Sometimes whales do strange things: they beach themselves, resulting in their own deaths. Although the reason for this odd and suicidal behavior is still unknown – and the whales are searched for injury or illness following the beaching – a team of whale researchers may be closer to the answer, and it sure is surprising.
The Gray Whale
Gray whales (Eschrichtius robustus) are found within the North Pacific Ocean, and are classified as Least Concern on the IUCN Red List. They are known for their high intellect and curiosity towards boats, making them an excellent focal point for whale watching and ecotourism tours along the west coast of North America. These whales can grow up to 49 feet long, and they have a mottled gray body with no dorsal fin – instead, they have a dorsal hump with small bumps, called “knuckles” between the dorsal hump and their tail flukes.
They are baleen whales, meaning they do not have teeth, and are primarily bottom feeders. They feed on sea-floor invertebrates by rolling to their sides and swimming along the sea bed, churning up sediment which is filtered through their baleen plates.
Due to their curiosity of boats, they are threatened by entanglement in fishing gear, vessel strikes and collisions, and also disturbance from whale watching activities. Gray whales undertake a massive migration along the west coast of North America each year, when they travel between Alaska and Mexico. They therefore depend strongly on their navigational abilities to find their way, so why are they becoming stranded along the west coast?
Why Are Whales Becoming Stranded?
In the past, researchers have suspected that whales are getting stranded on beaches due to a combination of disease, starvation, naval sonar, and seismic air guns used for oil exploration. In 2019, it was declared by NOAA Fisheries that the unusual increase in strandings of gray whales along the West Coast of America is an ‘Unusual Mortality Event’, and provided additional resources to respond to the strandings, as well as to focus scientific investigation into the causes.
Whale biologists are convinced that whales have an internal compass, which tells them where to travel during breeding and calving season, allowing them to navigate using Earth’s magnetic fields. This means that in theory, whales would be susceptible to geomagnetic space storms, which shifts magnetic field lines, confusing whales and throwing them off course.
However, a new study done by researchers from Duke University, North Carolina, USA, and the Adler Planetarium, Chicago, USA have discovered that this is not the case, and that strandings by gray whales were unrelated to geomagnetic activity. They published their surprising findings in the journal Current Biology.
During periods where the sun has high solar activity, it emits bursts of broadband radio energy. This has been witnessed by radio operators who suddenly hear a roar of static after a strong solar flare. Solar storms, or periods of high solar activity also known as geomagnetic storms, occur when the sun releases a burst of intense radiation and charged particles. These occurrences mess with the Earth’s magnetosphere, which usually deflects most of what the sun is emitting. However, intense solar storms can impact Earth’s magnetic field, causing disruptions to radio communications and GPS satellites.
Although it was always thought that gray whales migrate by sight, scientists suspected they could also use magnetism to find their way through Earth’s oceans.
The researchers of the new study looked at 31 years of gray whale stranding data (186 stranding events) compiled by the National Oceanic and Atmospheric Administration (NOAA) and correlated the strandings with indices of solar activity over the same period of time, including sunspot number, radio noise and geomagnetic activity.
The studied strandings included in the research were only when there was no injury, illness or starvation which may have caused the stranding. According to the correlations, there was a 4.3-fold increase in the likelihood of a gray whale stranding on days with high levels of 2800 MHz radio emissions. On the other hand, there was no relationship between the whale strandings and high levels of geomagnetic activity.
Whales and Magnetic Fields
These results are crucial, as it partly suggests exactly how gray whales (and potentially other whale species) are sensing magnetic fields.
One theory explaining magnetoreception in animals is the radical pair mechanism: a chemical compass in which magnetic fields regulate the chemical reaction involving proteins. In birds, this process occurs in the eye. This chemical reaction can be disrupted by radio frequency fields, meaning if whales utilize this mechanism for direction, it could explain why whales were at greater risk of being stranded shortly after a solar flare which releases radio energy.
The researchers hypothesize that the increased radio frequencies following a solar flare is not “throwing off” the whales’ internal compass, but rather that the sudden burst of frequencies overwhelms the system, shutting off the navigational system altogether, resulting in confusion and stranding.
The Impacts Of The Study
The new research into the reasons why gray whales (and possibly other whale species) strand themselves could potentially be life saving for whales. Stranded whales rarely survive the ordeal, unless help gets to them early enough to re-float them. Using the correlation between solar flares and strandings, researchers may be better able to predict when strandings may occur, and stranding networks could be more active during those periods.
Further research is still needed on how whales use Earth’s magnetic fields to navigate, as studies into whether an animal can sense magnetic fields are usually done within a controlled environment, such as within an enclosed area. The magnetic field the test subject is exposed to can be changed, and the reaction of the animal is observed.
With whales, a study into their ability to detect and use magnetic fields would not be so simple due to their sheer size. The researchers of the study acknowledge that their results do not definitively prove that whales use the radical pair mechanism and magnetoreception sensors to navigate, however it does indicate that gray whales are dependent on some sort of magnetic sense for their impressive navigational abilities.