The ‘Ping’ Heard ‘Round the World

Killing a porpoise can haunt a man--even a fisherman accustomed to life and death at sea.

Erik Anderson, who has fished New England’s waters for 30 years, would haul up his gill net and occasionally discover a harbor porpoise, entangled and dying, trapped in the mesh along with his harvest of cod and flounder.

Every time it happened, six or seven times a season, Anderson worried. Each death of a porpoise heralded deep trouble for fishermen.

Up to 2,000 of the animals were drowning in gill nets in the Gulf of Maine each year--enough to eventually wipe out the species. And if nothing was done soon to stop it, the already struggling fishery would be shut down by federal authorities.

To avoid that fate, fishermen--first in New England and now in harbors around the world--decided to take matters into their own hands.

Following a hunch about acoustics from a Canadian whale behaviorist a few years ago, Anderson and some of his colleagues started experimenting with their nets.

At RadioShack, they purchased a batch of the devices that sound a beep on school buses when they back up. They tied the bulky boxes onto their gill nets, and set them into the Gulf of Maine. It was decidedly low-tech, and risky at that. But amazingly, porpoises heard the low-frequency alarms and avoided swimming into the nets. Rarely were they ensnared.

Now, word is spreading around the globe, fisherman to fisherman. Ping, ping, ping can be heard in ocean waters from South Africa to the Irish Sea.

Called “pingers,” net alarms are considered so successful in protecting marine mammals that a federal order recently mandated them on drift nets off California and Oregon and sink nets in New England.

Deaths of whales and dolphins have dropped by two-thirds on the West Coast--with 90 common dolphins dying in 1997, compared with a past average of 271 annually. Killings of some whale species, including sperm, humpback, beaked and killer whales, dropped to zero. On the East Coast, porpoise deaths in the Gulf of Maine have declined by more than 90%.

“You just can’t be a fisherman these days without being attentive to these other [conservation] issues,” said Anderson, who spent $3,000 equipping the gill nets on his 40-foot vessel with pingers. “Ultimately the fishing industry has the solutions to these problems right at their fingertips.”

Early Successes but Questions Remain

At first skeptical of the fishermen’s idea, many marine scientists are now confident that pingers save the lives of many cetaceans. Yet they don’t fully understand why they work, or what impact the noise might have on ocean creatures. Cautioning that pingers are not a cure-all, they worry that their use is spreading faster than the science.

Conservation groups endorse pingers, but they also wonder if the undersea cacophony could disrupt nature in ways we don’t yet understand, or if cetaceans could eventually get so acclimated to the pings that they start ignoring them.

“Right now we know that they work, but we have a lot more questions than we do answers,” said Nina Young, a research scientist at the Center for Marine Conservation. “Whenever you have a new technology, you have to enter into it slowly and determine the effects.”

Fishery managers believe that a few low-decibel pings in the ocean, usually inaudible 300 meters away, have to be better than killing porpoises in Maine or sperm whales in California.

“I’m a firm believer,” said Tony West of San Pedro, who is one of 90 California fishermen who must use pingers when deploying drift nets for swordfish and thresher shark.

“We’re in the infancy stage, so there’s a lot of improvement needed from a practical standpoint from the fisherman’s point of view,” he said. “But I’m ecstatic about the success we’ve had. . . . And they haven’t hurt us one bit in terms of catch.”

Pingers may offer the last, best hope for troubled fisheries around the world.

Gill nets--which can stretch a mile across the sea--are the world’s most common commercial fishing gear. But the mesh often unintentionally ensnares marine mammals, perhaps hundreds of thousands a year globally.

In the United States, the Marine Mammal Protection Act forbids fishermen from killing mammals in numbers considered unsustainable for a population. In some cases, government officials believed that the only way to meet those rules would be to shut down a fishery. But the invention of pingers has averted such draconian steps.

“Anyone involved with this issue . . . knows there wouldn’t be a gill net fishery in New England if pingers didn’t come along,” said Roland Barnaby, a fishery education specialist at the University of New Hampshire’s Sea Grant program.

The pings may be the undersea version of highway reflectors, warning marine mammals to slow down and pay attention. Scientists hope that the noise isn’t loud enough to scare them, but instead warns them that an obstacle lies ahead.

The ocean is a noisy place, and the devices are programmed to broadcast the pings at a level as close to background as possible while still being loud enough for an animal to hear at least 100 meters away--in time to change course. The signals are sent at 15 to 30 decibels over ocean noise, or 132 decibels (equivalent to 192 decibels above ground, the level of a light conversation).

“We wanted the minimal amount that would still work but wouldn’t make the ocean sound like a lot of racket,” said Scott Kraus, a scientist with the New England Aquarium who is a leading 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.

Exploring Alternatives

Still, for California drift netters, who often fish 200 miles offshore, installing pingers at sea can be perilous and time-consuming. The hand-sized orange canisters are attached to a line on the net, one pinger for every 300 feet of net.

“It takes about an hour to put them on and another hour to take them off,” West said, “and it can be Victory at Sea out there. Sometimes it’s just hellacious weather.”

More practical solutions, however, are probably near. With larger pingers, fishermen might have to install only two or three per net.

American fishermen are now seeking government help in bringing pingers to fishing boats in Mexico, to save endangered porpoises in the Gulf of California known as vaquita.

Despite the bicoastal success stories, fishermen and government regulators must be cautious in how and where pingers are deployed. They probably won’t work for every fishery or for every species of marine mammal, so each area must be studied first.

“All marine mammals do not hear the same,” said oceanographer Potter. “They are as diverse as mammals on land. Comparing a right whale to a porpoise is like comparing a cow to a dog.”

Cliff Goudy, director of the Center for Fisheries Engineering at the Massachusetts Institute of Technology, remains skeptical about how well pingers will work in some fisheries.

One technique that may work better, he said, is to warn fishermen about the marine animals--instead of the other way around. Goudy is testing acoustics to locate right whales during spring migration. Then, like flight control warnings to airplane pilots, fishermen could be warned to stay out of their path.

Because no fishing gear is perfectly selective, diners must accept the deaths of dolphins, whales and seals if they want to enjoy a meal of fresh fish, both fishermen and scientists say.

“We’ve never said the pinger is the panacea for the by-catch issue. It’s just another tool,” Kraus said. “There will always be animals that make mistakes. We will never eliminate by-catch altogether unless we eliminate fishing.”

(BEGIN TEXT OF INFOBOX / INFOGRAPHIC)

Underwater Alarm

Drift nets off California and Oregon must be equipped with acoustic alarms called pingers to warn dolphins and whales. Here is a look at net deaths of selected species on the west coast, before and after pingers were introduced in 1997. Overall, cetacean deaths dropped 65%.

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1991-1995 1997 Common dolphin 271 90 Northern right whale dolphin 47 25 Risso’s dolphin 37 8 Cuvier’s beaked whale 28 0 Dall’s porpoise 22 17 Pacific white-sided dolphin 22 11 Pilot whale 13 6 Mesoplodont beaked whale 6.6 0 Sperm whale 4.5 0 Humpback whale 1.2 0

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*annual average

Hand-sized orange canisters are attached to a line on the net and are spaced every 300 feet.

Signals are 132 decibels (equal to 192 decibels above ground), which is 15-30 decibels over ocean noise, or the level of normal conversation.

Pinger alarms are programmed to transmit sound just loud enough for animal to hear it from about 300 feet away.