Thousands of herring have floated ashore on Norway's western coast, leaving experts perplexed about the phenomenon, according to the Norwegian Institute of Marine Research.
Local media reported that some 20 tonnes of fish were found at the end of December on a beach in northern Norway.
"We have seen herring stranded before but never this much," biologist Ole Kristian Berg at the Norwegian University of Science and Technology in Trondheim told AFP.
Berg said the herring may have been chased up on land by other fish or other ocean mammals.
They may also have fallen victim to the tides or high levels of freshwater in the area, where a river flows into the ocean, he said.
According to the Nordreisa municipality, many of the fish have now been swept out to sea by the tides.
Explore further: Study on world's biggest animal finds more than one population in the southeastern Pacific