As a bare minimum you are going to need an armoured breast plate to protect you,” one of my research associates said. I mulled the statement over for a minute. Perhaps, I thought. I was incredibly nervous about what we were proposing. The idea of tagging the world’s largest marine stingray, free-swimming in the wild, was intimidating to say the least. With massive stingers the size of a human forearm and the tail musculature needed to deploy it mid-water into anything that presents a threat, these rays can certainly defend themselves. As no one had ever tried to tag this species before, it was unclear how they would react.

I am a shark and ray expert. I have been researching different species in the field for more than 20 years. Along the way I have personally tagged more than 100 individual sharks and rays and I feel extremely comfortable doing so. I also have been working with this specific species of ray in the wild for years in Mozambique and have always found them to be docile, slow moving and relatively unperturbed of our presence. 

Known commonly as the smalleye stingray, these rays can reach up to ten feet in length and have extremely small eyes relative to their body size. They give the impression they can’t see very well – we often see them bumping into soft coral sea whips or sponges as they track around the inshore reefs to visit cleaning stations. In fact, when another species accidentally bumps into them, it seems to elicit a disproportionately strong response, almost as if they had not seen the animal at all. These observations were worrying as I was unsure how these specific rays might respond to me prodding them with my tagging pole. Different species of sharks and rays have wildly different responses to tagging. Whale sharks barely react. However, given the fact that they have the thickest skin of any animal, they simply may not feel it. Giant oceanic manta rays, on the other hand, know I have done something to them, but they often act like they are not bothered by it. An animal that feels like tagging is a threat to them might react by trying to defend itself. In the case of the smalleye stingray, this kind of reaction could result in them deploying their stinger.

The development of sophisticated animal-borne tags has been a gamechanger for marine researchers, particularly those of us needing to track rare, elusive or highly mobile species. We have learned so much about manta rays, whale sharks and marine predators like bull sharks by tagging them. Tagging a smalleye might be our best and only opportunity to learn more about one of the world’s rarest and most elusive species of rays – a species that has never been studied before, and is likely to be endangered. Given all that, the potential reward outweighed  the potential risk. 

We only discovered we had smalleye stingrays in Africa in 2008. Dr Simon Pierce, the other co-founder of the Marine Megafauna Foundation (MMF), and I had been regularly encountering a huge species of stingray that we were unfamiliar with on our deep reefs in southern Mozambique. After some sleuthing we determined it was an extremely rare species, occasionally seen in fisheries on the other side of the Indian Ocean. It was not known from Africa, and it turned out to be a whopping 5,000km range extension from the Maldives, the furthest west they had previously been seen in the Indian Ocean. We continued to encounter them regularly and it did not take us long to realise that we were sitting on the largest identified population in the world, and the only known location where they could be studied reliably.

Fast forward a decade and we were now faced with the daunting challenge of tagging some representative individuals in an attempt to learn more about their movement patterns, habitat preferences and daily habits. Even with the highest rates of encounters in the world, our researchers were not seeing them very often and interactions were limited to inshore cleaning stations. If we wanted to know more about this intriguing animal, tagging them with satellite and acoustic tags was the only way to find out more.