in the late 1940s, roughly 9,000 north korean migrant workers were recruited by the soviet government to work in state-owned fisheries on sakhalin. another 25,000 workers also came to work in fisheries during the 1950s. the second wave, which began in 1966 or 1967 under a secret agreement between leonid brezhnev and kim il-sung in vladivostok, involved north koreans working as lumberjacks. roughly 15,000 to 20,000 were present in any given year. the first two waves consisted mostly of criminals or political prisoners.