Tokyo: A Japanese research team has found eggs of natural Japanese eels in the Pacific Ocean off the Mariana Islands for the first time, providing answers to longtime mysteries of where and when the fish spawn, it said in the British science magazine Nature Communications issued on Tuesday.
The team led by Katsumi Tsukamoto, a researcher at the University of Tokyo`s Atmosphere and Oceanic Research Institute, said it collected 31 eel eggs near the West Mariana Ridge shortly before the new moon in May 2009.
Most eels, popularly eaten in Japan, are currently raised in farms using fry caught in the sea. But the team hopes the latest discovery will help enable eel farming from eggs and prevent further declines in the eel population.
Using a net for plankton in filtering seawater, the team found eel eggs, estimated to have been fertilized about 30 hours before, in a 10 kilometer-square area located south of the oceanic ridge.
The team also found newly hatched eel larvae concentrated at a depth of about 160 meters, leading them to believe spawning takes place at a depth of around 200 meters and the eggs gradually rise to the level.
Fifteen adult Japanese eels and giant mottled eels in spawning condition were also caught in the same area, they said.
In the study that began in the 1970s, the team first estimated the spawning area to be near seamounts and the spawning period to coincide with the new moon.
In 2005, they found larvae two days after hatching but were unsuccessful in finding the actual eggs.