Researchers say this year’s record poor catches of shrimp and crabs in Toyama Bay could be due to undersea landslides triggered by the powerful earthquake that struck central Japan on New Year’s Day.
Toyama Bay is fed by groundwater from a nearby mountain range and deepens sharply to a depth of more than 1,000 meters. It is known to harbor bountiful marine life, including broad velvet shrimp, red snow crabs, yellowtail and firefly squid.
The shrimp in particular is cherished as the “jewel of Toyama Bay.” The Fisheries Research Institute in Toyama Prefecture says catches of the shrimp stood at 118 tons for the six months from April. That’s just 27 percent of an average year, and a record low for the period.
Catches of red snow crabs similarly fell to an all-time low. Fishers hauled in 107 tons in the January-May period, or 58 percent of an average year. They’re also seeing record poor catches in the new season that began in September.
A survey by the Japan Coast Guard showed that the Noto Peninsula earthquake caused a seabed slope in Toyama Bay to collapse over an area measuring about 3.5 kilometers by one kilometer, to a depth of up to around 40 meters.
The Fisheries Research Institute has also confirmed from undersea footage traces of landslides at four or five locations. It says excessive amounts of sulfide detrimental to marine life have been detected in the soil at more locations since the earthquake.
The researchers say the broad velvet shrimp and red snow crabs may have been caught up in the landslides, or could have died or migrated due to the sulfide spewing from areas exposed by the landslides.
The researchers expect it to take two or three years for shrimp stocks to recover due to a decline in the concentration of the juvenile population compared to pre-quake levels.
They say more than nine years will likely be required for the red snow crabs, as habitat concentrations of male, female and young crabs have all decreased.