The Atlantic Salmon
By Jock Monteith 6th April 2021
The Atlantic salmon really is one of the world's most fascinating creatures for many reasons like the ability it has to make the transition from fresh water to sea water when nature sends it to the rich feeding grounds off the coasts of Greenland and the Faroe Isles. At sea these fine fish pack on bodyweight over a one to four year period before the call of nature sends them back to the fresh water rivers to start their reproductive cycle all over again.
The Atlantic Salmon
Salmon are widely known to return to the same stream of their birth although scientific micro tagging study research has located Scottish salmon in Norwegian rivers which means this theory is not 100% accurate. I think the best way to view this is to make a comparison with our human species and understand that genetic evolutionary gene splicing has to also naturally occur to guarantee the genetic intergity of the species and like the human race salmon also have natural exploration instincts.
How A Salmon Navigates
It has always amazed people as to how these fish can navigate thousands of miles to & from their oceanic feeding grounds but from what I've seen over the years here are my views. As a professional salmon guide you get to know intimately where salmon will hold up on any individual stretch of the river. On any salmon fishing venue where over head power lines cross the river you'll always find a salmon lie directly underneath the wires in addition to the beat's other natural salmon lies.
Salmon Fishing Safety
The above is no doubt due to the electro magnetic field caused by live power cables which confuses the salmon's navigational sensors the same way your compass needle would spin if you walked under the same power cables. Great care however must be taken not to be casting close to these man made constructions due to the potential power surge that can arc the electrical current to a fishing rod and cause serious injury or death even when these cables are position high up off the river. The only way to fish these areas is with a long line from an upstream boat or riverbank position and never 'ever' close to the overhead wires or within the often signposted 'no fishing' areas.
Salmon Under Overhead Power Lines
To confirm my theory on the magnetic field that salmon use to navigate I recall power lines being re-sighted by the electricity company on one of the salmon beats I used to work on and amazingly the salmon lie moved instantly to the new power line location and no further salmon were ever seen or caught at the old location which had consistently produced salmon for decades since the wires where originally installed. This was all the hard proof I needed regarding how salmon manage to navigate to sea and back as it became clearly obvious that the magnetic field could be the only viable explanation paired with an acute sense of smell which also assists salmon to return to their natal river.
Salmon River Confluences & Dams
The acute sense of smell that salmon navigate with is also fairly obvious where you've got a tributary river merging with the main river. Sometimes the depth of the main stem of the river will be the reason salmon will congregate in the main river area adjacent to the tributary however to my mind it's likely the mixing of river scents that stops salmon as if confusing them temporarily until they decide which one to go with. In the ideal world a confluence pool with overhead power lines would be the ideal scenario for locating salmon however that could be regarded as less of a challenge the same way catching salmon immediately downstream of a major dam construction would be.