Even if researchers find the culprits, the impacts could reach further than suspected. “We really underestimated [the number of dead] crocodiles from last year’s count,” Govender adds, noting that their bodies could have been eaten by other crocs or sunk to the bottom of the river. “I suspect we’re losing a lot of breeding females,” whose carcasses are smaller and more easily scavenged. If that is the case, she says, the gorge’s crocodile population may not ever recover, even if scientists can pinpoint the cause of the die-off.
As for the people who depend on the Olifants River, “I don’t know what to tell them,” Bouwman says. His colleague Henrik Kylin of Swedish University of Agricultural Sciences in Uppsala wants to go into Mozambique to test fish there, and possibly people, to see if the croc killer kills more than just crocs.
Note: This article was originally printed with the title, "Hunting a Croc Killer."