Water temperatures may have a role, experts said.
Oarfish more than 13 feet long and giant squid with massive tentacles, deep-sea creatures whose biology is long cloaked in mystery, have been found one after another along the Sea of Japan since the beginning of the year. Experts believe a change in sea temperature has some effect, but the cause remains unknown.
“It was weak but still alive. It spewed water as if exhaling heavily,” Yuji Kawaguchi, 65, a fisherman in Sado, Niigata Prefecture, said about his surprising encounter with a giant squid that got caught in his fixed fishing net about 330 meters off the coast of Ryotsu Bay, Sado Island, in late March.
The giant squid was more than 14 feet long and weighed more than 70 pounds.
Eight giant squids have been found in waters off Niigata Prefecture this year. According to a local curator, only about 11 giant squids have been identified over five decades — until last year.
And it’s not just giant squids. A 8.5-foot-long razorback scabbardfish was caught in a fishing net in March. According to the Uozu Aquarium in Toyama Prefecture, razorback scabbardfish have not been found in the bay since 1990.
Three scalloped ribbonfish of a type not caught for nearly 20 years in Toyama Bay were also found this year.
Even deep-water fish, such as giant oarfish and slender ribbonfish, have been found.
Hiroyuki Hamazumi, a counselor at the Uozu Fisheries Cooperative, expressed his opinion that the reports increased after giant squids were introduced to the public on TV programs.
Although there is speculation that the string of deep-water-creature finds is a sign of an upcoming earthquake, experts presume that the structure of the Japan Sea and change in sea temperature have something to do with it.
In the deep waters of the Sea of Japan, which is shaped like a basin, there is a zone where cold water from the continent accumulates. The temperature around 200 meters, or 656 feet, below the surface was about 1 degree lower than the average this winter, meaning that an extremely high-impact change occurred in the deep ocean, said the Sea of Japan Marine Meterological Center.
Although the reason for the temperature drop is unclear, Kunio Amaoka, a professor emeritus at Hokkaido University, points out that this change made the cold water zone in deep waters larger than usual.
The professor’s perspective is that because deep-water creatures have poor muscle development and are not good swimmers, they cannot escape from the larger-than-usual cold water zone when they run into it. They then become weak and float up, before being swept to waters near the shore.