The scent of a whale

Bob and Fargo, both drug-sniffing school dropouts, can smell their floating quarry from a nautical mile away.

Standing like sentinels at the prow of a boat, the dogs stiffen when they catch the scent. Their noses act as compass needles for boat pilots, directing the boats toward the catch. As they get closer, they have to be restrained from jumping into the ocean to retrieve one of the most important clues to a whale's health: its scat.

It's strange science for sure, but examining whale feces is scientists' most effective tool for understanding why there are only about 350 North Atlantic right whales left in the world and what might be done to save the species.

``The dogs' incredible sense of smell is allowing us to study the secrets of an animal as elusive as the right whale," said Rosalind Rolland, a senior whale researcher at the New England Aquarium who began experimenting with the dogs three years ago. ``They can find just a few flecks in the water."

Whales defecate chunks of brown, orange, or neon red dung at the surface before diving. But finding whale scat has frustrated researchers because, while it's incredibly smelly, it sinks in less than an hour. With the dogs' help, Rolland and her collaborators have collected more than four times the amount of whale waste they would normally find on their own -- scat that is helping them understand which parasites, diseases, and red tide toxins might be contributing to the 50-ton beasts' demise.

By examining hormones in the waste, researchers can figure out whether a whale is pregnant or nursing. They can figure out what the whales eat. They can also examine DNA in the sample to link it to a specific whale, because they've built up a library of genetic samples from the tiny population.

Rolland and her collaborators have reported their findings in several scientific journals over the last year and will publish an article on the effectiveness of using the dogs in the Journal of Cetacean Research and Management that is now in press. Scientists say they are in a race against time to figure out why the leviathans are declining and fear that if they don't figure it out soon, the animals could go extinct.

Since 1997, when University of Washington researcher Sam Wasser dreamed up the idea, dogs have been used to sniff out the scat of grizzly bears, cougars, lynx, and other animals as a less invasive research method than tranquilizing them.

Dogs are wired to be smelling machines with a variety of scent receptors and membranes to help detect and distinguish scents. Dogs' sense of smell is likely thousands of times greater than humans', which is why dogs are being drafted for a range of jobs, from sniffing out bombs to bad fish and even cancer.

Unlike fish populations that usually bounce back after fishing pressure eases, the North Atlantic right whale never rebounded after hunting was banned in the 1930s. Scientists know that the whales -- which tend to travel at the ocean surface -- are often struck by ships or get tangled in fishing nets. But they believe that other factors may also be at play, such as pollution that runs off land into the sea, disease, changes in their diet, and, more recently, a lack of genetic diversity. Researchers have scoured ocean swaths from Greenland to Georgia to understand the problem.

But until they began examining whale scat, their methods were insufficient. They could shoot shallow biopsy darts in the whale's skin, but they only got a little information about DNA and blubber. They could study the spray that spurts from their blow holes, but the information it revealed was limited. And while they could perform necropsies, the whales' bodies were often so degraded it was impossible to draw definite conclusions.

Armed with a fine mesh net, Rolland became the first researcher to home in on whale scat to study the whale's biology. She began spending time at their Bay of Fundy feeding grounds in 1999 hoping to catch an oily whiff of their waste and scoop it before it sank. Soon, however, she realized she needed more whale scat than she could get on her own.

And that meant finding a better nose.

That's where Bob and Fargo came in.

Barbara Davenport, of Washington, who helped pioneer the dog scat-sniffing method, rescued Bob, a black and tan mutt then living in a dog pound. Fargo, a purebred Rottweiler, was donated to her by a breeder.

Davenport doesn't train dogs with food, she said, because it could interfere with the dog's nutrition -- or their work, if they aren't hungry. Instead, when the dogs find whale scat, they are rewarded with a few minutes of play with a tennis ball. Fargo and Bob are so obsessive about tennis balls that they would rather play with a ball than eat.

Bob was first trained as a drug-sniffing dog but didn't like jumping up on counters -- a requirement if he was going to go into law enforcement to work in airports or train stations. So Davenport trained him to seek out scat for a carnivore project in Vermont and, later, for whales. Fargo left the drug-sniffing program in part because his body overheats easily -- but he turned out to be perfectly happy in an ocean breeze.

Training for open water searches, however, presented a new set of challenges. Dogs could pick up the scent more easily than on land because there were fewer obstructions to block the scent, but Bob and Fargo wanted to jump in the water and paddle to the smell once they locked in on it.

``Fargo truly believes he can get to the whale waste faster than a boat," said Davenport.

Davenport found a solution by fitting Bob and Fargo with harnesses that Rolland and fellow aquarium researcher Philip Hamilton use to restrain them while on the boat. The dogs, who work separately, indicate where the whale scat is by their body language, which includes wagging their tails and, in Bob's case, barking. Rolland and Hamilton interpret their actions and tell the boat's pilot where to go.

Rolland worked with the dogs with funding from the National Marine Fisheries Service. Now she wants to continue using them to do long-term monitoring of the whales.

But while Fargo will be in the field with her in August and September, Bob won't. Now about 6 years old, he's essentially retired, living with Hamilton in Vermont. And he'd still rather play with a tennis ball than just about anything else.

Beth Daley can be reached by e-mail at bdaley@globe.com