Growing use of pingers worldwide

expert on pingers. "You could put your head right next to one of our pingers and it wouldn't hurt you."

The pulses are dispatched every four seconds. For undersea animals, who use sound to help them "see," the pings illuminate a net like a street lamp.

Whales or dolphins apparently blunder into nets when they are swimming along, perhaps in a sleepy daze. Hearing the unusual ping, the animals might turn on their echo-locators - their sonar - and then they can sense the net.

"We hope they are alerting devices, but we don't know exactly what it is the animal is responding to," Kraus said. "Is it like a yellow line on the highway that alerts you that you're running off the road, or is it actually scaring you, making you run away from it?"

At San Diego's Sea World, new research on dolphins shows that the pingers may not be as benign as everyone has hoped.

Although the animals in the experiments are not harmed, they do seem to be disturbed by the noise. When nets with pingers are put in Sea World's small tanks, dolphins do not merely avoid them, they hurriedly swim away.

"They are staying away because they hear this nasty sound. Scared might be too strong of a term. Annoyed may be the best way to put it," said Ann Bowles, a senior biologist at the Hubbs Sea World Research Institute, the nonprofit research arm of the marine animal park.

In the vast ocean, however, instead of a small tank, the disturbance to cetaceans may be minor because there is plenty of room to escape the sound, Bowles said.

Despite the questions that remain, Bowles and many cetacean experts endorse pingers because they clearly save animals' lives. She warns, though, that "they need to be deployed very judiciously" so that dolphins, porpoises and whales do not encounter them often.

Reactions of Other Species

The National Marine Fisheries Service recently mounted projects to monitor the behavior of porpoises around the pings and check for any long-term impacts on the entire marine ecosystem, from zooplankton to squid.

One unfortunate side effect is that seals and sea lions might be getting entangled more often in nets with pingers, said Dave Potter, a research oceanographer with the federal agency. The pings could sound like dinner bells to the animals, letting them know where to find fast food caught in a net. But seals and sea lions are extremely abundant animals, unlike the endangered whales and harbor porpoises the pingers protect.

Pingers were developed only after fishermen's numerous attempts at other fixes failed. Fearing that deaths of harbor porpoises might cause federal officials to shut down the entire Gulf of Maine fishery, they tried colorful mesh and reflector lights, and tying their sink nets down instead of hanging them up straight. Nothing seemed to work.

Loud acoustical alarms had been tried back in the 1970s at catfish and salmon farms to scare off seals. They failed miserably.

But in the early 1990s, Jon Lien, a marine mammal behaviorist at Memorial University in Newfoundland, experimented with a new acoustical concept to keep humpback whales out of cod traps: low-volume pings instead of loud alarms, with the idea to warn the whales, not scare them.

Lien enthusiastically hooked up with New England fishermen to try alarms on gill nets. They crafted some pingers, trying various versions, and after a year of effort, they were convinced they had found ones that worked. Still, no one but the fishermen believed it.

Convincing the National Marine Fisheries Service, which regulates fisheries, required a full-scale, precisely controlled, peer-reviewed scientific test.

The results of such a study, which Kraus conducted in 1994, were stunning.

During a two-month period, two porpoises were caught in 421 nets equipped with active pingers, compared with 25 in 423 nets set up with dummy pingers.
It was more than a tenfold difference - a 95% reduction in porpoise deaths.
"Then," Barnaby said, "the whole world started paying attention."

Today's pingers are no longer handmade - sold worldwide instead by a company that makes aircraft transponders.

Still, in part because of disagreements among fishermen, it wasn't until December, after being sued by conservationists, that the National Marine Fisheries Service required pingers for the Gulf of Maine's estimated 250 gill net vessels.

Ironically, the ground fish industry in New England may not survive anyway. Cod and other species are near collapse.

Off California, commercial fishing of swordfish and thresher shark is a healthy, $30-million industry. But every year, several hundred whales and dolphins are killed by the drift nets that catch the prized fish.

Even though only a few sperm, humpback and pilot whales die each year, the fishermen's "take" exceeds the limit that biologists say endangers the existence of the whales.

Facing imminent restrictions on fishing, a team assembled by the federal government two years ago recommended an experiment on the West Coast with the pingers invented back East.

The California results were also dramatic: a 65% reduction in deaths of whales and dolphins.

"It's hugely successful here," said Irma Lagomarsino, a fishery biologist with the National Marine Fisheries Service in Long Beach. "It's exactly where we want it to be. But we need to keep looking at it to make sure it works for all the species of concern."

West, who has spent 50 years as a commercial fisherman sailing out of San Pedro, called the pingers a good investment in sustainable fishing.

West hasn't netted a whale or dolphin since he spent $1,700 outfitting his mile-long net with 41 of the alarms. And he discovered they save him money - fewer entanglements means less damage to his $25,000 net and fewer swordfish escape.