we need now are FACTS based around sound good science!

    • Brian Shaw Author at 9:57 pm

      Hi Ian,

      James Butler would have been referring to the stock-recruitment curve see http://www.oceanecology.ca/fisheries.htm (need to scroll down a little). Yes you are right what I am saying is that the number of spawning adults are still to the right of the vertical blue line on the graph in the Chabet Burn. I arrived at that conclusion based on the high densities of fry present. I can’t say what the “critical” number is for that burn, that takes years of study, but it has been produced in many places for both trout and salmon. Based on the area available, habitat quality etc an estimate could be made. I don’t necessarily agree that once stocks fall to the left of the line the species is doomed. Salmon have a great capacity to recover, there are plenty examples of where they have, but the stocks would need to be conserved very carefully.

      I am not saying the whole river is good, in fact some of the fry densities suggest that the number of spawners in areas are fluctuating above and below the “critical point”. Take the Suspension Bridge site in the upper Dulnain for example. Last year we found that the fry density was in the good category, unusually good for that site. This year we found the parr density was also in the good category, the best for years. This site is on the margins on the range of salmon in the Spey and the numbers of spawning fish arriving that far upstream will vary considerably from year to year according to the strength of the run, flows, water temperatues, exploitation etc. My thoughts are that the good fry densities observed there in 2012 were on the back of the big run of two sea winter fish in 2011; a run that provided enough fish to penetrate far into the tributaries in numbers. This year the fry densities at that site were down to the usual low levels again, but there wasn’t the same run of fish in 2012.

      This year we found good fry numbers throughout the mainstem (below Spey Dam) and main tributaries, but not to the same extent in the more marginal areas. My thoughts on this are that the eggs in the spawning gravel experienced good incubation conditions with good survival to the fry stage. I am confident that again this year the core salmon habitat areas in the Spey are well stocked with fry, and parr. Densities in the marginal habitat will always fluctuate I suppose.

      I am not to going to argue with your assessment of the adult stocks Ian; you will know much better than me, I tend to concentrate more at the juvenile end. The spring stock assessments I mentioned were a) the SAC site condition monitoring report for salmon 2011 and b) http://www.scotland.gov.uk/Uploads/Documents/SFRR_66.pdf page 23. Unfortunately the SAC site condition monitoring report for salmon has not yet been published but I have the assessment for the Spey which I can email to you if required. These documents may be of relevance for your mixed stock netting petition. By the way I would be delighted to promote your petition here when it is ready to launch.

      Brian

  4. ian gordon at 1:51 pm

    Brian,

    I’m kinda with Charlie on this one. One question I have is – How much below the 7 eggs/per m2, in your opinion, would signal a problem? Or, put another way, how many redds are enough to stock the burn? I’m interested as Im not, and have never been confident in those figures.
    Also, I’m interested, as I’m sure will many readers be in what Robbie had to say about the salmon / sea trout ratio here in the past.
    The suggestion is – Very few fish are required to keep the river stocked to an “acceptable” level something which, if true makes me think, why am I returning all my fish if, as suggested above, they are surplus to requirement?

    • Brian Shaw Author at 9:14 pm

      I too share your reservations about the use of conservation limits and egg targets. Whilst a target figure for a catchment can be produced the distibution of spawning is rarely consistent throughout therefore some areas will be well above whith others well below. If for the time being we accept that certain organisations require targets how does the Scottish target compare with that set in other countries? Some examples are Canada = 2.4/m2, Ireland 3.5 to 7/m2, England & Wales = 0.7 to 4.0/m2 and Norway 1 to 6/m2. We appear to have a high threshold and within Scotland the Moray Firth has the highest target.

      We did two surveys in the Chabet Burn this summer (the water level was too high to complete the planned lower site) and the minimum average density of trout fry was 230+/100m2 or 2.3+/m2, with the density in both sites practically identical. You may not accept it but imho and in comparison with the SFCC classification, that is a very good density of trout fry, not quite walking across their backs territory but getting there. There will be a huge mortality of fry in that burn over the course of the winter as it is stocked to surplus to a massive extent. I don’t know how many redds there were in that stretch last winter but my hunch is that it would be similar to what we saw this year. If there were 7 trout eggs/m2 last winter then the survival to fry in august appears to be in the order of 30%, a testament to the productivity of that little burn.

      My understanding is that the egg depostion target was based on achieving the maximum sustainable yield in the stock recruitment curve for that river/area/country. Any reduction in egg deposition, on average across the catchment would therefore potentially result in a reduced crop, although the numbers could probably drop quite a bit before there was a noticeable difference. We found a redd on average every 50m in the Chabet Burn, if there was one every 100m it might still be enough to stock it fully, but I wouldn’t like to see less. There are similar burns in the catchment where you have to walk a lot further than 100m to see a redd, and they certainly won’t be fully stocked. On the other hand today I watched fish spawning in the Spey mainstem in an area where there was an abundance of redds, one after the other. I first saw fish spawning there two weeks ago and they have been at it ever since; the egg deposition in that particluar area must be very high but there is a huge area of fry/parr habitat to stock.

      Your second point – I’m sure a man as well connected as yourself already knows Robbie’s thoughts on the salmon/sea trout ratio but for those who don’t. We did our redd count upstream of where Robbie thought the main salmon spawning area used to be and on the day the burn was rising and colouring too fast to see what was going on in the lower reaches. My impression from Robbie was that he didn’t expect to see that many salmon in the upper reaches where we did our count. Robbie did talk about his brother collecting 2 fertiliser bags of salmon kelts for fox bait one day in the lower reaches of the burn. Two fertiliser bags of salmon kelts is probably around 20 fish, quite a lot in comparison to the number of dead fish you would see nowadays, but we are not experiencing the same marine survival now. We often find inceasing proportions of juvenile salmon in the lower reaches of burns and I’m sure it would be the same in the Chabet.

      Your third point – conservation of the stock should be targetted where it is needed, for example the recommendation on the Tweed that all spring fish are returned but that you can do what you like with the autumn run. So if you kill a fish and it was destined to spawn below Loch an Duin in the upper Tromie, then you have undoubtedly hurt that stock; a stock on the very margins of Spey salmon penetration. If you killed one destined to spawn in the mainstem site mentioned above it would have next to no impact on the local stock abundance. If the stocks are as genetically isolated as many suggest then the impact of catch and release depends on where that particular stock is on the stock recruitment curve or egg deposition target. Two different stock abundance systems used to categorise the Spey salmon stock recently concluded that the spring salmon run on the Spey is currently weak, but then you don’t need to be a biologist, or even a scrounging loser, to work that out – do you.

  5. Charlie Herd at 11:52 pm

    Hi Brian,

    Have we ever stocked this burn? From what you say it has lots of spare capacity.

    Charlie.

    • Brian Shaw Author at 9:13 am

      Hi Charlie,

      From the records it appears to have been stocked once with sea trout – you may well ask why?? However I think you miss the main point about the current spawning in the burn – there is no spare capacity. Even with the current lower number of adult returning there are enough spawning in the Chabet Burn to ensure it is fully stocked. Look at the number of trout fry in the graph; it was absolutely stuffed. I didn’t show the salmon, they were much less numerous but still present in good numbers. At the upper site it was trout only, again in very good densities and I’m sure it was always thus.

      Best regards

      Brian

      • Charlie Herd at 11:33 am

        Obviously this is a prolific burn. I read your comment that in the past there may have been 100 redds as against 30 now to indicate that there may be spare capacity.

        Charlie.

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