“My view is that the US trade [in hippo parts] is largely a byproduct of other reasons for killing,” says Crawford Allan, a wildlife trade expert with the World Wildlife Fund. In Africa, he says, “nobody wastes anything. So if you kill an animal because it’s a danger to your community, then you eat the meat, you sell the skin, you sell the teeth, you sell the skull to taxidermy collectors.” Hippo parts like teeth and skin, he says, are not worth enough to local hunters to provide an important reason for killing them.

Other experts echo this opinion. Lewison cites the example of Virunga National Park in the Democratic Republic of the Congo, where the hippo population declined from almost 30,000 in the mid-1970s to fewer than 1,000 by 2005. The animals were killed during civil unrest and war “when everyone was starving. And they ate them.”

Lewison acknowledges that hippo parts are sometimes found in seizures of trafficked wildlife products, but she says that they form a tiny part of the illegal wildlife trade, which is sustained by far more valuable products, like elephant ivory and rhino horn.

An analysis of official trade numbers by HSI and its collaborators showed that, of the hippo products imported to the US between 2008 and 2019, 2,074 were hunting trophies. (Other nations legally imported roughly 2,000 more hippo trophies during the same period). However, a trade database compiled by the Convention on International Trade in Endangered Species of Wild Fauna and Flora reveals that virtually all the trophies and other hippo parts tabulated by the HSI came from countries with large, apparently well-managed hippo populations. Neither HSI nor the Center for Biological Diversity provided any data that linked hunting trophies or other legally traded parts to hippo declines.

Paul Scholte, an Ethiopia-based member of the Hippo Specialist Group, says that regulated trophy hunting can have conservation benefits. With local colleagues, he conducted and published surveys of hippo populations in northern Cameroon that show declines in government-run conservation areas and either stable or increasing populations in areas leased by private trophy-hunting outfitters.

“The factor that explains if a population of hippo is stable or not is a year-round presence of protection—of rangers or scouts,” Scholte says, explaining that government rangers do not patrol during much of the rainy season, when moving around is difficult. Trophy-hunting companies, however, have the funding and motivation to continuously protect their concession areas from the poachers and illegal gold miners who kill hippos in that region.

Hippo experts say the focus on the parts trade is a distraction from more important issues and that it escalates friction between African countries. They point out that southern and eastern African countries—which have larger and better-managed conservation areas—generally host more secure hippo populations than do countries in Central and West Africa, where many populations are on the brink of extirpation.

These varying circumstances lead to different views on conservation policy: West and Central African authorities generally favor wildlife trade bans, which they believe would discourage poaching of their extremely vulnerable populations, while most countries in southern Africa and some in East Africa argue that their populations are large enough to sustain hunting and commercial trade, which fund wildlife conservation.