OTSUCHI, Iwate Prefecture--The first survey of marine life living on the seabed after the Great East Japan Earthquake and tsunami showed a sharp drop in abalone and sea urchins.
OTSUCHI, Iwate Prefecture--The first survey of marine life living on the seabed after the Great East Japan Earthquake and tsunami showed a sharp drop in abalone and sea urchins.
The survey was conducted July 11 and 12 in Otsuchi Bay in Iwate Prefecture.
Tomohiko Kawamura, associate professor at the University of Tokyo's Atmosphere and Ocean Research Institute, led the research team.
"The numbers of sea urchins and abalone will recover in a few years because there's plenty of seaweed for them to eat," Kawamura said. "But I think fishing should be restrained this year."
The institute and the Fisheries Research Agency have jointly conducted fixed-point observations at a depth of 10 meters off Otsuchi four times a year for the last five years.
The survey counted creatures found within 2-meter square frames at eight locations.
The number of short-spined sea urchins plummeted from 44-52 last year to only two, while northern sea urchins dropped from 140-160 to 59, the survey found.
Only a few abalone with a length of 5 centimeters or less, which are 2 or 3 years old, were observed.
None of the young abalone that were released last year was found.
Since shellfish cannot anchor themselves as well as sea urchins to the seabed, they may have been washed away, researchers said.
In contrast, seaweed increased because there is less marine life in the area eating it.