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SOS,
am I right in thinking that the Girnock's figures are more in decline he Girnoch used to feature quite
My point was that without these tracking studies and knowing the migration routes it would be very difficult to go the authorities and say we THINK that the Salmon smolts are dying because of XYZ, where as if we had the data then it would be easier to argue the point.

I have just been looking at the smolt output and adult return rates for the Girnock burn and although there are or can be big variations year by year there is a downward trend in both smolts and returners. With adult female return rate at 1% and assuming the same rate for males that would mean that you need an extra 200 smolts to produce one pair of Salmon, if you increased the survival rate of the smolts (2000 conservative) that leave the burn by the same 2% that gives you 20 pairs of Salmon.
Although survival rates/returns will depend on the length of river migration, as CharlieH alluded to it would need a helluva lot of extra smolts to make any significant difference to the total run of Salmon on the Dee. But all improvements to habitat and food availability should also be done.
If tracking Salmon smolts in river or at sea can lead to an increase of just 1% or 2% survival rate that would make a huge difference.

file:///home/chronos/u-7465ee8fa961ef8c625d55c4861bf467a0d3c824/MyFiles/Downloads/girnock-baddock-fish-traps%20(2).pd
 

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I seem to remember that in storm frank year, the par numbers were reduced, but because of this the smolts were bigger that summer.
So where is the increase of returners?.
It is my opinion that to increase the amount of returners the output has to also increase, but because the input and output are in reverse the numbers will continue to decline no matter the size of the smolts.
 

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SOS,
your first statement is entirely correct: the key to success is the maximisation of smolt output from rivers, because once they're out at sea there's nothing much we can do but sit and wait for them to return. So that requires the largest possible suitable spawning areas and fry/parr nurseries with ample food supplies. Any interruption of the critical inputs - gravel, invertebrates etc - will have serious impacts on smolt production.
If by intervening in the headwaters we can increase egg to smolt survival from 2% to 3%, then on average each mature hen salmon will be sending an additional 60 smolts into the migration process (i.e. from 120 to 180, based on 6,000 eggs). With a sea survival rate of 3-4%, that brings 5-7 back per spawning hen.
Of course the maths aren't that simple, because there's no 'average' hen. Most produce few or no surviving smolts, while a few deliver lots: it's a skewed distribution. Nevertheless it's good enough to demonstrate the advantage to maximising output.
It stands to reason that we should look out for sources of exceptional losses at sea, and wherever possible seek to eliminate them, but we shouldn't allow that hunt to divert attention and resources from the vital work in the headwaters.
 

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Discussion Starter · #46 ·
I've said before on the forum about the massive flood my river had in 2017 where homes and businesses were flooded and we lost bridges and weirs that had stood for well over a century. Because of the localised nature of the intense rain, there were only 2 rivers that suffered from the really bad floods.

After the flood, the fields were littered with fish at every stage of the life cycle. It was sickening and we really feared the worst.

However, the entire river became one massive spawning bed with the big boulders washed away and almost the entire river was left with lovely gravel.

We caught fish every year after the flood and last year, three years since the flood, our counter recorded its highest numbers in years. In fact, I don't think any other river on the entire Foyle system, of around 20 rivers, recorded more than the Faughan.

Whether this was due to the gravel or easier access to the upper reaches with the Weir washed away, we really don't know. Maybe it had something to do with far less juveniles competing for foods after the flood and being able to grow bigger and stronger? We really don't know that either. However, last year was certainly an improvement, numbers wise, than many years in the past.
 

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So where is the increase of returners?.
It is my opinion that to increase the amount of returners the output has to also increase, but because the input and output are in reverse the numbers will continue to decline no matter the size of the smolts.
there wasnt an increase in numbers, but there also wasnt the huge anticipated decrease in numbers.
It isnt either or!
You need plenty smolts, but the quality also makes a big difference.
 

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I don't want to be a bore because yes it would be great to be able to magically increase marine survival but the adult returners to Girnock are only in small part derived from smolt emigrants and no one knows how many smolts return to other part of the catchment. Therefore there is no way anyone can claim it takes 100 smolts out for 1 adult.

I think it would fantastic to have a smoking gun but there are many easier and cheaper ways to get evidence. Tag 2 large batches of smolts from a river like the Laxford. Release one batch in the river and the other batch at sea. Count relative returns and repeat for 5 to 10 years. Do the same concurrently with a river without a salmon farm in the estuary and that should give you some pretty good evidence of the impact of salmon farming in the estuary.
Yes you could do that and use a helicopter or barge to bring smolts far out to sea to avoid potential estuarine/bay mortality and compare to river run smolts. This was an experiment completed many times in different rivers and in different countries - all with the same result. Smolts brought out to sea simply strayed all over the place on their return. Their return to their natal river also slowed making them more susceptible to near shore predation. To run such an experiment on wild salmon today would (or should) be impossible in terms of fish welfare. But yes you are right scientists should think outside the box as with this tracking programme. Looks like there are zones in the marine that are critical to Salmo salar survival so let's pin those down.
 

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I've said before on the forum about the massive flood my river had in 2017 where homes and businesses were flooded and we lost bridges and weirs that had stood for well over a century. Because of the localised nature of the intense rain, there were only 2 rivers that suffered from the really bad floods.

After the flood, the fields were littered with fish at every stage of the life cycle. It was sickening and we really feared the worst.

However, the entire river became one massive spawning bed with the big boulders washed away and almost the entire river was left with lovely gravel.

We caught fish every year after the flood and last year, three years since the flood, our counter recorded its highest numbers in years. In fact, I don't think any other river on the entire Foyle system, of around 20 rivers, recorded more than the Faughan.

Whether this was due to the gravel or easier access to the upper reaches with the Weir washed away, we really don't know. Maybe it had something to do with far less juveniles competing for foods after the flood and being able to grow bigger and stronger? We really don't know that either. However, last year was certainly an improvement, numbers wise, than many years in the past.
It was certainly an improvement, Jockie, and the Faughan Counter originally recorded a run of over six thousand fish at the end of 2020. This counter always gives the bare minimum of fish that run through.
However, earlier this year the Loughs Agency suddenly reduced this number by over two thousand fish.
Why? I have never seen any published scientific reason.

And this year the run is only sixty-nine fish - well according to the counter, that is.
The date of the last reading is given as 21st May, 2021.
So the whole of the summer run, and part of the autumn run, is not recorded.

Personally, I believe those who say that the river is "stuffed with fish".
And long may it continue.
 

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Discussion Starter · #50 ·
It was certainly an improvement, Jockie, and the Faughan Counter originally recorded a run of over six thousand fish at the end of 2020. This counter always gives the bare minimum of fish that run through.
However, earlier this year the Loughs Agency suddenly reduced this number by over two thousand fish.
Why? I have never seen any published scientific reason.

And this year the run is only sixty-nine fish - well according to the counter, that is.
The date of the last reading is given as 21st May, 2021.
So the whole of the summer run, and part of the autumn run, is not recorded.

Personally, I believe those who say that the river is "stuffed with fish".
And long may it continue.
I saw somewhere that it was reduced to by 2000 but even 4000+ is some improvement from when we were scraping over 1000 to 1500 a season.

Long may it continue is right! ?
 

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I think most of us would agree that there are less Salmon in our rivers now than there were 10+ years ago, so if there were more Salmon then that would mean more eggs, fry, parr, and smolts sharing the food supply.
UNLESS the fact there were more dead kelts that contributed to the food supply for the younger generations and the bigger parr and smolts having more eggs and fry to eat.
Over the past few years the Dee trust have eased or removed many barriers and obstacles that should allow fish into areas of habitat that they could not get to in the past which should have helped to increase numbers but the numbers still look like they are in decline.

Could it be that the importance of dead kelts to a river has been underestimated regarding food supply, less Salmon= less dead kelts, less eggs, fry, parr, and smolts, while more Salmon means more dead kelts which in turn would produce more eggs,fry, parr and smolts and therefor more food.
Maybe the Dee trust were not far off by putting deer legs into the river Gairn, maybe by introducing dead animals and fish heads guts etc to suppliment the food supply might help reverse the downward trend and produce more smolts and therefor more Salmon and more dead kelts.
 

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Discussion Starter · #52 ·
I think most of us would agree that there are less Salmon in our rivers now than there were 10+ years ago, so if there were more Salmon then that would mean more eggs, fry, parr, and smolts sharing the food supply.
UNLESS the fact there were more dead kelts that contributed to the food supply for the younger generations and the bigger parr and smolts having more eggs and fry to eat.
Over the past few years the Dee trust have eased or removed many barriers and obstacles that should allow fish into areas of habitat that they could not get to in the past which should have helped to increase numbers but the numbers still look like they are in decline.

Could it be that the importance of dead kelts to a river has been underestimated regarding food supply, less Salmon= less dead kelts, less eggs, fry, parr, and smolts, while more Salmon means more dead kelts which in turn would produce more eggs,fry, parr and smolts and therefor more food.
Maybe the Dee trust were not far off by putting deer legs into the river Gairn, maybe by introducing dead animals and fish heads guts etc to suppliment the food supply might help reverse the downward trend and produce more smolts and therefor more Salmon and more dead kelts.
I saw them doing that on countryfile a while ago and had completely forgotten about it till you mentioned it now. I suppose it will take a few years to see if the carcasses in the water can help.

I do think that farming and environmental factors are different too. There was far less silage, slurry, fertilisers etc from farming and far less sewage and prescription drugs from housing.

There was definitely far more insect life on my river years ago. I can remember one pool in particular that the flies were thick in. Swirling around the surface of the river like a fog and the trout and juveniles boiling beneath them feasting on them. It's very different now.

There was far less algal growth too between spate as there was far more water in the river.

I feel that our rivers were far better equipped to handle more juveniles in the past.
 

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I feel that our rivers were far better equipped to handle more juveniles in the past.
I personally think that your point highlights a critical factor in the relative decline in numbers of returning adults.

Where nursery habitat remains at least relatively untouched, Smolt numbers seem relatively stable (Girnock & Baddoch). Where an entire system is relatively untouched, returning adult numbers seem relatively stable (The North Coast of Scotland).

The middle reaches of most rivers seem to be in a worse state due to Agriculture and / or sewage and we have so many others where the long term effects of Hydro and drainage are having a serious impact on the headwaters too.

The cumulative effect of this has to be less Smolts and less healthy Smolts heading to sea.
 

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Discussion Starter · #54 ·
I personally think that your point highlights a critical factor in the relative decline in numbers of returning adults.

Where nursery habitat remains at least relatively untouched, Smolt numbers seem relatively stable (Girnock & Baddoch). Where an entire system is relatively untouched, returning adult numbers seem relatively stable (The North Coast of Scotland).

The middle reaches of most rivers seem to be in a worse state due to Agriculture and / or sewage and we have so many others where the long term effects of Hydro and drainage are having a serious impact on the headwaters too.

The cumulative effect of this has to be less Smolts and less healthy Smolts heading to sea.
I really didn't want to 'like' that post as it sadly reflects the state that a lot of our rivers find themselves in. 100% correct but just so very sad. ?
 

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I personally think that your point highlights a critical factor in the relative decline in numbers of returning adults.

Where nursery habitat remains at least relatively untouched, Smolt numbers seem relatively stable (Girnock & Baddoch). Where an entire system is relatively untouched, returning adult numbers seem relatively stable (The North Coast of Scotland).

The middle reaches of most rivers seem to be in a worse state due to Agriculture and / or sewage and we have so many others where the long term effects of Hydro and drainage are having a serious impact on the headwaters too.

The cumulative effect of this has to be less Smolts and less healthy Smolts heading to sea.
The other factor you need to take into account is abstraction, which is insidious, slow-acting but exponentially cumulative in its effects in the long term. You only have to look at the MOD's archive of aerial photography of the Spey valley since 1940 to see a good example of the effects of damming headwaters, removing volume and moderating spate flows. I had a long discussion on this point with Ness Glen, the Spey's fishery scientist, and I'm pleased to note that the Board has finally launched a campaign against hydro abstraction from the Spey. Hydro abstraction is the largest scale and most damaging, but we should not forget the growing demands of domestic supply and agriculture (most notably for watering potato crops).

It is also interesting to observe and note the effect of the changing nature of sewage management. Fifty years ago the populations of many of Scotland's river valleys were in some cases quite similar to today. But they were in fewer households, with much lower water consumption and discharged their sewage to septic tanks and soak-aways. Very little went anywhere near the river. From the 1930s onwards, with the introduction of public amenity water processing, much of this previously enclosed sewage was piped to a single site and the output discharged directly into the rivers. Even if it was processed it was seriously de-oxygenated. Today there are far more households, consuming orders of magnitude more water, and discharging sewage containing every form of chemical, enzyme and pharmaceutical under the sun, much of which passes through treatment unaffected. You can see the changes in time series aerial photos of towns like Aviemore, Grantown, Banchory and Ballater.

As you correctly note, catchments with low densities of human population and without serious agriculture tend to fare much better. The Findhorn is a good example.
 

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Not sure where to start but here goes.
The Findhorn is suffering a decline like most rivers, catches in 2019 were 64% of the 10 yra, and about half of what they were in the mid naughties.
There are many rivers in Scotland that do not have hydro schemes/dams but are still in decline.
The vast majority of the population of Scotland lives near or on the coast where the sewage gets pumped out to sea and not in the rivers.
The water quality of Scottish rivers is better now than it was say 50 years ago when the Salmon runs were better than they are now.
There might be unseen agrichemicals which might be harmful to aquatic life but some agrichemicals will enhance aquatic life such as nitrates and phosphates which encourage algae and plant life that some aquatic insects thrive on.
We fishers tend to complain if we go to a beat that has a lot of weed or a fallen tree that affects our fishing but these things are the reason why the fish are there in the first place
.On land we call it a food chain in water it is known as a food web because they all feed off and live because of each other and if you take one or two elements away such s Salmon kelts or woody debris you break the chain or take a chunk out of the webb.

Here is a couple of links for anyone who disgrees with me
https://www.rmbel.info/the-aquatic-food-web-whos-eating-whom/

say 50 years ago when Salmon numbers were bigger and better
 

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Discussion Starter · #58 ·
Not sure where to start but here goes.
The Findhorn is suffering a decline like most rivers, catches in 2019 were 64% of the 10 yra, and about half of what they were in the mid naughties.
There are many rivers in Scotland that do not have hydro schemes/dams but are still in decline.
The vast majority of the population of Scotland lives near or on the coast where the sewage gets pumped out to sea and not in the rivers.
The water quality of Scottish rivers is better now than it was say 50 years ago when the Salmon runs were better than they are now.
There might be unseen agrichemicals which might be harmful to aquatic life but some agrichemicals will enhance aquatic life such as nitrates and phosphates which encourage algae and plant life that some aquatic insects thrive on.
We fishers tend to complain if we go to a beat that has a lot of weed or a fallen tree that affects our fishing but these things are the reason why the fish are there in the first place
.On land we call it a food chain in water it is known as a food web because they all feed off and live because of each other and if you take one or two elements away such s Salmon kelts or woody debris you break the chain or take a chunk out of the webb.

Here is a couple of links for anyone who disgrees with me
https://www.rmbel.info/the-aquatic-food-web-whos-eating-whom/

say 50 years ago when Salmon numbers were bigger and better
It not really all about rivers though. Our countryside and wildlife in general are getting it tough. There just isn't the same amount of bird life as there was 50 years ago either as there have been massive loses of habitats that supported huge and varied populations of insect life.

A single hay meadow 30 years ago of around 6 acres probably had more species of insects than a 100 acre field now that has been caked in slurry.

It really isn't all about stuff getting washed into rivers. The whole countryside around our rivers has changed and it now seems unable to produce to insect life that it did in previous decades. I feel that this is having a knock on in feeding for juveniles in our rivers.
 
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It not really all about rivers though. Our countryside and wildlife in general are getting it tough. There just isn't the same amount of bird life as there was 50 years ago either as there have been massive loses of habitats that supported huge and varied populations of insect life.

A single hay meadow 30 years ago of around 6 acres probably had more species of insects than a 100 acre field now that has been caked in slurry.

It really isn't all about stuff getting washed into rivers. The whole countryside around our rivers has changed and it now seems unable to produce to insect life that it did in previous decades. I feel that this is having a knock on in feeding for juveniles in our rivers.
I agree 100% we have f**ked up the whole countryside, but i can't help but think we are now too clean, everything that is natural and recyclable whether it be food waste or dead animals is destroyed, and we are starving the country with the recycling it needs to function.
Eels were once abundant in our rivers and were known to eat just about anything and the Elvers were a good source of food for Salmonoids since the rivers are now cleaner? the Eel population has fallen off the earth .
Waste does not have to be pollution if managed in the right way.
A forrest would not survive if it was not for the fallen leaves and dying trees that recycle the nutrients that has made it grow in the first place.

.
 

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I agree 100% we have f**ked up the whole countryside, but i can't help but think we are now too clean, everything that is natural and recyclable whether it be food waste or dead animals is destroyed, and we are starving the country with the recycling it needs to function.
Eels were once abundant in our rivers and were known to eat just about anything and the Elvers were a good source of food for Salmonoids since the rivers are now cleaner? the Eel population has fallen off the earth .
Waste does not have to be pollution if managed in the right way.
A forrest would not survive if it was not for the fallen leaves and dying trees that recycle the nutrients that has made it grow in the first place.

.
A farmer in Devon who came over for a chat on the river Walkham, told me this exact thing and told me that when the local village butchers would let the waste into the water, the river seemed very healthy. His take was that since stopping that, the river was too clean? Certainly eels and even Parr would of eaten and cleaned up dead animal parts and Bones imo
 
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