Company strives to develop shark repellent

Protecting, not killing them, is focus, founder says...

Imagine a lifeguard shooting a repellent bomb out of a potato gun into the surf to scare away sharks. Or a sunscreen swimmers could apply that makes sharks swim away from them. Or — for commercial fishermen — longline baits spread along 30 miles that no shark would bite.

It might sound like something cooked up by Dave Barry or even Buck Rogers. But developing a universal shark repellent is the goal of a small New Jersey company called Shark Defense (sharkdefense.com) working with University of Miami professor Samuel "Doc" Gruber at his Bimini Biological Field Station.

Said company founder Eric Stroud: "It's not about killing sharks. It's about making them go away."

Added Gruber, a lifelong shark conservationist and researcher: "I'm helping develop this to protect sharks — not humans. It'll save 40,000 sharks a night, which is so much more important."

Ecosystem in turmoil
Worldwide, 61 people were attacked by sharks last year and seven of those were fatal. But humans are responsible for the deaths of millions of sharks each year by catching them in longlines and nets or cutting off their fins. Gruber and other scientists say this is a dangerous trend because the annihilation of sharks upsets the ecology of the oceans.

Efforts to develop a shark repellent are nothing new. For centuries, fishermen have known that leaving a dead shark's rotting carcass in the water frightens other sharks. During World War II, the U.S. Navy attempted to parlay this finding into a repellent called "Shark Chaser" to protect pilots shot down in the ocean. Theorizing that ammonium acetate found in rotting shark tissue was the key ingredient, the Navy put it into balls of soluble wax that emitted a black dye, like an octopus. The late cooking diva Julia Child was among those who worked on the product when she served in the OSS.

The stuff didn't work. Sometimes the black dye succeeded in repelling sharks; other times, pilots got bitten. Nevertheless, Shark Chaser was used all the way into the Vietnam War.

In the post-Vietnam Cold War of the 1970s, another shark-related problem beleaguered the Navy: The animals were biting expensive hydrophone arrays towed by U.S. submarines to listen for enemy activity. Gruber got a grant to try to solve the problem and, in the 1980s, came up with a formula using a common ingredient in household detergent, sodium lauryl sulfate, that mimicked a shark-repelling protein found in Moses sole, a fish common in the Red Sea. But it was impractical for the Navy to use, and eventually the research was abandoned.

Then in the late 1990s, along came Stroud — a young chemist in Oak Ridge, N.J. — and his partner, Michael Herrmann, an engineer.

Bottling the rot
Unlike their predecessors, Stroud — now 31 — and Herrmann, 37, vowed to extract the exact chemical compound from rotten sharks that would guarantee driving away other sharks. And they said they would develop practical ways to deliver it, such as a lotion applied to the skin; a mortar shell fired by lifeguards; or a sponge embedded in a longline bait.

This research has taken years and is not complete, but Stroud believes a breakthrough is imminent. Meanwhile, he and Herrmann are testing various formulas and delivery systems on the local shark population near Bimini.

Stroud and Herrmann wanted to see how a bug-bomb-like grenade filled with one of their repellent formulas would affect a school of Caribbean reef sharks that Gruber chummed up near Triangle Rock.

First they launched sort of a placebo, dropping a canister containing only alcohol into the water. Four sharks up to eight feet long attacked the canister. A second canister, this one emitting repellent, was deployed midway down in the 20-foot-deep water. Initially, the sharks were frightened off, but they soon returned.

Then things got kind of weird. Stroud donned a backpack with a gun that looked like the one used in Ghostbusters. He jumped into the water, pulled the trigger and scared every shark away.

The scientists said the experiment was "inconclusive" because the cloud of noisy bubbles easily could have repelled the sharks, rather than the formula itself.

Their longline trials were more successful. Deploying five sets of 15 baited hooks in a shallow lagoon, the researchers treated 15 of the baits with repellent and left the rest untreated. They checked every four hours around the clock for 24 hours. The longlines with repellent produced no shark catches; the other lines yielded four blacktips, four nurse sharks and one tiger shark. Sharks were released.

The work took another strange turn when Stroud "hypnotized" some sharks and discharged various concentrations of repellent formulas near their snouts to see the reaction.

Of course, sharks cannot be hypnotized. But the scientists were able to put the animals — some of them eight feet long and thrashing — into a state of "tonic immobility" by turning them upside down.

A small lemon shark had a particularly violent reaction to one of the formulas. Lying immobile in researcher Mark Corcoran's grasp, the shark suddenly snapped its jaws open and went into a twitching seizure.

Alarmed, Corcoran held it upright and walked it slowly through the shallows for nearly an hour to revive it.

Stroud watched, worried.

"Testing over 500 compounds, we've only come close to injuring a shark twice," he said. "We've never killed a shark. We don't want to."

Source: www.chron.com