Conference Presentation: Salmon Watch Ireland

KerrySalmon

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Here under a recent presentation at the Salmon Watch Conference on 21 April 2018. The main emphasis of this presentation was to highlight the knowledge gained over the recent decades in regard to mortality factors of juvenile salmon.
  • Marine growth rates varied among years, highest growth rates 2002, followed by 2003 and 2009. Lowest growth rates in 2008 (Very poor returns of 1 SW salmon in 2009 and 2 SW in 2010). 2010 saw a good increase in survival for 1 SW fish.

  • Growth rates during the first period at sea were lowest for salmon of southernmost origin (this would include Ireland). This effectively illustrates that climatic change and altered ocean temperatures are affecting post smolt feeding at entry to ocean and along migration route.

  • Inter-annual variation in wind fields, and thus the surface currents, altered the migration pathways. (Illustrates how important weather patterns in spring are)

  • Likely suspects from headwaters to open ocean to be studied to indicate where mortality occurs
  • Certain areas in ocean where change in migration can be affected to be examined

  • Sharing the resources of the ocean with mackerel, herring and blue whiting as well as pressures from commercial exploitation of these stocks

  • Increased mortality strongly linked to impacts of climate change (++Celcius ), SSC’s and changes in the food supply in the ocean

The presentation is easy to read and any questions you wish to ask can be directed to Salmon Watch Ireland at salmonwatchireland@gmail.com or through this thread.

Conference Presentation Link:
SWIRL Annual Conference April 21st 2018 v3 27.4.18 (1).pdf - Google Drive
 
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salmo76

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No surprises there then, the scientific community is sticking to its guns and putting the main causes of Atlantic salmon declines down to global warming, something we can do nothing about. Now I know I will be placed in the mad heretic camp to be laughed at and ignored but I`m very sceptical of these scientific claims, which to me are often affected by considerations of future research funding and pleasing the political establishment.

As an example, for years the Scientific community have been telling us that polar bears are on their last legs due to global warming, jeez, nearly every time I watch TV I see an advert to send money fast and adopt one to save them. ( lots of money in global warming you understand). Yet a few weeks ago in a small snippet, well buried in the news, was an official report that polar bear numbers are not down at all and are in fact increasing.

Over here in SW Scotland I can see no signs of a rapidly warming climate, we have had lots of long cold winters in recent years and very cold springs ,followed by cool wet summers. I checked the sea temperatures in the Firth of Clyde this March and the graph was showing a record low. Also, it doesn`t make sense to me that we had a record season in 2010 with global warming still very much at its worst in the NW Atlantic, according to the Scientific community. The question also arises, why have some pristine rivers in the far North had large runs of fish in recent years if they are all dying at sea due to global warming ?
 

mows

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Looks like a lot of snouts at the trough.

Of course its all at sea.

There's less mackerel, less herring, less blue whiting, less cod, less Bluefin Tuna.

Sorry, got that wrong, they are all on the increase.

Its a shame, all the food is labeled only for them, because if not, the smolts could be eating lots as well.

Im never comfortable with a begging letter that claims by 2030, salmon will probably be threatened with extinction if nothing is done.

Again, why do they always quote "UP TO 25% RETURN RATE"
Did this include hypothetical netting?
What was the average rate?

What is the highest return rate anywhere now and why isn't it also quoted.

Re climate change, I do think there may be a point here re smolts trending towards S1 instead of S2 and S3.

However, it could also be because the huge increase of in river predation, means that few smolts live to s2 or s3.

I would be interested in the average size of smolts over the last 20 years, as all the ones im seeing on river board sites look tiny to me.

Size should be a big factor in marine survival rates.

Cheers

Mows
 

KerrySalmon

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No surprises there then, the scientific community is sticking to its guns and putting the main causes of Atlantic salmon declines down to global warming, something we can do nothing about. Now I know I will be placed in the mad heretic camp to be laughed at and ignored but I`m very sceptical of these scientific claims, which to me are often affected by considerations of future research funding and pleasing the political establishment.

As an example, for years the Scientific community have been telling us that polar bears are on their last legs due to global warming, jeez, nearly every time I watch TV I see an advert to send money fast and adopt one to save them. ( lots of money in global warming you understand). Yet a few weeks ago in a small snippet, well buried in the news, was an official report that polar bear numbers are not down at all and are in fact increasing.

Over here in SW Scotland I can see no signs of a rapidly warming climate, we have had lots of long cold winters in recent years and very cold springs ,followed by cool wet summers. I checked the sea temperatures in the Firth of Clyde this March and the graph was showing a record low. Also, it doesn`t make sense to me that we had a record season in 2010 with global warming still very much at its worst in the NW Atlantic, according to the Scientific community. The question also arises, why have some pristine rivers in the far North had large runs of fish in recent years if they are all dying at sea due to global warming ?
OK but you have not looked at the presentation in depth. Yes climatic change is a major cause but not the only one. Record years can be explained by many factors. 2009 was a very good growth year for post smolts and in Ireland we had some increase in numbers but nothing like even 20 years ago. If smolts from Ireland are experiencing poor growth on beginning of migratory path then they will have poor survival. We have pristine rivers in Ireland in some areas which are not performing and are in rapid decline. The temperatures which need to be looked at are on the continental shelf and not localised bays. As sea temps go up it has been shown to affect survival. Northern Scotland is not Ireland and their migratory path is not even similar. All salmon do not go to the same areas of the Norwegian sea but have a wide geographical spread within that area. We have a number of rivers in my locality which have collapsed despite pristine conditions while other rivers are holding their own (AT A LOW LEVEL). The interesting aspect of the presentation also alluded to weather patterns affecting survival on migration as wind can change currents and basically salmon post smolts can be carried to areas which may not be as productive. Climatic change is happening in Ireland with now frequent violent storms and even a hurricane with record winter rainfall and indeed summer rainfall over the last number of years. No one is ruling out other factors and it was interesting to look at freshwater events which can result in collapse of stocks through flooding or drought. Using hatchery smolts as a proxy although not as good as wild fish, their survival has plummeted despite being reared in same conditions as they were when their survival was excellent. No one rules out bye catch (An entire cohort of smolts could be taken from a specific river if unlucky to be there when nets are being fished in an area) or predators or that the Nordic seas are now home to vast quantities of mackerel, herring and blue whiting which could be competing with salmon post smolts. Science certainly demonstrates that fish have poorer growth in certain years and this co-relates with survival. The final number of slides examines the headwaters to the ocean and this project must be advanced to see if we can see where bottlenecks are happening. One more point that was clear is that last year saw an increase to over 7% the survival of 1 SW fish in Ireland which was evident in the early summer. Another very exciting development is the use of eDNA probe which was designed here in Ireland and will be used to search and investigate pelagic boats to ascertain if salmon smolts / pre adults have been in catch. This probe will also be able to determine total weight of salmon in catch.
 

KerrySalmon

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Looks like a lot of snouts at the trough.

Of course its all at sea.

There's less mackerel, less herring, less blue whiting, less cod, less Bluefin Tuna.

Sorry, got that wrong, they are all on the increase.

Its a shame, all the food is labeled only for them, because if not, the smolts could be eating lots as well.

Im never comfortable with a begging letter that claims by 2030, salmon will probably be threatened with extinction if nothing is done.

Again, why do they always quote "UP TO 25% RETURN RATE"
Did this include hypothetical netting?
What was the average rate?

What is the highest return rate anywhere now and why isn't it also quoted.

Re climate change, I do think there may be a point here re smolts trending towards S1 instead of S2 and S3.

However, it could also be because the huge increase of in river predation, means that few smolts live to s2 or s3.

I would be interested in the average size of smolts over the last 20 years, as all the ones im seeing on river board sites look tiny to me.

Size should be a big factor in marine survival rates.

Cheers

Mows
Yes there are more mackerel, herring and blue whiting in NORDIC Seas than ever before and these fish have increased their distribution more Northwards and Westwards. Make no mistake these are fish that can delete a resource over a wide geographic area. Warming water seems to be the driver of this migration and traditional smolt feeding areas are now home to these fish as well as the large pelagic fleets which follow them. They just didn't decide to go on a trip north, they are migrating and surviving due to optimum conditions in these regions which may not have been there decades ago. The virtual disappearance of herring from the Nordic seas in the 1970's co-incided with huge numbers of salmon in UK and Ireland, think about it. These pelagic fish (Mackerel and Herring feed by using their gill rakers to filter zooplankton and can deplete resources over large areas). These are competitors of post smolts and may indeed predate smolts on their migration. ZooPlankton is radically changed in these areas as well with more temperate species moving northwards thus in all probability with pelagic fish in tow. We certainly in my area have no real increase in predation within rivers with cormorant numbers low and seal population static according to field studies carried out over the last decade.Control the controllables is the new buzz word but you need real evidence to get legal permissions to kill protected species. We got rid on drift netting and it made little difference but having spoken to the fishermen at length it was evident that numbers had radically declined and size and condition of fish was very poor.
 

seeking

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Looks like a lot of snouts at the trough.

Of course its all at sea.

There's less mackerel, less herring, less blue whiting, less cod, less Bluefin Tuna.

Sorry, got that wrong, they are all on the increase.

Its a shame, all the food is labeled only for them, because if not, the smolts could be eating lots as well.

Im never comfortable with a begging letter that claims by 2030, salmon will probably be threatened with extinction if nothing is done.

Again, why do they always quote "UP TO 25% RETURN RATE"
Did this include hypothetical netting?
What was the average rate?

What is the highest return rate anywhere now and why isn't it also quoted.

Re climate change, I do think there may be a point here re smolts trending towards S1 instead of S2 and S3.

However, it could also be because the huge increase of in river predation, means that few smolts live to s2 or s3.

I would be interested in the average size of smolts over the last 20 years, as all the ones im seeing on river board sites look tiny to me.

Size should be a big factor in marine survival rates.

Cheers

Mows
With all the increased synchems etc. in many of our rivers nowadays, no wonder the wee blighters want to get out to the safety of the sea ASAP... :eek:

Not many research $$s for that kind of thing though. Climate Change is where it's at.

The thing we're missing here, and perhaps it could be relevant to Salmon Watch Ireland and the OP'er, is that because nets were banned, surely things would have got better by now :confused: That appeared to be one of the main dogmas behind "save our salmon". And yet, some of the best performing rivers or areas appear to still have significant netting operations (and no aquaculture).

And yet, and yet... Go figure.

Climate changes, salmon survive, cyclic abundance varies, rivers recover so long as they are able, salmon are the ultimate survivor. Salmon anglers mind, get bored and put their rods away.

Snouts at the trough, Mows, shoorely shome mishtake...
 

mows

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Yes there are more mackerel, herring and blue whiting in NORDIC Seas than ever before and these fish have increased their distribution more Northwards and Westwards. Make no mistake these are fish that can delete a resource over a wide geographic area. Warming water seems to be the driver of this migration and traditional smolt feeding areas are now home to these fish as well as the large pelagic fleets which follow them. They just didn't decide to go on a trip north, they are migrating and surviving due to optimum conditions in these regions which may not have been there decades ago. The virtual disappearance of herring from the Nordic seas in the 1970's co-incided with huge numbers of salmon in UK and Ireland, think about it. These pelagic fish (Mackerel and Herring feed by using their gill rakers to filter zooplankton and can deplete resources over large areas). These are competitors of post smolts and may indeed predate smolts on their migration. ZooPlankton is radically changed in these areas as well with more temperate species moving northwards thus in all probability with pelagic fish in tow. We certainly in my area have no real increase in predation within rivers with cormorant numbers low and seal population static according to field studies carried out over the last decade.Control the controllables is the new buzz word but you need real evidence to get legal permissions to kill protected species. We got rid on drift netting and it made little difference but having spoken to the fishermen at length it was evident that numbers had radically declined and size and condition of fish was very poor.
Hi Kerrysalmon,

Maybe I picked this up wrong, but are you saying

That there is now that much abundance of food in these seas that the feeding of Mackerel and herring is so good, that there shoals become as large as to create a shortage of food and the smolts starve, but not the other fish?

Cheers

Mows
 

KerrySalmon

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With all the increased synchems etc. in many of our rivers nowadays, no wonder the wee blighters want to get out to the safety of the sea ASAP... :eek:

Not many research $$s for that kind of thing though. Climate Change is where it's at.

The thing we're missing here, and perhaps it could be relevant to Salmon Watch Ireland and the OP'er, is that because nets were banned, surely things would have got better by now :confused: That appeared to be one of the main dogmas behind "save our salmon". And yet, some of the best performing rivers or areas appear to still have significant netting operations (and no aquaculture).

And yet, and yet... Go figure.

Climate changes, salmon survive, cyclic abundance varies, rivers recover so long as they are able, salmon are the ultimate survivor. Salmon anglers mind, get bored and put their rods away.

Snouts at the trough, Mows, shoorely shome mishtake...
Sorry but we agree that all problems are not at sea but look at the evidence in an objective manner. We knew that the stocks would not recover after the drift net ban but that it would buy time to address other similar controllables. If you assert that salmon will come back, yes they may but we live in an era where we want them back now. Rivers without salmon will be destroyed as there will be no real interest in them and angling is now not a very popular pursuit. Research in rivers is ongoing in Ireland in relation to water quality and ecological functionality but again our agricultural economy takes precedence. Certainly smolt numbers have declined with water quality and habitat destruction but we did not envisage that certain rivers( the majority would see a decline in the period from 2008 in adult returns). My nearest river here had 2750 salmon through the counter in 2007 but now has at best just shy of 500 fish, this decline was evident in 2008 when the count dropped by 80% and has hovered around 300-500 fish per year. There has been no discernable change to habitat or water quality so this rivers problems are certainly at sea. It is noteworthy that this was a late river with grilse and salmon arriving in numbers from July to August and this pattern of decline is evident around Ireland which share this run timing. The earlier grilse and salmon rivers are holding their own (Low level) but not really improving.
 

KerrySalmon

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Hi Kerrysalmon,

Maybe I picked this up wrong, but are you saying

That there is now that much abundance of food in these seas that the feeding of Mackerel and herring is so good, that there shoals become as large as to create a shortage of food and the smolts starve, but not the other fish?

Cheers

Mows
Yes if you understand ecology it is evident that if an invasion of a species into an area which it has not been in abundance before then you may have a problem as these fish may reduce available resources which can have a cascade of effects. Reduced zooplankton reduces larval fish and other food items in the food chain which may in turn reduce availability of food for salmon. Also now the zooplankton is not similar to times of salmon abundance in the past with more temperate species in vogue not the sub artic species which were more helpful to salmon growth. It would be difficult to say that not enough food is available but maybe there is not the supply of the right types to have an ecosystem which is optimum for salmon. However increased fishing pressure must be problematic with bye catch. Certainly growth rings tell the story as in years where feeding is poor you will experience less survival. Feeding in the first year has been observed to influence survival. If the fish grows normally it probably negates the threat of predation. Our salmon in Ireland experienced the poorest growth rate which indicates that the more southern you are the less availability of food there is, or maybe our waters have warmed to the extent that energy has to be expended to get food which effectively reduces growth. Another problem which may happen is predation of mackerel on post smolts. It was believed that if salmon reached a certain size they would predate on mackerel but they must reach this size.Therein may lie the problem.
 

mows

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Yes if you understand ecology it is evident that if an invasion of a species into an area which it has not been in abundance before then you may have a problem as these fish may reduce available resources which can have a cascade of effects. Reduced zooplankton reduces larval fish and other food items in the food chain which may in turn reduce availability of food for salmon. Also now the zooplankton is not similar to times of salmon abundance in the past with more temperate species in vogue not the sub artic species which were more helpful to salmon growth. It would be difficult to say that not enough food is available but maybe there is not the supply of the right types to have an ecosystem which is optimum for salmon. However increased fishing pressure must be problematic with bye catch. Certainly growth rings tell the story as in years where feeding is poor you will experience less survival. Feeding in the first year has been observed to influence survival. If the fish grows normally it probably negates the threat of predation. Our salmon in Ireland experienced the poorest growth rate which indicates that the more southern you are the less availability of food there is, or maybe our waters have warmed to the extent that energy has to be expended to get food which effectively reduces growth. Another problem which may happen is predation of mackerel on post smolts. It was believed that if salmon reached a certain size they would predate on mackerel but they must reach this size.Therein may lie the problem.
Hi Kerrysalmon,

Im not sure this is the introduction of an invasive species, as much as increase in populations due to a huge increase in food. (for everything but smolts??)
I would also have thought that the huge shoals of whitebait and young mackerel would also provide additional sources of food.
I understand from your perspective, but from my rivers, unless you can demonstrate that the Don and South Esk smolts go somewhere different to the North Esk and Dee smolts, then I will stick with my personal hypothesis that the majority of issues are in river, be that food availability, fish predation, pollution (agricultural and domestic), or quality and suitability of smolt and smolt size.

Cheers

Mows
 

KerrySalmon

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Hi Kerrysalmon,

Im not sure this is the introduction of an invasive species, as much as increase in populations due to a huge increase in food. (for everything but smolts??)
I would also have thought that the huge shoals of whitebait and young mackerel would also provide additional sources of food.
I understand from your perspective, but from my rivers, unless you can demonstrate that the Don and South Esk smolts go somewhere different to the North Esk and Dee smolts, then I will stick with my personal hypothesis that the majority of issues are in river, be that food availability, fish predation, pollution (agricultural and domestic), or quality and suitability of smolt and smolt size.

Cheers

Mows
Here is an interesting article from a Norwegian Scientist in relation to mackerel. I would agree with the majority of this but the temperature change may take some time to affect salmon survival and the film did certainly mention mackerel as far as I can remember. Interesting.
Norwegian salmon scientist Jens Christian Holst
As a marine fisheries biologist I have worked closely on the marine ecology and factors affecting marine survival of Atlantic salmon since 1991. I have seen ‘Atlantic Salmon Lost at Sea’ and it came to me as a scientific disappointment when temperature and climate change was the explanation for why the salmon are not coming back as they used to do.
Based on my ecosystembased research in the NE Atlantic I have developed the ‘Hypothesis on overgrazing and predation’ which I strongly advise you to consider in parallel with ‘The temperature and climate change hypothesis’ while watching the film.
Today the NE Atlantic mackerel stock has grown totally out of proportions due to strong underestimation leading to too low quotas allocated, which again leads to underfishing. Because of the very large mackerel stock the food resources of amongst other whales, seals, sea birds, salmon and the mackerel itself are now heavily overgrazed. Today a 7 years old mackerel weighs half of what it would have weighed 10 years ago, a clear sign of the overgrazing. The lack of food also lead to starvation and very slow growth of the young salmon at sea, the salmon postsmolt. This make the postsmolt salmon more vulnerable to predation and disease than before the mackerel explosion.
A 30 cm long mackerel can eat a 12.5 cm mackerel (Figure 1) meaning a mackerel can eat a fish 40% its own length. This again means a mackerel at 50 cm can eat a 20 cm postsmolt salmon. In other words, mackerel can prey efficiently on postsmolt salmon during much of the postsmolts first summer at sea.
Traditionally the main spawning grounds of the NE Atlantic mackerel stock were found west of the British Isles and in the North Sea. Due to the strong stock growth, the mackerel spawning areas have swelled northwards and it now also spawn in the Norwegian Sea and in Norwegian fjords, way up to Northern Norway. In May 2008 we found spawning mackerel with the marine research vessels in the Norwegian Sea for the first time, a trend which has strongly intensified in later years.
The mackerel and the salmon postsmolts both use the shelf edge currents west of the European continent to speed up their northern feeding migration in late spring, thus inhabiting exactly the same waters, and also depths. This close ‘coswimming’ of mackerel and salmon postsmolts during the entire 2000 kilometre migration from Irish river mouths to north of the Vøring plateau in the Norwegian Sea at 68 degrees north makes up the perfect predation opportunity for the starving mackerel on the now more slow growing and vulnerable Irish postsmolts (Figure 2). Knowing this migration takes about two months I leave it to yourself to consider what the effect of predation from mackerel could be on the Irish salmon postsmolt during this migration today.
The Irish and Northern-Irish salmon has collapsed at a much higher and more alarming rate than the Norwegian salmon stocks, despite about 1.3 million tonnes of salmon being farmed in Norway. But the Irish and Northern-Irish postsmolts both have to ‘coswim’ with the dense concentrations of mackerel northwards more than double the distance and period compared with the Norwegian postsmolts.
The measured mackerel egg distributions in 1992 (Figure 3) and 2016 (Figure 4) demonstrates the increase of the mackerel spawning stock and the dramatic increase in predation potential of mackerel on the postsmolts of Irish salmon, in perfect parallel with the collapse of the Irish salmon stocks. Figure 5 further shows how the growing mackerel stock expanded its spawning area into the Norwegian Sea from 2008 onwards.
At the end of ‘Atlantic Salmon: Lost at Sea!’ it is concluded “What we know now is that climate change has impacted directly and very severely on Atlantic Salmon at sea”. In my view there is no empiric basis for such a conclusion. If we study the development of the temperatures in the main feeding area of Irish postsmolts in the Norwegian Sea, the temperatures rose from around 1970 to 2007 and are now close to or below normal according to the Institute of Marine Research (IMR) in Norway. In the IMR 2017 ‘Marine Research report’ (Havforskningsrapporten) it is stated on page 16: “The Norwegian Sea: The temperatures in the Atlantic water along the Norwegian continental shelf have since 2013 been close to or slightly above normal. The temperatures in 2016 were mainly above normal, except the southeastern Norwegian Sea were the temperatures were lower than normal.”

The temperatures in the Norwegian Sea follows the so-called Atlantic Multidecadal Oscillation (AMO). This 60 years climate cycle bottomed in the early 1970ies, peaked around 2007 and must now be expected to be negative for about 20 more years from now. Climate change may lead to higher temperature at the coming peaks and bottoms but I expect the cycling to continue like is documented in for instance sedimentation layers on the seabed all since the last ice age 10.000 years ago. Read more about AMO for instance on Wikipedia

So, during a period of continuous decline of Irish salmon from around 1973, the temperatures in its main feeding areas have been going up, peaking in 2007 and then down to around normal today. There is consequently no correlation with temperatures in the Irish salmon stock collapse but a very good correlation with the growing mackerel stock and its potential for predation on the Irish postsmolt salmon.

Despite the AMO having turned negative more than 10 years ago the Irish and Northern-Irish salmon stocks continue their negative spiral and fishing have almost ceased as the salmon stocks are close to or under conservation limits. In my view this situation will continue to worsen for the Irish salmon until we reduce the heavy competition and predation from mackerel.
Today the Norwegian Sea and Norwegian coast is ‘filled up’ with juvenile mackerel after two years of very successful recruitment from the never seen before northern spawning in 2016 and 2017. Consequently, the worst may well be yet to come for the Irish and European salmon in my view.
 

Grassy_Knollington

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Interesting stuff, nice to see MR Holst doing some critical analysis of the prevailing view WRT temperature.

What stands out to me is what we regard as a problem, both in general and for Salmon stocks in particular. Specifically, should we really be classifying apparently natural events as problems and seeking (no pun intended) to 'solve' them, when we should be accepting the variation as part of a / the cycle.

Over the last 100+ years the prevailing conditions have favored either early-running MSW fish or later running 1SW fish. We can attribute this to Mackerel or Whiting, or temperature, or phytoplankton abundance or ocean currents, or a combination of these things. It doesn't really matter that much IMO, the key lessons are that this behavior has happened before and that it is driven by macro-changes in the environment, over which we have little or no apparent control.

Of course Mr Holst could be completely correct and the Salmon may be reliant on human exploitation of Mackerel to reach optimal abundance. We are part of the system and in that context, his arguments make some sense. I'm a little skeptical about that though. If, as he asserts, the temperatures are close to the historic norms and as he infers, human exploitation of mackerel is the limiting factor on Mackerel abundance; then surely pre industrialization Mackerel would have been even more abundant and 1SW survival even lower than it is now?

Another subject raised by his theory is the possible need to increase Plagic fishing to cope with the excess Mackerel. If the 'Lost at Sea' theories are correct, then increased Mackerel fishing would also catch an increased number of Post-Smolts, would this not negate any benefit gained by the additional fishing effort? \

I think the whole system is so complex that we are unlikely to be able to resolve specific, addressable causes and then actually do something about them. I think all we can do is to get as many Smolts out to sea as possible , make the coastal environment as friendly as we can and wait for the results.
 

KerrySalmon

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Interesting stuff, nice to see MR Holst doing some critical analysis of the prevailing view WRT temperature.

What stands out to me is what we regard as a problem, both in general and for Salmon stocks in particular. Specifically, should we really be classifying apparently natural events as problems and seeking (no pun intended) to 'solve' them, when we should be accepting the variation as part of a / the cycle.

Over the last 100+ years the prevailing conditions have favored either early-running MSW fish or later running 1SW fish. We can attribute this to Mackerel or Whiting, or temperature, or phytoplankton abundance or ocean currents, or a combination of these things. It doesn't really matter that much IMO, the key lessons are that this behavior has happened before and that it is driven by macro-changes in the environment, over which we have little or no apparent control.

Of course Mr Holst could be completely correct and the Salmon may be reliant on human exploitation of Mackerel to reach optimal abundance. We are part of the system and in that context, his arguments make some sense. I'm a little skeptical about that though. If, as he asserts, the temperatures are close to the historic norms and as he infers, human exploitation of mackerel is the limiting factor on Mackerel abundance; then surely pre industrialization Mackerel would have been even more abundant and 1SW survival even lower than it is now?

Another subject raised by his theory is the possible need to increase Plagic fishing to cope with the excess Mackerel. If the 'Lost at Sea' theories are correct, then increased Mackerel fishing would also catch an increased number of Post-Smolts, would this not negate any benefit gained by the additional fishing effort? \

I think the whole system is so complex that we are unlikely to be able to resolve specific, addressable causes and then actually do something about them. I think all we can do is to get as many Smolts out to sea as possible , make the coastal environment as friendly as we can and wait for the results.
Absolutely agree but we need to know if we are the problem in that why are mackerel so abundant in these areas now and did this occur before, pre industrialized times were mackerel up there, I cannot find research to say they were as far north. Are we causing this by our emissions indirectly and can we change, not really probable at this stage. Certainly getting as many smolts to sea will help but if migration route has either lack of food or increased predation we may fail. Have a look at East Machias in states, they have done a Tyne project but sadly no real return as of yet so they seem to have ocean problems dominating their returns. The weather patterns appear to be very important in their effect and this might give us some clue as to why we have problems. I know that Pacific salmon interests are actively working with scientists here to look at ocean problems but they also suggest that freshwater events can have alarming impacts on salmon survival at population level. Warm low rivers above lethal levels, massive winter floods and indeed summer floods can have a devastating effect. I remember vaguely reading that floods in August can have a significant effect on young of year salmon. I know here in Ireland a well respected researcher linked length of grass growing season (Spring) to sea trout juvenile survival over a long time period, think of it as temperature, light and warming water boosting growth levels to reach smoltification. He concluded that if these fish did not reach a certain stage to smoltify they would remain for another year and cause density problems thus reducing the stock. Are our salmon smolts fit enough for sea entry and are they running earlier which can be a mismatch with conditions at sea.
 

Loxie

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Looks like a lot of snouts at the trough.

Of course its all at sea.

There's less mackerel, less herring, less blue whiting, less cod, less Bluefin Tuna.

Sorry, got that wrong, they are all on the increase.

Its a shame, all the food is labeled only for them, because if not, the smolts could be eating lots as well.

Im never comfortable with a begging letter that claims by 2030, salmon will probably be threatened with extinction if nothing is done.

Again, why do they always quote "UP TO 25% RETURN RATE"
Did this include hypothetical netting?
What was the average rate?

What is the highest return rate anywhere now and why isn't it also quoted.

Re climate change, I do think there may be a point here re smolts trending towards S1 instead of S2 and S3.

However, it could also be because the huge increase of in river predation, means that few smolts live to s2 or s3.

I would be interested in the average size of smolts over the last 20 years, as all the ones im seeing on river board sites look tiny to me.

Size should be a big factor in marine survival rates.

Cheers

Mows

People have been quoting 25% survival 20 years ago for over a hundred years, starting with Calderwood. It's never, ever been measured at that. 3 to 8% averages with 2 to 12% minimum and maximum and the odd outlier seem to be the case for Smolt to adult survival to rivers wherever and whenever it's been accurately measured, rather than guessed. MCXFisher's quoted University of Maine meta analysis showed this consistently from the 1950's.

The most recent years have been very good; 2015 and 2016 are amoungst the very best smolt to adult ratios recorded on the Frome since they began recording in 1995 at well over 8%. (It should be noted that this is measured some distance upstream from the tide in a river with big pike, plenty of pisciverous birds and an estuary famous for bass, so will be much lower than the actual "marine survival" rate).
 

nore fly

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Interesting reading...but just one point that is been missed our over looked...the runs of salmon for the first two years after the drift net ban were massive and it did benefit runs...the rivers were packed with fish...then bang gone....so what happened. .???
Did a fishery somewhere off some coast ..that was not worth fishing for salmon suddenly see the benefits of those two years and reopened and has all the benefits where as when the drift nets operated it was a more shared plundering...just a taught and two much day dreaming...
 

Loxie

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Interesting reading...but just one point that is been missed our over looked...the runs of salmon for the first two years after the drift net ban were massive and it did benefit runs...the rivers were packed with fish...then bang gone....so what happened. .???
Did a fishery somewhere off some coast ..that was not worth fishing for salmon suddenly see the benefits of those two years and reopened and has all the benefits where as when the drift nets operated it was a more shared plundering...just a taught and two much day dreaming...
The trouble with salmon is that the natural fluctuations are so extreme that a year or two can be terrible then a year or two can be fabulous. 5 or ten year averages give a rather better view.
 

KerrySalmon

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The trouble with salmon is that the natural fluctuations are so extreme that a year or two can be terrible then a year or two can be fabulous. 5 or ten year averages give a rather better view.
10 and 5 year averages here are extremely poor. Salmon runs fell off a cliff in 2009 in Ireland and have remained poor since with maybe some increase noted last year. Late running grilse are missing from all our rivers. Hardly any fresh fish entering systems after mid July. Spring runs appeared better this year but have flattered to deceive with poor returns since mid April.
 

KerrySalmon

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Interesting reading...but just one point that is been missed our over looked...the runs of salmon for the first two years after the drift net ban were massive and it did benefit runs...the rivers were packed with fish...then bang gone....so what happened. .???
Did a fishery somewhere off some coast ..that was not worth fishing for salmon suddenly see the benefits of those two years and reopened and has all the benefits where as when the drift nets operated it was a more shared plundering...just a taught and two much day dreaming...
I doubt it and the problem is countrywide and Scotland seems to have problems with late running grilse and summer/autumn salmon. I fished the Nore in 2007/8 and it was fantastic but has now drifted very poorly. The big problem now is the lack of spawners on this great river. Saying that if we have good survival years you might see benefits.
 

Canewizard

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What about the myriads of resistent lice drifting in the same currents than the smolts? Climate change doesn't help either. If I remember correctly, with a two degree warming, the lice's life-/reproduction cycle shortens from about 50 days to 17!. If louse concentration exceeds 0,1 per gramm of fish, it triggers a possibly lethal autoimmune reaction. It's a norwegian study as well and seems more likely, at least to me, than the Mackerel predation theory. Not saying it doesn't contribute to the problem as a whole, together with a high number of other anthropogenic impacts...
Usually in situations like this, species adapt. But only if there's no (human) interference. Now, that's not gonna happen, is it?
I wish humans wouldn't be so damn ignorant and selfcentered.
Salmon are not a resource anymore, or at least mustn't be treated as one. I know anglers can hardly ruin a healthy river, but how many healthy rivers are left? I've more or less been growing up with C&R in place or around the corner and I can live with it, although I didn't contribute much to the situation(Don't even have a car)
So why can't YOU (those who won't stop arguing over C&R) do the same and let salmon adapt?
Unfortunately the general public doesn't seem to care or is too limited to understand, whether stocks are depleted, habitats destroyed, species extinct, unless it threatens their microcosm or comfort zone. But I'd like to see a different reaction from anglers, to show they actually care and are willing to stand back. Now, am I being naive? I believe so...
What a sad, doomed place this has become...
 

Loxie

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10 and 5 year averages here are extremely poor. Salmon runs fell off a cliff in 2009 in Ireland and have remained poor since with maybe some increase noted last year. Late running grilse are missing from all our rivers. Hardly any fresh fish entering systems after mid July. Spring runs appeared better this year but have flattered to deceive with poor returns since mid April.
Interesting. The Exe, although historically a spring river, has relied on large grilse runs since the late 1980's. 2009 saw the start of a short period of increasing runs again peaking in 2012. Since 2013, however, it's fallen off a cliff with an absence of grilse and precious few salmon as well. The Scottish North Coast rivers have done really well since 2009, with the exception of the 2013 drought and the 2014 generally poor year everywhere, with increasing runs every year.

I think the effect of global warming are bound to be affecting the warmer, southerly and westerly, parts of these Islands more than the colder more Northerly bits? There is no doubt the the warm winter of 2015/6 effectively wiped out spawning for that year in most places. I think the 2013 smolt run was the earliest I've ever seen with smolts running here, the lower river Barle on Exmoor, in February. I think that accounted for the shocking grilse runs of 2014. I suspect it effects inshore sea waters as well and it might be this cumulative effect that accounts for differences.
 

Loxie

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What about the myriads of resistent lice drifting in the same currents than the smolts? Climate change doesn't help either. If I remember correctly, with a two degree warming, the lice's life-/reproduction cycle shortens from about 50 days to 17!. If louse concentration exceeds 0,1 per gramm of fish, it triggers a possibly lethal autoimmune reaction. It's a norwegian study as well and seems more likely, at least to me, than the Mackerel predation theory. Not saying it doesn't contribute to the problem as a whole, together with a high number of other anthropogenic impacts...
Usually in situations like this, species adapt. But only if there's no (human) interference. Now, that's not gonna happen, is it?
I wish humans wouldn't be so damn ignorant and selfcentered.
Salmon are not a resource anymore, or at least mustn't be treated as one. I know anglers can hardly ruin a healthy river, but how many healthy rivers are left? I've more or less been growing up with C&R in place or around the corner and I can live with it, although I didn't contribute much to the situation(Don't even have a car)
So why can't YOU (those who won't stop arguing over C&R) do the same and let salmon adapt?
Unfortunately the general public doesn't seem to care or is too limited to understand, whether stocks are depleted, habitats destroyed, species extinct, unless it threatens their microcosm or comfort zone. But I'd like to see a different reaction from anglers, to show they actually care and are willing to stand back. Now, am I being naive? I believe so...
What a sad, doomed place this has become...
I think you are being naive if you think going from 85% CR to 95% CR will have any effect at all.
 

KerrySalmon

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I think you are being naive if you think going from 85% CR to 95% CR will have any effect at all.
Generally lice are a regional problem and as such do not probably affect smolts in open ocean due to wind and current configuration resulting in lice being predominantly in near coastal areas. The issues relating to catch and release are complex but has little effect when stocks are above their conservation limit. For stocks below this limit, Catch and Release does help to boost egg deposition and ensure more juveniles in catchments.Salmon are a fish which interests us primarily for our enjoyment and sport but if we were taking about fish that did not interest us we would not have any interest if they were in trouble, you don't see many research projects into sticklebacks etc. As always we believe that we can change natural processes and give an advantage to certain species to meet our own view of the world. Lets kill all the cormorants and seals is a very common call but are we deluding ourselves. We in Ireland got rid of the largest predator of adult salmon (Drift Net 100 K fish every year and up to 1 million in 1970's) but it made little difference.
 

seeking

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I think you are being naive if you think going from 85% CR to 95% CR will have any effect at all.
The available evidence would seem to suggest that going from 0% C&R (i.e. C&K), coupled with abundant netting, to 100% C&R (CCR) and banning nets won't have any effect either.

(Other than forcing concerned anglers off the banks, and replacing them with those who prefer sloganeering, perhaps, and after that, where is there to go :confused: )


Far better to look into human development and synchems, IMHO.
 

Canewizard

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I think you are being naive if you think going from 85% CR to 95% CR will have any effect at all.
I didn't mean to make this impression. It's not an ideal world, so there's no ideal solution, else everybody would play their part, including industries and governments.
I also didn't mean to address rivers with a high C&R quota, but the ones were 80% or more are battered on the head. I'm sure, this makes a difference.
Don't get me wrong, fishing should be the last field for restrictions and regulations, but I feel somewhat responsible too and I think everybody should.

Cheers 😉

Here's a video link to the study I referred to

https://m.youtube.com/watch?v=SqA4PL40ATE
 

Loxie

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Generally lice are a regional problem and as such do not probably affect smolts in open ocean due to wind and current configuration resulting in lice being predominantly in near coastal areas. The issues relating to catch and release are complex but has little effect when stocks are above their conservation limit. For stocks below this limit, Catch and Release does help to boost egg deposition and ensure more juveniles in catchments.Salmon are a fish which interests us primarily for our enjoyment and sport but if we were taking about fish that did not interest us we would not have any interest if they were in trouble, you don't see many research projects into sticklebacks etc. As always we believe that we can change natural processes and give an advantage to certain species to meet our own view of the world. Lets kill all the cormorants and seals is a very common call but are we deluding ourselves. We in Ireland got rid of the largest predator of adult salmon (Drift Net 100 K fish every year and up to 1 million in 1970's) but it made little difference.
The problem isn't, IMO, solvable by reducing adult exploitation. The drift nets were taking fish spread about every river from Mediterranean to the Mersey, so 100,000 is not really likely to show up in any one region.

I think where agricultural diffuse pollution causing siltation is the main problem: i.e. the Frome, you could kill most of the returning adults and make no difference because most redds are in areas where none of the eggs will hatch, there is only a tiny amount of useable spawning habitat. Increase the habitat and numbers will increase. I'm sure this is common to a vast swathe of rivers from Devon to Aberdeen. Populations that have been reduced due to lost habitat still produce a big surplus of adults relative to that habitat. If a river that had a run of 3,000 fish now gets a run of 800, you might think every adult is too precious to risk. If there is only spawning habitat for 200 pairs whereas there was habitat for 750 pairs the same percentage of adults can be taken without harming the river. This is why reducing exploitation doesn't, and indeed cannot, work.

We know from the Girnock burn that a very small number of adults can produce the maximum number of smolts and therefore it seems likely that, with the exception of recovering rivers and those with large amounts of new habitat becoming available, all rivers produce a very large surplus of adults however small the run is compared to historical records.
 
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