The residents of Hakodate, a port city on the southern tip of Hokkaido, woke up to the alarming site of thousands upon thousands of dead fish lining the shores late last week. 

The fish, comprised mostly of sardines and mackerel, covered a stretch of beach about half a mile long, creating what is being called a ‘silver blanket’ across the vast area. 

The unusual site certainly caused a concerned reaction across the country, although not enough for many local residents, as they proceeded to collect many of the fish intending to eat or sell them later — despite a warning from government officials to not do either of those things. This is primarily due to the reason behind the incident not being entirely clear; investigations are currently ongoing.

Took a look for yourself via a video posted by Associated Press

The timing of the incident is sparking some theories that the release of treated Fukushima water — a process that started nearly three months ago — is to blame, however there is currently little evidence to support this. 

Currently several other reasons have been put forward as a cause including a larger school of fish chasing (this) smaller school of fish into shallower waters. Others suggest it could be related to excessive cold water and subsequent shock. The more likely explanation stated so far is the possibility of a climate related scenario. 

Earlier this year a similar occurrence took place in Texas (Smithsonian magazine) where huge amounts of fish washed up on beaches there too. The consensus in that case was the presence of warmer waters which depletes oxygen levels especially in shallower waters. 

It’s very plausible that something similar has occurred with this recent case in Hakodate, but unless it truly is Fukushima water poisoning (which it likely isn’t) we may never know the reason for sure.