The elephant population in Tanzania, beset by poaching for ivory, has plummeted by two-thirds in the past three-and-a-half decades, the government said on Saturday. The findings are the result of a census carried out at the end of last year in the country's parks and reserves with the largest elephant herds, Lazaro Nyalandu, junior minister for natural resources and tourism, said in a statement. "Results in Selous, Mikumi, Ruaha and Ruangwa eco-system show a drop of 66 percent in the population of elephants between 1976 and last year," Nyalandu said. "The Selous-Mikumi ecosystem had 109,419 elephants in 1976, but the number has gone to 13,084 now. This is very serious," the minister noted. Wildlife safaris -- often combined with a beach holiday on Tanzania's Indian Ocean coast -- are a major source of foreign currency for the east African country. In October police and wildlife officers started a crackdown on suspected poachers amid a surge of killings of elephant and rhino, operating under what was reported to be a shoot-to-kill policy and making sweeping arrests. Members of the security forces taking part were accused of numerous killings, incidents of torture and rapes, prompting the government to halt the anti-poaching drive in November and sack four key ministers in December. The draconian operation did result in a sharp decline in poaching. "During the entire period of the operation only two elephants were reportedly killed, while 60 were butchered between November 1 and December 28," Nyalandu said at the end of last month. The anti-poaching operation -- code named Operation Tokomeza or operation Terminate -- will resume, Nyalandu said, without giving any date and emphasizing that this time around all officials involved will have to abide by a code of conduct. Poaching has risen sharply in Africa in recent years. Besides targeting rhinos, poachers have massacred whole herds of elephants for their ivory.