A pair of hippos swim in the waters of St Lucia estuary, South Africa, April 12, 2006. REUTERS/Mike Hutchings/File Photo

LUSAKA (Reuters) - Zambian wildlife authorities said on Tuesday they had suspended the controlled slaughter of up to 2,000 hippos over the next five years following concerns from animal rights activists who described it as trophy hunting.

Zambia’s Department of National Parks and Wildlife said it started the hippo culling after new research showed that the water levels in Luangwa river were “low and insufficient to support the hippo population, especially in the dry season.”

Zambia has between 42,000 and 50,000 hippos, a population the Department of National Parks and Wildlife says cannot be supported by the water levels in the Luangwa valley where most of the animals are located.

British wildlife charity Born Free said on its web site that the scientific rationale for killing up to 2,000 hippos when their population in the entire southern Africa region stood at 80,000 hippos was questionable.

“I urge the authorities to call a halt to the killing with immediate effect,” Born Free President and Co-Founder, Will Travers said in a post on the charity’s website.

Water levels in Zambia’s rivers and lakes have dropped following a prolonged drought that threatens crops across the Southern African region where the United Nations has warned that 14 million people face hunger.