For the first time in decades, hunters with deep pockets cannot target the so-called "Big 5" game animals in South Africa because the government has imposed a ban on leopard hunts for the 2016 season.

The temporary ban comes in the wake of a global uproar last year over the killing of Cecil the Lion in Zimbabwe by a US dentist.

The decision, however, was driven by science, not emotion. South African Environment Minister Edna Molewa is a vocal advocate of the hunting industry, which the government estimates contributes 6.2 billion rand ($410 million) annually to Africa's most advanced economy.

Leopard is one of the Big 5 game most desired by hunters, along with lion, rhino, buffalo and elephant.

The South African National Biodiversity Institute, a government research organisation, recommended the temporary ban because it said leopard numbers could not be firmly established.

"There is uncertainty about the numbers and this is not a permanent ban, but we need more information to guide quotas," said John Donaldson, the institute's director of research.

Given their secretive and nocturnal nature, leopards are not easy to count.

The institute drew on studies and data from a number of sources but Donaldson said most was from protected areas and national parks, not private lands.

The Professional Hunters Association of South Africa (PHASA) says this gives an incomplete picture.

"There are lots of leopards on private land," said PHASA chief executive Tharia Unwin.

Hunting all of the Big 5 has been legal in South Africa since the 1980s when hunts for white rhino were resumed.