A Japanese Coast Guard official, Kazuhiro Nakaya, is quoted as saying the man was shot as the Russian patrol captured his crab-fishing boat near a group of islands, known as the Northern Territories in Japan and the Southern Kuriles in Russia, claimed by both Japan and Russia.
Russia's Federal Security Service (FSB) says the Japanese vessel repeatedly ignored warnings to stop. Three tons of illegally harvested crab and octopus were found on the vessel, which has been impounded.
Jinen Nagase, Japan's deputy chief cabinet secretary, described the incident as "regrettable," and the Japanese authorities have demanded the release of the fishermen and their ship.
The Russian Foreign Ministry has also expressed its regret at the death.
Russia's deputy foreign minister, Aleksandr Alekseyev, met with the Japanese ambassador to Russia, Yasuo Saito.
Alekseyev said after the talks that there was "no need to dramatize the situation," and called on Japan to curb poaching in Russian waters.
(Interfax, ITAR-TASS, AFP, Reuters)