A Brief History of Shark Repellents, In Memory of “Shark Lady” Dr. Eugenie Clark
by Owen James Burke
A fictitious Wayne Industries advertisement for Batman’s shark spray, which would later influence one of the world’s best repellents. Image: Trampt
Before an actual shark repellent was manufactured, the United States Navy’s standard protocol for a sailor adrift during World War I was to flail and splash madly upon the sight of a shark. It was believed that this would scare sharks away. This behavior, of course, is almost certainly the best way to attract the men in grey suits, in large and hungry numbers.
Then with World War II came a wave of other deterrents whose active ingredients were all based around the scent of their dead relatives. Much dispute has gone into whether or not these substances could be deemed effective, but the most brilliant and shocking discovery in shark repellents came from the late Dr. Eugenie Clark, known also as “Shark Lady.” While conducting research in the 1960s, Dr. Clark discovered a milky substance coming from the pores of a tiny flatfish, an ooze which repulsed even hungry sharks.
Shark Lady Dr. Eugenie Clark behind a row of jaws. Photo: John Pendygraft/AP
The United States Navy and Shark Repellents
Above: “Shark Chaser” was the US Navy’s standard issue shark repellent kit from World War II until Vietnam. Photo: SharkDefence
After directing downed pilots and waterborne sailors to flap about like defenseless sardines during the World War I, the US Navy became a little more sensible during the Second World War and began experimenting with semiochemicals — chemicals associated with communication; like attractants, repellents and pheromones. In collaboration with the Woods Hole Oceanographic Institute, the American Museum of Natural History, the Scripps Institute of Oceanography and the University of Gainesville, Florida, the navy developed a shark repellent after concluding that the odor of another dead shark was the best deterrent. They did this by isolating a copper based solution that sharks naturally release when they die — and dissolved it into a black dye, which was supposed to obscure a sailor or downed pilot adrift at sea.
The solution, called “Shark Chaser,” was at first agreed upon as being generally effective, but after a 1971 report by the Office of Naval Research concluded that “Careful controlled studies on the components of Shark Chaser…have shown this product to be of little or no value in controlling aggressive shark behavior,” the Navy eventually ditched it.
The semiochemical shark repellent was developed by British defense and security company BCB in 1967, and would go on to replace Shark Chaser. It’s still in production, and it’s available on Amazon.
Next came a shark repellent designed by British defense and security company BCB who also marketed the world’s first ever life raft survival kit. Their product is NATO-approved for life rafts and airborne survival kits, and is still in use to this day by many of the world’s navies.
Meanwhile, the Batman series had a laugh at the US Navy’s strange concept of developing a shark repellent:
For anyone who ever watched the 1966 Batman film, it’s hard to consider shark repellent in an aerosol can without conjuring up an image of Adam West (as Batman) dangling from a helicopter ladder while a fake as hell shark hangs from his calf. Batman calls up to Robin for shark repellent, but it takes his trusty sidekick a moment to sort through the rack of various sea monster deterrents, which also contains whale shark, manta ray and barracuda repellents. Laugh all you like, but story has it that the film inspired this repellent that is derived from putrified shark carcasses comes in an almost identical aerosol can some forty years later.
Dr. Eugenie Clark and a Strange Fish
While conducting research in the Red Sea, Dr. Eugenie Clark discovered the first natural shark repellent known to man in the Moses sole (Pardachirus marmoratus). The small flatfish (above) releases an intoxicating milky substance out of its pores to deter sharks and other predators. (Photo: John E. Randall/Encyclopedia of Life)
Two years before the Batman movie, Dr. Eugenie Clark, an ichthyologist and marine conservationist who would famously come to be known as “Shark Lady” was on a research expedition in the Red Sea when she became the first person to discover a natural shark repellent. While studying a flatfish called the Moses sole, she noticed a milky secretion emanating from its pores when the fish sensed a nearby threat. Ichthyologists have known about this substance found in flatfishes since the 1800s, but it wasn’t until around 1971 when Dr. Clark, researching with the University of Maryland, described the alarming effect it had on sharks. The substance stopped all predatory fish, including sharks, dead in their tracks. A shark in full pursuit would suddenly turn and storm off in a fit without its catch.
A controlled experiment in the laboratory further exposed the effectiveness of this pungent defense mechanism. A shark was put into a test tank with one such flatfish. It confidently approached the sole, mouth agape, but just as it was about to sink its teeth into an easy meal the shark retreated and turned belly up at the bottom of the tank, paralyzed, and moving only its jaws. The effect lasted from from a few seconds to a few minutes.
This bizarre substance came to be called pardaxin. It’s a peptide that attacks the gills and paralyzes the mouth of anything that comes too close to the hypersensitive flatfish.
These findings put dollar signs in the eyes of the sunscreen company Coppertone, who logically sought to incorporate pardaxin into their sunscreen. Unfortunately, explained Dr. Clark at a press conference, paradaxin’s efficiency varied by temperature and would only remain effective for 24 hours at room temperature and if the chemical is frozen, its effectiveness plummets. Clark was also highly doubtful whether or not the substance could be deployed in time, given the fact that most folks who are attacked by sharks have little or no warning, so she refused to endorse it.
Above: “A2,” the shark repellent agent inspired by Batman, is tested on the appetite of a lemon shark by SharkDefense Technologies. Photo: Michael Hermann/AP
In 2004 in the Bahamas, world-renowned shark scientists Dr.’s Eric Stroud and Patrick Rice tested a repellent which has at least been proven to deter smaller reef-dwelling sharks. One Amazon reviewer, a spearfisherman, was able to keep a pair of bull sharks at bay in the Gulf of Mexico while surrounded by blood, spraying a couple of mini canisters of the product, pictured in an aerosol can below.
Above: A Shark repellent derived from putrified shark carcasses developed in 2004 by SharkDefense Technologies. Photo: UPC Barcodes
A similar compound seemed to work for Philippe Cousteau in the below video from the BBC.
In 2011, BCB defense systems updated their original semiochemical shark repellent by incorporating a sea marker dye for use in man overboard situations. The dye is visible for over a mile and lasts for about 40 minutes, but there has been no evidence — none published at least — that it is any better equipped to put off sharks, and one might wonder whether the curious green dye may have the potential to attract the attention of an unwanted companion while adrift at sea.
Shark Repellents and Surfing
The surfing industry has devoted some research and design into repelling sharks, too, but mostly focusing on sharks’ sight and electromagnetic fields (it’d be kind of hard to surf with — and engage — an aerosol can in your wetsuit). So far, they’ve come up with everything from electromagnetic leashes — which are supposed to overwhelm the shark’s electroreceptors (called ampullae of Lorenzini) — to aqua-camouflage and zebra-striped wetsuits and surfboards made by an Australian company called Shark Attack Mitigations Systems (SAM). The aqua-camouflage is designed to obscure you in the water, while the zebra stripes are meant to imitate the patterns of sea snakes and cleaner fish, which sharks don’t tend to eat. The technology (at least for the zebra-striped suit) is tested and proven as best as it can be (see the video below), but one can’t be too sure of how it might work in the surf, where a shark relies upon its sense of sight least.
And, if patterns are a variable in whether or not a shark might take a curious taste, black and white has the potential to be an attractant, argues the director of the Florida Program for Shark Research, Dr. George Burgess: “That striped suit that is supposed to look like a lionfish is about as nice a thing as you can do to attract a shark, because of the contrast between dark and light.”
Sharkbanz is a one-size-fits-all anklet/bracelet that disturbs sharks’ electromagnetic receptors. Photo: Sharkbanz
One of the most recent developments has been Sharkbanz, an anklet/bracelet produced by a father and son duo out of Charleston, South Carolina. It’s lightweight, unobtrusive, doesn’t require batteries or charging, and, unlike the $800 shark repelling leash, is an affordable $60. If I were to put my money into any shark repellent gear, especially if I were a parent with young kids running around in murky, shark-laden waters, it would be the Sharkbanz.
Some of these devices have proven their efficacy and deserve their merit, but for better or worse, I’ve got enough gear on me in the water on any given outing. I’ll keep taking my chances.
Protecting Sharks, Not People
Today, in light of recent conservation efforts being made on behalf of sharks, much research is being dedicated to producing repellents not to protect humans from sharks, but to protect sharks from becoming bycatch aboard commercial fishing vessels where they are not the intended catch. Surfactants (compounds that lower surface tension between liquids such as dispersants and emulsifiers) are currently being tested for this purpose, including sodium lauryl sulfate, a compound made from coconut and palm oils found in shampoo. Still yet, scientists have not found a way to produce a high enough concentration of the solution to produce a cloud potent enough to deter sharks from fishing gear.
Photo: SportDiver/Courtesy of Nina Leen/Mote Marine Laborator
It would be a hard argument to make to say that shark repellent research (for the sake of both sharks and humans) would be where it is today without Dr. Eugenie Clark’s early discovery of the Moses sole’s defense mechanism today, yet it would be impossible to make any claims that sharks — and people — aren’t better off for having been graced with her presence on this earth.
Rest in Peace, Dr. Clark. — OJB
A List of Available Shark Repellents:
Sharkbanz comes in two colors, though I don’t think that matters much. Sharks have a scientifically proven aversion to the disruption of their electromagnetic sensors, and with no battery needed, this is probably your easiest method of prevention, if you’re looking for one.
If you’re really having a hard time getting into the water for fear of sharks but can’t do without swimming, surfing or diving, you may want to look into this electromagnetic leash which, at about $800, is an expense I’ll forego, but never enough can be said for peace of mind. There are only a couple of reviews on Amazon, and one complaint concerning the battery life. It’s supposed to last 7 hours, but the Amazon customer only managed 3 hours out of it. Cold water may be at play, but 3 hours is still an extraordinarily long dive.
There’s no chance you’ll be taking this stuff with you surfing, but a spearfisherman in the Gulf of Mexico put it to the test against two “aggressive” bull sharks and came out unscathed. Probably not a bad buy if you’re going to be hunting in sharky seas.
This is the original stuff the US Navy used, along with many other navies around the world. It’s small and affordable enough that it’s probably not the worst thing to have in your life vest or dive kit.
Lady with a Spear (1953)
The Lady and the Sharks (1969)