Does Shark Diving Harm Sharks?

In this edition of Ask a Marine Biologist, Dr. David Shiffman answers a question about swimming with sharks.

Are “dive with the sharks” trips ethically OK, or does this harm the animals? Are there things we should look out for to figure out if a given company is good or problematic?

—Jon D., Michigan

Answer: Lots of “swim with the sharks” dive businesses are run by ethical operators who care about the safety of humans and sharks, but some are run by macho cowboy idiots who are unsafe and cause harm to sharks. The good news is that it’s usually not that hard to tell the difference! First, let’s go over the types of harm that can possibly be caused by careless human-wildlife interactions.

It’s relatively rare for something like this to result in the actual death of a shark, but it happens. Last year, a great white shark died after its head became trapped between the bars of a cage off Guadalupe Island, Mexico. Details of this incident are sketchy and conflicting, but from what I’ve been able to gather from reading news reports, speaking to expert colleagues in the region, and following along with the back-and-forth as best I can from thousands of miles away, what happened in this case was that a shark cage diving operator did not follow proper cage design regulations—if it had then it would have been impossible for the shark to get stuck in the cage and eventually die, according to the Mexican government. This incident reminds me of a very stupid Shark Week episode where they built a giant shark cage for Shaq, and the bars were so far apart that a shark actually got all the way inside the cage with him.

It's much more common for careless shark diving practices to disrupt the natural behavior of the animals than to immediately kill them. This is sometimes harder to detect. You can’t just say, “The shark would have left if it wasn’t happy.” This kind of sublethal harm can result in injury, disease or physiological stress, all of which can affect a shark’s long-term ability to survive, reproduce and play an important ecological role. This goes for other species too. For example, at the long-term wildlife tourism spot Stingray City, tons of food from tourists has resulted in a huge and concentrated population of stingrays, animals that are usually solitary or found in much smaller groups.

As a result, stingrays there are more likely to be injured, infected with disease or parasites, and generally be in worse condition than undisturbed stingrays. We also don’t really know what taking all of the stingrays out of their natural food web by getting them to rely on tourist-provided food does to the rest of the ecosystem, but it’s probably not great. Similar concerns have been raised at Hawaii manta night dives and Philippines dive-with-whale-sharks sites, as well as lots of other similar places. I should note that feeding or chumming is not necessarily indicative of a problem (as argued by my Ph.D. adviser, an occasional light snack is unlikely to cause a major behavioral disruption), but feeding a lot is likely to be a problem.

One huge red flag about a problematic shark diving operation is if people associated with the company grab or ride the sharks they attract or otherwise encounter. Let me be clear: This is not education, this is not conservation, this is not saving sharks—this is wildlife harassment. Sometimes wildlife harassment takes the form of flipping sharks over, triggering their tonic immobility response (many sharks basically fall asleep when they’re upside down), because some people think that it’s funny to watch a shark fall to the seafloor on its back. Tonic immobility causes physiological harm to sharks. It is sometimes done by actual trained and credentialed scientific or veterinary experts with the goal of quickly and safely taking scientific samples from a shark, but if it’s done for the purpose of watching a shark fall to the seafloor or getting a cool picture of a person holding a shark, it’s bad. Sometimes this harassment literally takes the form of riding sharks, which is sometimes justified as “raising awareness of shark conservation.” To reiterate, it is no such thing.

As for other red flags to be aware of and other signs of a good operator, the rules are pretty similar to my guide to identifying eco-friendly dive operators in general. Does the operator take care to educate their customers about actual verifiable facts related to shark science and conservation, or do they engage in meaningless platitudes and greenwashing while repeating nonsense that doesn’t actual help the ocean in any way?

So in summary, can you dive with sharks without causing harm to sharks? Absolutely. And doing this can be an incredible, transformative experience that creates a shark fan for life! But some common shark diving practices are problematic and risk harming humans and sharks alike, so be on the lookout before you book your trip.

Ask a Marine Biologist is a biweekly column where Dr. David Shiffman answers your questions about the underwater world. Topics are chosen from reader-submitted queries as well as data from common internet searches. If you have a question you’d like answered in a future Ask a Marine Biologist column, or if you have a question about the answer given in this column, email Shiffman at WhySharksMatter@gmail.com with subject line “Ask a marine biologist.”

Dr. David Shiffman is a marine conservation biologist specializing in the ecology and conservation of sharks. An award-winning public science educator, David has spoken to thousands of people around the world about marine biology and conservation and has bylines with the Washington Post, Scientific American, New Scientist, Gizmodo and more. Follow him on Twitter, Facebook and Instagram, where he’s always happy to answer any questions about sharks.

The views expressed in this article are those of David Shiffman, and not necessarily the views of Sport Diver or Scuba Diving magazines.