Nuclear science points the way in rhino conservation

Larkin is head of the Rhisotope Project, which is developing a new concept for the conservation of endangered rhinoceros species in South Africa and other countries. Other members of the team are Russia's Rosatom, Australia's Ansto and South Africa's Necsa, Colorado State University, as well as leading rhino vet William Fowlds among others.

Together the Rhisotope Project partners are testing whether injecting harmless amounts of radioactive isotopes into the horns of living rhinos will make them unattractive to poachers by making them detectable when crossing international borders, as well as less desirable to buyers.

The project is at the proof-of-concept stage, having injected non-radioactive isotopes into the horns of two rhinos on the Buffalo Kloof game farm to make sure that they do not migrate to the main body of the rhino. The animals, Igor and Denver, were injected in May and still have a few weeks to go before measurements will be taken to determine the results. "It's not that easy to do a CT scan of a rhino head," said Larkin, "but fortunately there are one or two places in the world that we can do that."

A team at the University of Witwatersrand is creating a full size 3D printed rhino head so that Larkin can take confirmatory measurements of radiation doses at various places.

To be put into practice, radiation doses must be small enough to be no harm to the animals or the people that carry out the injections, yet they must be enough to set off radiation detection portals at national ports of entry. Another consideration would be the radiation dose to any port officials who discover an isotope-tagged horn. All this needs to be carefully estimated and verified to satisfy regulatory demands.

The next stage would be a trial with radioactive isotopes in 15 rhinos and a six-month observation period to ensure no ill effects compared to a control group of five other rhinos.

"I was sick and tired of seeing videos of these mutilated animals," said Larkin. "We always say 'somebody should do something about it', and I realised I could possibly be that person." The Rhisotope Project was then born from an idea which "had been on a piece of paper for a number of years." It builds on Larkin's experience in radiation protection gained in South Africa's gold mines as well as later work on nuclear security.

"If we can stop the end user wanting the horn then perhaps we have a chance of saving these animals," said Larkin, and by bringing many thousands of radiation monitors worldwide to bear, "we can radically increase the army of people" able to detect and stop the smuggling. "It's not a traditional conservation project, but I think the outcome will be successful."