The latest string of stranded sperm whales in the North Sea occurred between Jan. 8 and Feb. 3, 2016. A total of 29 male whales were found beached along the coasts of German, the Netherlands, Great Britain and France.

Autopsies on 22 of the whales determined they were all in good nutritional health and didn’t suffer from any lethal diseases.

Sporadic sperm whale strandings have been documented in the North Sea since the Middle Ages, but the latest occurrence prompted a group of researchers to question why some whales deviate from their traditional migration route and end up in the shallow sea.

The team’s findings point toward solar storms and their geomagnetic anomalies as a possible culprit.

Male sperm whales spend their younger, non-breeding years at lower latitudes where magnetic disruptions by the sun are weak. The males don’t experience geomagnetic anomalies from solar storms until they are older, when they leave females and their young to form “bachelor groups” in the Norwegian Sea, where squid – their choice of prey – are abundant.

The study authors believe that “naïve” whales get distorted by the disruptions when they enter the Norwegian Sea and accidently end up in the shallower waters of the North Sea.

The timeline of reports of the stranded whales in January-February 2016 correspond with two solar storms recorded at the end of December 2015 and beginning of January 2016. They lasted 18 hours and 28 hours, respectively. They also produced auroras over northern Europe.

Sperm whale aren’t typically seen in the North Sea because the waters are shallow and the area lacks the whales’ favorite meal – squid.

But the solar storms could have interfered with the whales’ magnetic navigation system, according to the researchers. It is believed that cetaceans, which include whales and dolphins, navigate using magnetoreception – similar to birds and bats.

The storms created disturbances in Earth’s magnetic field, which may have been strong enough to trigger navigational errors and disorientation in the whales.

The study cited previous research with homing pigeons, which found that the birds experienced issues with orientation when they flew across an unknown area with large geomagnetic anomalies. Another study on honey bees found that on days with geomagnetic storms, there was a 2.7 times greater loss of incoming to outgoing bees to a hive, compared to days without storms. The greatest bee losses occurred during the longest and most severe storms.

The male sperm whales may be experiencing similar effects, causing them to accidently travel into the North Sea.

“If they (the whales) do not compensate by switching from their magnetic sense to an alternative mode of navigation (only few navigation systems can be used in the deep sea such as bathymetry or the Sun), they may become stranded along the shallow and tidally influenced North Sea coasts, after continuing to misguidedly swim south for a week or more,” wrote the study authors.

The findings have been published in the International Journal of Astrobiology.