Salmon's Homecoming with the Help of Magnetic Fields Experiment

Salmon's Homecoming with the Help of Magnetic Fields

Experiment

Pacific Salmons are capable of determining the location of their home river due to certain chemical signals; however how they navigate themselves back to the spawning location still remains unclear. Putnam et al. proposes that salmon are able to navigate to their home river because Pacific salmon can imprint on the magnetic fields. Putnam et al. analyzed a 56 year old fisheries data set from the International Pacific Salmon Fisheries Commission to recognize the routes the salmon use to return to their spawning location. The two routes used are the northern entrance, Queen Charlotte Strait, and the southern entrance, Strait of Juan de Fuca. With this information, the researchers compared it to the intensity of the magnetic field and temperatures.

Results

Pacific Salmon's routes were predicted by the geomagnetic fields, where they take the route depending on the intensity of the magnetic fields the salmon recognize before leaving the spawn location. For instance, if the Queen Charlotte Strait consists of similar magnetic intensity as the Fraser River Mouth, then more salmons will take this path, thus further increasing the diversion rate since more salmon will take this route than the other. However, geomagnetic fields alter by a little each year and that is the reason why salmons take different routes. Also, the researchers also find that it is not only one of the factors. Another factor is temperature as more fish enter the northern entrance during the year where the northern seas were warmer, therefore being constrained to northern latitudes.

Conclusion

The Pacific Salmon relies heavily on the intensity of the magnetic field and allowed the researchers to accurately predict their route with this information. The Pacific Salmon utilizes the magnetic intensity from when they have left the spawning location and return taking the route which had similar magnetic intensity since their departure.

What if?

What if the Pacific salmon could not imprint geomagnetic fields? Can they use other factors? Why or Why not?

Justification

The discovery of Pacific salmon being able to recognize the geomagnetic field and using it to navigate themselves further enhances the understanding of behavioral biology and evolution. Although some scientists already known that some species are sensitive to geomagnetic fields, such as sea turtles, birds and bats, however they do not know species like the Pacific Salmon could use it at such an extent where they can navigate back to their destination. Most scientists are likely to infer on how Pacific salmons are genetically programmed and inherited information of how to return,