The move has been prompted by the stepped-up illegal efforts to catch crab that the poachers supply to Japan, South Korea and China, according to the Russian Border-Guard Service.
Two Cambodian trawlers were detained in the Russian waters near Sakhalin Island last Friday.
Russian border-guards let back into the sea more than two tons of live crabs from one of the trawlers.
A total of 500 tons of fish and crab has been returned to the sea from poaching ships near Sakhalin since early this year.
Voice of Russia, TASS