Zuisho Maru 38 was captured January 21, off Kunashiri Island, one of the four disputed Kuril islands, allegedly carrying over 1.5 metric tons of fish, including cod, Alaska pollack and flounder, while the crew did not have a permit to fish in the 3-mile territorial zone.
"The captain of the boat agreed with the evidence proving the illegality of fishing in Russia's territorial waters, admitted to his wrongdoing, and asked to review the case without a court trial," a spokesperson for the South Kuril Islands prosecutors office said.
Prosecutors said a preliminary investigation against the captain and owner of the trawler, Kawabata Takashi, started on February 1, and he remained in custody while other five members of the crew had been released.
There have been frequent seizures of Japanese fishing boats in recent months as Russian Coast Guard authorities have stepped up patrols around the disputed territory.
An incident in August last year near the Kuril Islands, some of which are claimed by both Russia and Japan, led to the death of a Japanese fisherman, who was killed when Russian border guards fired warning shots when the ship refused to stop.
Russian officials said the Japanese vessel was suspected of illegally fishing for valuable crab in Russian territorial waters, and that border guards had fired warning shots only after it had refused to stop.
The incident strained relations between Russia and Japan, who have contested the ownership of the Kurils for over 60 years. Japan maintains that their seizure by the Soviet Union at the end of World War II was illegal, and the dispute has until now kept the two countries from signing a formal peace treaty.
