Whale stranding, i.e. the accidental emergence of a whale on a beach, can have many reasons. Disturbances of the magnetic sense due to natural anomalies in the earth’s magnetic field have long been suspected. For the first time, scientists have now been able to prove that the whales not only receive incorrect information from the changed magnetic field, but that their senses often fail completely. Researchers at Duke University in North Carolina have now found that solar storms not only impair the sense of direction of gray whales, but also massively restrict it — the whales literally “go blind”. Study author Jesse Granger of Duke University said: “The whales strand much more frequently in solar storms because they simply go blind.” In their study, the researchers examined 186 stranding of gray whales (Eschrichtius robustus). It was found that stranding more than doubled on days with a high number of sunspots.
What effects can solar storms have on earth?
The earth is largely protected from solar storms by its atmosphere and magnetic field. This guides incoming, charged particles at a distance of about ten earth radii (70,000 kilometers) around the earth. In addition, the atmosphere shields the earth’s surface. At high altitudes and in the polar regions, where the field lines of the magnetic field are more inclined towards the earth’s surface, this protection is weaker. These regions are therefore more susceptible to the effects of solar storms.
What do solar storms have to do with the activity of the sun?
The sun is a very dynamic star: phases of increasing activity alternate with phases of decreasing activity. A measure of the sun’s activity is, for example, the number of dark sunspots that appear on its visible surface. When the sun is particularly active, these areas are particularly numerous. In times of high solar activity there are particularly many and particularly violent solar storms. Solar storms — even very strong ones — can, however, occasionally occur even when the activity is minimal.
Local magnetic field disturbances make gray whales blind
Gray whales orient themselves on the earth’s magnetic field by memorizing local natural disturbances or anomalies in the earth’s magnetic field and using them as a guide. These natural anomalies are strong and local changes and are largely stable. The whales can use these mountains and valleys to orient themselves in the magnetic field. If the local magnetic field changes due to a solar storm, the whales are almost blind and stranding occurs. “But we were able to show that the whales do not just get wrong information from the changed magnetic field, but that their senses often fail completely.” This is so drastic that many gray whales pay with their lives. Solar storms also generate high-frequency noise, which in turn overrides the magnetic orientation of the whales — i.e. their inner compass. However, this is not only the case during solar storms: the medium-frequency sonars commonly used in shipping also lead to stranding of gray whales. Study author Granger now wants to investigate the consequences of solar storms for other whale species. It’s not just about why the whales are stranded. The researchers are also interested in how exactly the animals’ magnetic sense works. To date, marine researchers know little about the sensitive organ of marine mammals.