The discovery of growing numbers of colossal oarfish in fishermens’ nets in Japan have raised fears of an impending natural disaster as the appearance of the usually deep-sea-dwelling species has long been considered a harbinger of earthquakes and tsunamis.

One specimen measuring just under 4m was accidentally caught in a fixed net about 1km off Imizu, in Toyama Bay, off Japan’s north coast, on Monday.

At least three others have been found over the past week, and two were found earlier in January.

According to the Uozu Aquarium in Toyama bay the first confirmed oarfish sighting in the area came in 2009, since then 20 have been found with four of those in 2015.

The appearance of the distinctive species, which is distinguished by a long silvery body and red fins, has reportedly left marine biologists perplexed. Oarfish are a relatively rare bycatch, as they live between 200m and 1,000m (650ft to 3,200ft) below the surface.

Endangered sharks being served up in British fish and chip shops Show all 6 1 /6 Endangered sharks being served up in British fish and chip shops Endangered sharks being served up in British fish and chip shops Scalloped hammerhead shark Scalloped hammerhead shark fins were among those found being sold by an Asian food retailer in the UK. These sharks are endangered, and in parts of the Atlantic Ocean, their populations have declined by over 95% in the past 30 years. Istock/Janos Endangered sharks being served up in British fish and chip shops Spiny dogfish In the samples of takeaway fish and chips sampled, spiny dogfish made up 90% of those sold under the names huss, rock salmon and rock eel. Doug Costa, NOAA/SBNMS Endangered sharks being served up in British fish and chip shops Shortfin mako shark Another vulnerable species found in the dried shark fins tested in the British Asian wholefood retailer was the shortfin mako shark. Istock/Alessandro De Maddalena Endangered sharks being served up in British fish and chip shops Blue shark Blue shark was also found on sale in UK shops. This species is not as vulnerable as the others but is still listed as "Near Threatened" by the International Union for Conservation of Nature Istock/Howard Chen Endangered sharks being served up in British fish and chip shops Nursehound Around a quarter of the sharks being sold in UK fishmongers were nursehounds, another relatively safe species that is nevertheless classified as near threatened. Mario Antonio Pena Zapatería Endangered sharks being served up in British fish and chip shops Misleading names in fish shops The scientists behind the study investigating the prevalence of endangered shark meat on sale concluded that shops must stop selling these species under "umbrella terms" that hide their true origin. Istock

But finding several of the creatures, which are known as “Ryugu no tsukai” in Japanese, or the “Messenger from the Sea God’s Palace,” has long been believed to be an omen of natural disasters including earthquakes and tsunamis.

According to the region’s Fisheries Research Institute, the water temperature at the surface in Toyama Bay is several degrees higher than average, while at deeper depths – between 200m and 300m, the water is cooler than usual.

Speaking to the Straits Times, Satoshi Kusama of Uozo Aquarium said: “[Finding several in a row] is said to be the forerunner of an earthquake or to be influenced by ocean temperatures, but research is scarce and we don’t know the cause.”

The myth that sightings of the fish are a forerunner to disaster gained currency following the 2011 Fukushima earthquake and tsunami, when more than a dozen oarfish washed up in the preceding year, the Japan Times reports.

Yoshiaki Kai, assistant professor at Kyoto University’s Maizuru Fisheries Research Station, told the paper: “I have never heard of so many of them coming up like this. There have been occurrences of fishermen releasing them into the sea after catching them in stationary nets because they couldn’t sell them on the market.”

Support free-thinking journalism and attend Independent events

Support free-thinking journalism and subscribe to Independent Minds