Gauging the Threat – A Study of the Number of White Sharks in Gansbaai

South Africa was the first country in the world to declare the great white shark a protected species, when they did so in 1991. At the time the great white population of Gansbaai was estimated at roughly 2,000, but recent statistics released from an ongoing 5 year study of Gansbaai’s white shark population has those estimates down to 1008 at best.

That’s 50% down on the stat which the decision to declare them a protected species was based upon, and that’s alarming for anyone who has an interest in keeping our oceans from jumping out of synch due to a vital piece of the eco-system becoming extinct.

It’s also why Zag scribe Anton Louw was so keen to go and listen to findings from the latest research that were presented at the 2 Oceans Aquarium this week.

*********

Gauging the Threat – A Study of the Number of White Sharks in Gansbaai
by: Anton Louw

I’m a surfer who loves sharks. I love the way they always flash a jagged grimace as a reminder of who is master of the domain. I love the way they glide calmly through the water, before dropping their pectoral fins and forming a thruster when they strike. I love the way every time I enter the water I can return to a wilderness like our ancestors knew.

Yet, I’m also terrified. I dread that my yet to be born children and their generation may never know them as we do. I would be mortified to sit a grandchild on my lap and have him ask me what is was like surfing when there used to be sharks. I try not to imagine my fumbling response to that question.

I’m fortunate that I’m not alone in this fear. Researchers, conservationists and activists have been fighting for this for some time. It’s also inspiring to see surfers and other ocean users, and even victims, joining the campaign in their own ways. But, there is still much to learn before we actually know how dire the situation is.

Researcher Michelle Wcisel leans in for a closer inspection.

The cage diving industry is maligned for the perception that it is habituating sharks to a human presence and this leading to more attacks. It’s a tired conversation not worth rehashing. I’m still waiting to hear a coherent, grounded argument against it which isn’t based on inappropriate metaphors.

Although the industry is far from perfect or entirely benign, both detractors and supporters have the sharks’ interest at heart, although I suspect many detractors use the sharks’ wellbeing as a proxy argument for their own fears. Even if you question their method of funding, the research being done by operator Marine Dynamics can only stand to benefit shark conservation.

When you hear director Wilfred Chivell’s passion when he talks about the plight of sharks, and have seen the lengths he’s gone to host research and further improve marine conservation, you can’t doubt his motives. And his surfing son’s local area has, in all likelihood, the most dense population of White Sharks in the world.

Here’s a lineup featuring just a few of the over 500 great white’s already identified by the Marine Dynamics team.

Marine Dynamics hosted an evening at 2 Oceans Aquarium presenting their latest research based on fin identification to assess the local population of Gansbaai. Using open source software called DARWIN they managed to record 532 individuals over 5 years, and from this estimate the superpopulation to be between 800 and 1000. While this might sound good (or bad, depending on your perspective), it’s around half of what previous estimates have been, and it appears that they haven’t seen a significant recovery since protection in 1991. Although they’re protected here and in Namibia, 30 to 40 still die annually in Natal’s shark nets, and others are being fished out in Mozambique. As tagging studies have shown that Gansbaai’s sharks travel along this coast frequently, it does not bode well for this slow growing, late maturing species.

Ultimately, the research aims to affect policy. But, although decision makers might acknowledge research, they respond much better to public sentiment. As Aquarium director, Dr. Pat Garret, puts it, the species won’t be saved “by the science of sharks, but by the science of people.” Michelle Wcisel, one of the co-authors of the paper, knows this. So instead of just releasing the academic paper in its dry scientific language, and measuring success by how many subsequent papers cite it, they’ve also released this infographic for the general public. Although they acknowledge that education is a slow process, there are encouraging signs. They’re already pleased that local media are less sensationalist than those abroad. Wilfred has also successfully lobbied the Afrikaans media into changing the name away from the Wit Dood Haai to remove the hyped up connotations. (Not to bash Afrikaans; I’ve got an old reference book that labels it Maneater.) They also believe that every tourist who takes a trip leaves more educated and empathetic towards sharks – although some operators certainly don’t place as much emphasis on this as others.

Open Source software called ‘Darwin’ helped the team identify the individual sharks.

From here, the aim is to engage the broader public. One method is citizen science where interested citizens are able to help generating data through submitting sightings or photos. This method would have shocked scientists in the past, but is now being seen as not only a tool to gather data, but also a great way of engaging the people to whom the findings ultimately matter.

Although a picture is emerging, there is still much we have to learn about White Sharks and their future is far from certain. Let’s imagine two scenarios – In the first one, attacks continue at a stable or slightly increased rate owing to more of us in the water. (Think about that the next time you hear how uncrowded it used to be.) An attack might happen at your local beach, or to someone you know, and will be deeply unsettling when it does. But, weigh this against the alternative: shark attack numbers start dwindling until one day the last one happens. Which scenario would put you more at peace?

For the original academic paper, click here.

***

And as much as I like sharks, I’m not an expert, just a fan. If you have any questions, please put them below and I’ll do my best to answer them. Accusations and threats are also welcome.