Footage showing what is thought to be the first-ever sighting of a live newborn great white shark has just been released – and marine biologists believe the video helps to solve a long-standing marine-biological mystery.
Wildlife film-maker Carlos “The Malibu Artist” Gauna was using his drone to scan Pacific waters near Santa Barbara in California last summer when a “peculiar” shark appeared in the viewfinder – surprising in that it at first appeared to be completely white.
“Where white sharks give birth is one of the holy grails of shark science,” says the film-maker. “No one has ever been able to pinpoint where they are born, nor has anyone seen a newborn baby shark alive.
“While southern California is home to many white shark nurseries, this wasn’t technically in one. It was at a specific location where I’ve made some anecdotal observations over the years that were quickly becoming a trend.”
Experts have long believed that white sharks give birth well out to sea – yet the pup was filmed only about 300m out from the beach.
’Unlike anything I’ve seen before’
Over the previous three years the shark film-maker had been monitoring an aggregation of very large white sharks that would remain visible only for short periods of time. Based on his thousands of hours of observing sharks, he had deduced that at least some of them were pregnant.
“On this particular day, one such large shark was visible,” he says. “It disappeared just beyond the visual depths following some erratic yet unexpected movements. Shortly thereafter this small, completely white-covered white shark appeared. It was unlike anything I’ve seen before.”
Female white sharks bear live pups, which are thought to derive protein from unfertilised eggs while in utero, supplemented by a milky substance secreted by the mother. Gauna was able to film the young shark, which he reckons to have been about 1.5m long, for 18 minutes.
“It’s unmistakable that this is a very young white shark. The problem is, nobody has ever seen one so young before, and this could very well be the youngest ever recorded alive.”
He and University of California Riverside biology doctoral student Phillip Sternes have now written a peer-reviewed research paper about the sighting for the journal Environmental Biology of Fishes.
Sternes thought it likely that the pup was only hours old and one day at the most. While determining its exact age was not possible, several key observations supported the shark being a newborn, say the observers.
The main clue was the rounded shape of the fins, especially the dorsal, which appeared “nearly identical” to those of dead specimens found inside deceased pregnant mothers in the past. The fins remain stubby while constrained within the uterus.
Embryonic layer
When the footage was enlarged and viewed in slow motion, it became clear that the white coating was being shed from the shark’s body as it swam. The study hypothesises that it was shedding its embryonic layer, a white uterine ’milk’, because over the full 18 minutes of footage the shark can be seen to grow darker.
The authors also consider the possibility that the shark was suffering from a skin disorder in their paper, even though no such condition has ever been reported in great whites before.
“Further research is needed to confirm these waters are indeed a great white breeding ground,” says Sternes, “but, if it does, we would want law-makers to step in and protect these waters to help white sharks keep thriving.”
Also on Divernet: California great white sharks boosted, Young great whites chase the heat, Big helpings at the White Shark Cafe, White sharks assemble – in new Atlantic hotspot
