The trawler, the Diasan Shinsho-maru, capsized off Chiba`as its three-man crew was trying to haul in a net containing dozens of huge Nomura’s jellyfish.
Each of the jellyfish can weigh up to 200 kg and waters around Japan have been inundated with the creatures this year. Experts believe weather and water conditions in the breeding grounds, off the coast of China, have been ideal for the jellyfish in recent months.
The crew of the fishing boat was thrown into the sea when the vessel capsized, but the three men were rescued by another trawler, according to the Mainichi newspaper. The local Coast Guard office reported that the weather was clear and the sea was calm at the time of the accident.
One of the largest jellyfish in the world, the species can grow up to 2 meters in diameter. The last time Japan was invaded on a similar scale, in the summer of 2005, the jellyfish damaged nets, rendered fish inedible with their toxic stings and even caused injuries to fishermen.
Relatively little is known about Nomura’s jellyfish, such as why some years see thousands of the creatures floating across the Sea of Japan on the Tsushima Current, but last year there were virtually no sightings. In 2007, there were 15,500 reports of damage to fishing equipment caused by the creatures.
Experts believe that one contributing factor to the jellyfish becoming more frequent visitors to Japanese waters may be a decline in the number of predators, which include sea turtles and certain species of fish.