Unprecedented Mass Fish Mortality in Northern Japan: A Silver Blanket of Sardines and Mackerel

By: | December 15th, 2023

Thousands of dead sardines were found ashore on an island in Japan (Image by Wikimedia Commons)

Enigma on a Northern Japan Shoreline

Hundreds of tons of dead sardines and mackerel have washed up on a beach in northern Japan, creating a silver blanket along a 1.5-kilometer stretch near the Toi fishing port in southern Hakodate, Hokkaido. Residents in the area were surprised by the unprecedented sight of tons of dead fish washing ashore.

The estimated landing on December 7 comprised at least 1,000 tons, predominantly sardines but also including some mackerel. However, there are concerns that the actual figure may surpass this initial assessment. The Hakodate city government is actively investigating the cause of this mass fish mortality and is formulating plans for their removal.

Local officials, upon discovering substantial quantities of deceased fish, promptly issued warnings to the public against consuming them. Despite a town notice advising against it, residents in the area collected the fish for sale or consumption.

Scientific Perspective

The authorities have yet to pinpoint a specific cause for the substantial sardine mortality. Nonetheless, Takashi Fujioka, a researcher at the Hakodate Fisheries Research Institute, has acknowledged that while he has heard of similar incidents before, this marks his first direct observation of such an event.

According to Japan Today, the mass fish mortality in Hakodate, Hokkaido, might be due to larger predators chasing the densely packed school, causing exhaustion and oxygen depletion. Another possibility is abrupt changes in water temperature during their migration. The incident involved a group of sardines and mackerel washing ashore, covering nearly a one-kilometer stretch of the beach like a thin blanket.

Nidhi Goyal

Nidhi is a gold medalist Post Graduate in Atmospheric and Oceanic Sciences.

More articles from Industry Tap...