On land, time wouldn’t be limited like it is by a diver’s air supply. Sampling the shark underwater afforded no such luxury. It was more of a crude sampling effort than a necropsy. However, for Wimmer, any information is invaluable. “Whether it is something natural or human-caused, we need to get a handle on what threats and causes of deaths, what causes of illness and injury these animals are experiencing, and we really don’t have any of that information for white sharks,” she says.
Forty minutes into the dive, it was almost time to return to the wharf before the divers’ air ran low. One last gruesome but necessary task involved removing the head with a dive knife. Enclosed in the skull in the cold water, there was a chance the brain could be useful, as this piece of information might help provide clues to the shark’s demise.
Encephalitis (inflammation of the brain), possibly caused by bacteria, has been suspected as a possible cause in the Lamniform family of sharks, to which great whites belong. “What we have been finding in our great white shark necropsies is that some of the ones we’ve been seeing also have some brain inflammation,” says Wimmer. She explains that MARS and the scientists they work with have been trying to find answers, “they’re still tracking down what may be the cause of it if they think it actually has anything to do with cause of death,” she continues.
The divers played a small but vital role in what is a long, complex investigation involving many people and, for divers like Vanderkaden, that is not lost on her. “It was a gratifying moment to get to leverage my role as a recreational scuba diver and get to contribute positively towards marine conservation in this,” she says.
It will take many more months for the samples to be processed by scientists and perhaps much longer to find answers. Yet, with every piece of new information, MARS and the scientists that depend on their work add another piece to the complex puzzle, that is, the mysterious lives of great white sharks in Atlantic Canada and what might be killing them.