Salmon navigation

Foxsea

Well-Known Member
The fish travel hundreds of thousands of kilometres through the ocean and then fight the current swimming upstream to spawn — and die — in the same fresh water where they hatched.

The juvenile salmon then make the same journey in reverse to find the ocean foraging grounds of their forebears.

"Given that the animals have never been there before, how do they find their way?" asks Nathan Putman, a biologist at the Department of Fisheries and Wildlife at Oregon State University and lead author of a new study that may have the answer.

It's been a widely held belief that ocean current delivers the salmon to these spots, but Putman and his colleagues found that doesn't appear to be the case.

"While this can certainly help in some situations, more recent studies suggest that it isn't entirely reliable," he says in an email.

A study by the same researchers last year on B.C. salmon in the Fraser River suggested adults used the magnetic field to find home.

more at: http://www.cbc.ca/news/technology/young-salmon-navigate-with-built-in-magnetic-compass-1.2525934
 
That's amasing! Very cool article.Makes perfect sense that they would need some sort of built in GPS to get them there
and back again. Thanks for that,Foxsea.
 
Actually, the concept is not that new.

Back in the 70's, the US Dept of Energy was prospecting on ways to derive electricity from oceans currents. The plan was to install devices that would be activated by ocean currents in order to produce power,much like wind mill farms- only using ocean currents as a generating force.

But, the committee needed to know how this would affect migrating species of fish. As it turned out, it would be a disaster due to electromagnetic fields generated would cause disorientation. How this came to be known was with the help of the Pacific Biological Station in Nanaimo. They became active in this back in 1987-1988.

Fish, when hatched have single-domain cells of magnetite. As adults, an orderly pattern of growth is referred to as multi-domain cells.

The National Academy of Sciences:, "The cells were observed to rotate at the same frequency as the driving frequency of the external magnetic field."

Simply put, fish, as with other migrating species, follow certain magnetic paths with no profound sense of where or why. When they reach maturity, the compass kicks in they have no choice but to follow the magnetic fields. This was proven by the California Institute of Technology. They performed rigid testing of all species of salmon with particular interest in adult specimens of sockeye and chinook. Of course salmon species were not the only ones tested as they tested many species.

I will not provide the particulars of the tests such as how the tests were done or what specific magnets were used, polarity inversions, Gauss units, N factors, effects of N factors under water and in salt water, waters ability to be repelled by magnetic forces, compensating for repellency, climate effects, spacing and so forth. The reason being that I spent many years collecting data, stats, charts, results and whatnot, plus I used my formal education of electromagnetics, physics and wildlife and marine biology to build, and market, magnetic lures through Pirates Den Fishing. I have patents pending on the designs so obviously my research and results a well as specifics are trade secrets.

Another interesting note about magnets pertains to sharks. Many local anglers catch dogfish sharks. Some will release them while other kill them and throw the bodies back to the water. I reckon I am one of few that will eat them. That aside, many species of sharks are repelled by magnetic forces. Apparently, it screws up their internal compass and interferes with the electro sensors sharks use to locate food. In recent years, several companies started building dive suits with magnets built in.

A magnetic lure helps to repel sharks, this saving bait for the fish the magnetic field brings in. I will not say it repels all sharks. Some, it appears, are more resistant to the field. In tests conducted by the Washington State Dept of Fish and Wildlife did studies of varying Br values of magnets and spiny dogfish sharks back in 1997. Using magnets of lower Br, found a decrease in shark catch incidents and the higher the Br, the fewer incidents. This was interesting.

In order to build a productive lure, there must be a compromise in Br and N factors. Too strong, it runs off nearly everything, too weak and it will still run off most sharks, but not effective for catching fish.

If not for assistance from WDFW, PBS, USDE and some very helpful scientists in Canada, the US, Poland, Germany and Australia, this lure would have never been devised. I would also like to thank Telus for providing me some very expensive phone bills.

Magnetic testing verified positive results in controlled test labs for salmon, tuna, trout, bill fish, cobia, mahi and many others. Testing on other species is ongoing at this time. Research facilities in other countries are conducting tests as well for species indigenous to those specific locales.
 
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You are a Salty Dog! best synopsis I have read on the subject.. Thanks !!

beemer
 
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