This really is one of the most amazing creatures, a species overlooked and un-noticed by mainstream society. Sometimes referred to as an “indicator” species, despite centuries of study and significant research investment, the factors influencing its population fluctuations remain a subject of intrigue and endless source of study.
Having both read and listened to people with lifetimes experience of this fish, frankly, to both me and most others, it continues to be an enigma. I am sure you will find the following interesting and at the end I will pose a question.
In Scotland, our geographic position means we are perfectly placed to have a long season. By that I don’t just mean a long “fishing” season, I mean a long “reproductive” season!
Salmon enter our rivers all year round, we commonly know them as, Spring, Summer and Autumn salmon runs. However, there is another cohort, most of call them call “Spring” salmon, but in fact, they are “Winter” salmon. Those fish entering our rivers in the months of December, January, and February are very much winter salmon.
Because of their geographical position, the perception is that countries like Norway and Iceland have no Spring salmon, and certainly no winter salmon. The only run of salmon they have are summer fish, i.e. Apart from a very odd one, for the purpose of spawning all the fish enter rivers between May and September. I say the purpose of spawning because this is the only reason they are here in the first place. It is not to provide entertainment or food for all of us anglers. However, when describing or imparting any form of information with regard salmon, anglers have always been the fount of this knowledge. The only reason that “Winter” salmon is not part of the “Salmon” vocabulary, is because we don't fish for them in the winter, so it is simply not relevant. It is for this reason that neither Iceland or Norway has any Spring or Autumn running salmon. However, be assured, there will be early and late running salmon in those countries too. Maybe not as many and prolific as we see in Scotland, but they will be there.
Russia is interesting because they are the only country I know who have a specific name for “Winter” salmon. Here they are called “Osenka” [Ice Fish]. Thos will always have been fished for by locals, hence the name. Those fish arrive in the river in prime condition during late September and keep coming, living under the ice as it forms on the rivers during late October. Those are the fattest and fittest salmon I have ever came across and will not spawn in the river until the following autumn [same as our very early fish]. This is the salmon adapting to local conditions. They are one of the most adaptable creatures on the planet and by sitting back and taking time to look closely we can see this wonderful creature for what it really is. Named Salmo Salar [The leaper] by Linnaeus, I would re name today as Salmo diversus as this describes the king of fish in a far better and more fitting way.
Beyond its migratory patterns, the Atlantic salmon's ability to adapt to diverse environments is extraordinary. Driven by an instinctual urge to reproduce It can colonise in the harshest conditions. Fear and greed, prevalent in human interactions, are absent from the salmon's world. Its sole purpose is to “collectively” find suitable spawning grounds. This, however, is where the teamwork ends. Once on the spawning grounds the fish become territorial and aggressive again, exactly as they were when they were last here.
All those instincts have meant that over millennia he has outfoxed man and every other predator, whether in the ocean or in freshwater, as predators/trouble moves closer, so he moves away and through teamwork and safety in numbers, adapts to that new, unfamiliar environment.
Here's the lead to the question -
One intriguing aspect of the Atlantic salmon's life cycle is the synchronized departure of juvenile fish from rivers. Regardless of their parent's cohort, Winter, Spring, Summer or Autumn, young salmon leave together after a period of territorial behaviour. This uniformity raises questions about the factors that have disproportionately affected certain cohorts, such as the decline of autumn-run salmon? Not so long ago, the Autumn cohort was prolific in many rivers in Scotland. So why have we lost “All” of those and only some of the others?
While the Atlantic salmon faces numerous perceived threats, including - Trawling its food source? Sea lice from Aquaculture? Increase in natural predators? Poor water quality and habitat issues, and a host of others. Which one of those can answer the question above?
I have my own answer to this but would love to hear yours?
In reply to Ronald: Great to see your comments. I was a teenager fishing in the 60's but I'm unsure when your " decade " ended. My contemparaneous memory was of extreme springer losses to disease In Northumberland c > 1967. I believe now ( from Jensen, 1937 ), that there was either no salmon in the Northern Davis Strait then or no fishery capable of identifying a heavy presence. Further, since the years c 1970 saw extreme East-Coast commercial fishery pressure, upon the most valuable cohort, as the same time as the disease UDN targetted this same cohort, when in freshwater, this pressure continued irrespective of these 2 pressures and that was the end of the Goose which laid…
The AST had a SALSEA 11 Merge Conference in Fishmongers Hall, London about 12 years ago. A Scandanavian ( ?Norwegian) scientist asserted there was no need to worry about declining Atlantic Salmon populations as “it has all happened before“ and they will bounce back. His explanation: The NAO (North Atlantic Oscillation) which occurs in approximately 50 year cycles. I think his name is Dr Jens Christensen.
Obviously other factors such as mega trawlers, massive salmon farms and rising ocean temperatures, have crept in which did not exist 50 years ago.
Also I believe a vast amount of wild marine fish are harvested unsustainably, to make fishmeal for salmon farms and feeding livestock, almost certainly at the expense of post-smolts.
These things go in cycles: In the 1960s the main run changed from Spring Salmon to Autumn Grilse (does nobody else remember this?); around 1910, the main run changed from Autumn Salmon to Spring Salmon; there is less information about earlier periods but around 1850 there was a major decline in Grilse and at the end of the 18th century as far as can be told, it switched from Spring Salmon to Grilse. These changes are related to the temperatures in the North-east and North-west Atlantic favouring Grilse or Salmon life-pattern. The big changes in total numbers come from Autumn Grilse: when Grilse numbers are high, they have a larger average weight because there are many late, Autumn Grilse, whe…
Very good article Ian but in my opinion it’s clearly a combination of all of those factors you mention that plays a part. I do like the mackerel theory though as well. I would like to hear your own thoughts but it’s my perception that overall this year we have had a better year catching salmon (when river/weather conditions have been right). What do you think?
Some years ago I attended a conference in Inverness organised by the University of the Highlands and Islands discussing the future of salmon. Many learned scientists were there to speak about their own particular projects. The only one who made any impression on me was a Norwegian?, he was practical, not theoretical and had put in the hours at sea in commercial fishing vessels talking to the skippers as well as time on research vessels.
According to him:
warming of the North Sea resulted in plankton moving further north;
EEC fishing quotas had distorted the fish population and resulted in a massive increase in mackerel;
these mackerel were stunted in growth because there was insufficient food to support the number…