After people deserted the towns, wild boars emerged from local forests to scavenge for food and, according to local media, have flourished.
The boars have been eating food and plants, which have caused the animals to be exposed to radiation levels far in excess of government stipulated safe levels.
Reports state that teams of hunters have been dispatched to cull the boars from the towns of Namie and Tomioka.
At the end of March, Japan is set to lift evacuation orders for parts of Namie, located just 2.5 miles from the wrecked nuclear plant, as well as three other towns.
Meanwhile, residents who do not return to homes not sited within mandatory exclusion zones are being told they risk losing housing benefits.
A Greenpeace report has said that of the 160,000 who fled their homes, 80,000 have yet to return.
The report accused the government of trying to minimize the impact of the disaster and that evacuees are being returned to areas with radioactive contamination at higher levels than internationally recommended safe levels.
"Many may be forced to return to contaminated communities against their wishes because they cannot afford to stay where they are currently living.
"This is economic coercion, not a choice freely made," the report reads.
The report has said that the Japanese government's response to the nuclear disaster "resulted in multiple human rights violations, particularly for women and children."