Skip to comments.Re-hashing a 25 year old theory on how Salmon might find their way back to their Scottish birthplace
Posted on 01/19/2013 7:56:55 PM PST by SunkenCiv
Every year, 20 million of them leave Scottish rivers and travel thousands of miles to Norway and Greenland to feed. Remarkably, they then return to Scotland, often to within 100 metres of where they were hatched, in a process that can take more than two years.
How salmon complete such voyages across sea and ocean without getting lost has baffled scientists for generations. But a new theory proposes that the fish use the earth's magnetic field to locate their origins in Scottish rivers.
Scientists believe that, in a process called "natal honing", salmon imprint the magnetic signature of their home once reaching adulthood...
The Earth's magnetic field varies across the globe each oceanic region has a different magnetic signature. Researchers believe that by remembering the unique "magnetic address" of their birthplace, fish may be able to distinguish that location from all others.
Salmon and sea turtles often bypass suitable breeding grounds on their vast journeys in favour of the places they were born. Scientists believe the fish do this due to previous breeding success at a particular site...
Scientists agree the Earth's magnetic field changes over time and probably helps animals arrive only in the general area of their birthplace. Then, once an animal is close to their target, other senses, such as vision or smell, may be used. Salmon are known to use their sense of smell to locate spawning grounds once they are close.
(Excerpt) Read more at martinfrost.ws ...
Do Salmon Navigate by the Earth’s Magnetic Field?
Alaska Science Forum
by Larry Gedney
November 23, 1984
Magnetic north pole shift: NASA and Egyptians say this has happened before
Bacteria which sense the Earth’s magnetic field (”Simple” organisms?)
EurekAlert! | November 20, 2005 | Staff
Posted on 11/22/2005 2:15:15 PM PST by DaveLoneRanger
|GGG managers are SunkenCiv, StayAt HomeMother & Ernest_at_the_Beach|
Just adding to the catalog, not sending a general distribution.
Wonder what it is that Leeds them back.
Haggis we’ll never know for sure.
I think the bigger puzzle is how do they find there way to Norway and Greenland?
They can be imprinted on their journey with the route they took but they have never been to the feeding grounds before.
On a trip to Scotland last year my party walked across a bridge and observed salmon going/jumping back up a river. Don’t ask me what river.
FYI, PBS is currently running a superb series on volcanoes. A recent episode dealt with how certain Alaskan salmon adapted some 2000 y ears ago, when a volcano erupted and completely blocked their access to the rivers and streams where they spawned. They were somehow, immediately able to modify their behavior. The episode should be on the PBS website.
The Royal Mail?
I have thought about the salmon's journey for years without arriving at your now-obvious question. Nice work.
A corollary of your question is “Why do hatchery raised salmon mingle with returning wild salmon since the hatchers have never experienced the birth stream of the wilds?”
Monarch butterfly migrations are also a wonder. Several generations are involved with the total trip.
A sixth sense that humans have lost or never needed
I’m irresistably attracted to the smell of pizza... :’)
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