Whale advocates concerned about sonar in Strait

Orca advocate Jeanne Hyde reports on her blog, whale-of-a-porpoise.blogspot.com, that loud pings believed to be from a ship's sonar were recorded over an eight-hour period in Haro Strait Tuesday and today.The pings were recorded over hydrophones stationed at Lime Kiln State Park and about three miles north of Lime Kiln. Hyde reported she was told by the U.S. Coast Guard that the sounds came from a U.S. Navy submarine. "Unfortunately for all those marine mammals nearby and their inner ears it seems that a vessel came through using its sonar several times as it passed by in the inland waters," Hyde reported. "I'm assuming it was the Navy as there was this electronic sounding voice ... sounded like it was counting down ... I could hear the number 9 and the number 6 clearly within the 'counting' or whatever it was doing ... then there would be no more electronic sounding voice ... then it would start again ... it was difficult to tell if it was repeating the same thing over and over or not ... but several times I heard the 9 and the 6 clearly ... then ... then ... SONAR."Hyde said the sonar "actually hurt my ears as I heard it over my computer speaker ... I can't imagine what it was like to any marine mammal that may have been near."You can listen to three of the pings here: 7:10 P.M. , 9:50 P.M. , 12:38 A.M.."The first sonar that I heard was on the Lime Kiln (hydrophones) — loud," she reported. "(T)he next sonar that I heard was softer and more like a drawn out ping again ... but then I heard from someone else that it was louder on Orca Sound (hydrophones) which are a few miles to the north ... so I switched to (Orca Sound hydrophones) and the next sonar was loud ... then the next time it got softer ... so I thought they were going north through Haro ... but then ... really loud sonar with a long long lasting ping."Hyde reported "three loud, high-pitched beeps" at 12:24 a.m., followed by a series of countdowns and other pings. She reported "hurt my ear" kind of pings at 12:43, 12:48, 12:59, 1:11, 1:31, 1:41, 1:57, and 2:01 a.m. Sonar pings continued until about 3:12 a.m., she reported.Whale advocates and scientists believe sonar pings can be harmful to the endangered killer whale population and other marine mammals in the inland waters. On May 5, 2003, the Center for Whale Research observed porpoises, killer whales and a minke whale seemingly attempting to flee from sonar pings from the USS Shoup (DDG-86); the pings were measured at 230+dB 3kHz. Two dead porpoises were found immediately following the sonar incident on shores adjacent to the destroyer's path, and a total of at least 10 porpoises died in the approximate time-frame of the incident. At a necropsy at the National Marine Mammal Laboratory, a porpoise, as well as a Baird's beaked whale that died following a naval exercise near the Olympic National Marine Sanctuary, showed evidence on CT scan consistent with hemorrhagic trauma that could be due to sonic pressure that would disorient and incapacitate the animals. The Navy is taking public comment until April 13 on possible expansion of the use of sonar in the Northwest.In a letter to the Navy, the Whale Museum board of directors asked that the Navy "incorporate better techniques to improve their detection rates of marine mammals, extend their exclusion zones around detected marine mammals, and utilize exclusion zones based on specific areas and times in their mitigation strategies.""The Navy can and should do better at knowing where marine mammals are within the Navy's training region. It would be preferable that a third party organization conduct this monitoring and that the sightings be reported and made available to the scientific and management communities," the letter states."If marine mammals are sighted or detected within acoustic range, then exercises should be shut down if in progress, and postponed or moved elsewhere if the exercises have not yet started ... Exercises that generate loud noise (active sonar, explosions) should not be conducted at night because visual detections of Southern Resident orcas or other marine mammals are not usually possible. "Exercises that generate loud noise (active sonar, explosions) should not be conducted in the inland waters (including the Strait of Juan de Fuca) because these form critical habitat for endangered Southern Resident killer whales and because this area already has so many anthropogenic noise sources."

By RICHARD WALKERJournal of the San Juans Editor

Court wrestles with case on Navy sonar, whales

The Supreme Court appeared divided Wednesday over how to resolve a long-running dispute over whether environmental laws may be used to limit the Navy's use of sonar to protect whales. The court heard arguments in the Bush administration's appeal of court rulings that restrict sonar in submarine-hunting naval training exercises off the Southern California coast. Sonar can interfere with whales' ability to navigate and communicate.The training is "vitally important" for sailors who may be deployed around the world in search of enemy submarines, Solicitor General Gregory Garre told the justices. Garre said there is scant evidence over 40 years of exercises off the Pacific Coast that the Navy's sonar harms whales and dolphins.Richard Kendall, a lawyer for the Natural Resources Defense Council, said the sonar's piercing sound was comparable to the noise of a jet engine magnified 2,000 times in the courtroom.A species of whales called beaked whales are particularly susceptible to harm from sonar, which can cause them to strand themselves onshore, Kendall said.The case left one justice, Stephen Breyer, wondering how a judge should balance national security concerns and environmental interests."You are asking us who know nothing about whales and less about the military to start reading all these documents to try to figure out who's right in the case where the other side says the other side is totally unreasonable," Breyer said.The exercises have continued since the 9th U.S. Circuit Court of Appeals in San Francisco ruled in February that the Navy must limit sonar use when ships get close to marine mammals.Kendall told the justices that the Navy is managing under the restrictions, saying eight of 14 planned exercises have been completed since the restrictions took effect.This round of training is scheduled to be completed by January.Separately, the Navy has agreed to similar limits on anti-submarine training off the coast of Hawaii to settle a lawsuit.But Garre said the issue for the court is whether federal judges should have stepped in to force changes to the training when the government's first environmental assessment found there was little prospect of harm.The Navy's own environmental assessment of using sonar during the 14 training exercises off the California coast found that it could disturb or harm an estimated 170,000 marine mammals, including possible temporary hearing loss in at least 8,000 whales.The administration also says the president has the power to override federal court rulings on environmental laws during emergencies that include harm to national security. The Navy says it already has taken steps to protect beaked whales, dolphins and other creatures and is balancing war training and environmental protections.Justice David Souter ridiculed the idea that the administration could declare an emergency to try to get around complying with environmental laws. The Navy opted not to conduct a more rigorous environmental study, an environmental impact study, before beginning the long-planned exercises, Souter said."If there's an emergency, it's one the Navy created simply by failing to start EIS preparation in a timely way," he said.Justices John Paul Stevens and Ruth Bader Ginsburg also suggested that the Navy could have avoided the court fight by producing the impact study before the exercises began.Justice Samuel Alito suggested that he found little evidence in the court record that the marine mammals would be harmed by the sonar use. Alito also said there was "something incredibly odd" that a single federal judge, who issued the first order against the Navy in this case, would be able to force changes in the exercises. Chief Justice John Roberts and Justice Antonin Scalia also appeared supportive of the government's case. An injunction by U.S. District Judge Florence-Marie Cooper in Los Angeles early this year created a 12-nautical-mile no-sonar zone along the coast and ordered the Navy to shut off all sonar use within 2,200 yards of a marine mammal. The 9th Circuit sided with the lower court and said the Navy must abide by the injunction. However, while the litigation was under way, the appeals court gave the Navy permission to use sonar closer than the restrictions allow during critical maneuvers. The case is Winter v. Natural Resources Defense Council, 07-1239.

U.S. Navy Sonar Linked To Whale Strandings, Environmental Scientists Argue

Earlier this summer, the U.S. Supreme Court agreed to review a series of lower court rulings that restrict the Navy's use of sonar in submarine detection training exercises off the coast of Southern California. The court is due to hear the case after its term begins again this month.

For many years, professor Chris Parsons has been tracking the patterns of mass whale strandings around the world. In his most recent paper, "Navy Sonar and Cetaceans: Just how much does the gun need to smoke before we act?" Parsons and his co-authors bring together all of the major whale and dolphin strandings in the past eight years and discuss the different kinds of species that have been affected worldwide. They also strongly argue for stricter environmental policies related to this issue.
"Generally, if there is a large whale stranding, there is a military exercise in the area," says Parsons. "Sonar is killing more whales than we know about."
Parsons is a national delegate for the International Whaling Commission’s scientific and conservation committees, and on the board of directors of the marine section of the Society for Conservation Biology. He has been involved in whale and dolphin research for more than a decade and has conducted projects in South Africa, India, China and the Caribbean as well as the United Kingdom.
Though Parsons believes that there is a good chance the U.S. Supreme Court will rule in favor of the Navy, he thinks there is a chance for a win-win situation on both sides.
"If the Navy uses proper mitigation efforts, it can still perform its exercises and affect less of the whale population," he says. However, he argues they need to avoid sensitive areas completely, and have trained, experienced whale experts as lookouts when performing these exercises—"not just someone who has watched a 45-minute DVD, which is sadly the only training most naval lookouts get with respect to finding and detecting whales."
Even with all these efforts, however, Parsons worries that sonar is affecting many more whales than we even know about. "Eventually the Navy may have to reconsider the use of certain types of sonar all together. They could be wiping out entire populations of whales, and seriously depleting others."
Journal reference:
Chris Parsons et al. Navy Sonar and Cetaceans: Just how much does the gun need to smoke before we act? Marine Pollution Bulletin, (in press)
Adapted from materials provided by George Mason University.

Sounds Travel Farther Underwater As World's Oceans Become More Acidic

It is common knowledge that the world's oceans and atmosphere are warming as humans release more and more carbon dioxide into the Earth's atmosphere. However, fewer people realize that the chemistry of the oceans is also changing—seawater is becoming more acidic as carbon dioxide from the atmosphere dissolves in the oceans.

According to a paper to be published this week by marine chemists at the Monterey Bay Aquarium Research Institute, these changes in ocean temperature and chemistry will have an unexpected side effect—sounds will travel farther underwater.
Conservative projections by the Intergovernmental Panel on Climate Change (IPCC) suggest that the chemistry of seawater could change by 0.3 pH units by 2050 (see below for background information on pH and ocean acidification). In the October 1, 2008 issue of Geophysical Research Letters, Keith Hester and his coauthors calculate that this change in ocean acidity would allow sounds to travel up to 70 percent farther underwater. This will increase the amount of background noise in the oceans and could affect the behavior of marine mammals.
Ocean chemists have known for decades that the absorption of sound in seawater changes with the chemistry of the water itself. As sound moves through seawater, it causes groups of atoms to vibrate, absorbing sounds at specific frequencies. This involves a variety of chemical interactions that are not completely understood. However the overall effect is strongly controlled by the acidity of the seawater. The bottom line is the more acidic the seawater, the less low- and mid-frequency sound it absorbs.
Thus, as the oceans become more acidic, sounds will travel farther underwater. According to Hester's calculations, such a change in chemistry will have the greatest effect on sounds below about 3,000 cycles per second (two and one half octaves above "middle C" on a piano).
This range of sounds includes most of the "low frequency" sounds used by marine mammals in finding food and mates. It also includes many of the underwater sounds generated by industrial and military activity, as well as by boats and ships. Such human-generated underwater noise has increased dramatically over the last 50 years, as human activities in the ocean have increased.
The MBARI researchers say that sound already may be traveling 10 percent farther in the oceans than it did a few hundred years ago. However, they predict that by 2050, under conservative projections of ocean acidification, sounds could travel as much as 70 percent farther in some ocean areas (particularly in the Atlantic Ocean). This could dramatically improve the ability of marine mammals to communicate over long distances. It could also increase the amount of background noise that they have to live with.
There are no long-term records of sound absorption over large ocean areas. However, the researchers cite a study off the coast of California that showed an increase in ocean noise between 1960 and 2000 that was not directly attributable to known factors such as ocean winds or ships.
Hester's research shows once again how human activities are affecting the Earth in far-reaching and unexpected ways. As the researchers put it in their paper, "The waters in the upper ocean are now undergoing an extraordinary transition in their fundamental chemical state at a rate not seen on Earth for millions of years, and the effects are being felt not only in biological impacts but also on basic geophysical properties, including ocean acoustics."
This research was supported by grants from the David and Lucile Packard Foundation.
Ocean acidification: background information
Over the last century, cars, power plants, and a variety of human activities have released hundreds of billions of tons of carbon dioxide (CO2) into the Earth's atmosphere. In analyzing the effects of this planet-wide chemistry experiment, scientists discovered that about half of this CO2 has been absorbed by the world's oceans. In the last five or ten years, chemical oceanographers have come to the conclusion that adding carbon dioxide to the oceans has caused them to be more acidic, just as adding carbon dioxide to water causes the resulting soda water to become more acidic.
Chemists measure acidity using pH units, with a scale that runs from 0 (the most acidic) to 14 (the least acidic, or most basic). Neutral tap water, for example, has a pH of about 7. For comparison, lemon juice has a pH of about 2 and the acid in your car battery might have a pH of 0.8. Seawater, on the other hand, is usually slightly basic, with a pH of about 8.1.
Marine chemists (including MBARI's Peter Brewer) estimate that the pH of the world's oceans has already dropped by about 0.1 pH units since the beginning of the industrial revolution, about 250 years ago. They further estimate that the pH of the ocean may drop by another 0.2 pH units (to 7.9) by the year 2050. This may not seem like much of a change, but it could have significant impacts on corals and other marine organisms whose body chemistry is adapted to millions of years of relatively constant chemical conditions.
Journal reference:
K. C. Hester, E. T. Peltzer, W. J. Kirkwood, and P. G. Brewer. Unanticipated consequences of ocean acidification: A noisier ocean at lower pH. Geophysical Research Letters, Vol. 35, No. 31 (October 1, 2008)
Adapted from materials provided by Monterey Bay Aquarium Research Institute.

Discovering How Human-caused Sounds Affect Marine Mammals

The Marine Board-ESF published its 13th Position Paper, which presents a view from marine mammal specialists on the research needed to assess the effects of anthropogenic sound upon marine mammals.*

Marine mammals are an important component in the food-chain of the marine biotope. They rely largely on sound for their communication and organisation, but these mechanisms are not completely understood.
The proposed research strategy is of key importance because both marine mammals and many economically important sea-based activities are at risk because of a lack of information about the effects of anthropogenic sound on marine mammals.
Human activities produce a range of underwater sound frequencies that can interfere with marine mammal functions important for their survival.
Use of sound in the ocean has increased due to a growing number of scientific and military applications (e.g. seabed mapping, naval sonar) and many economic ocean-based activities such as oil exploitation and fisheries. This concern has triggered a number of investigations on the impacts of man-made sound on marine mammals, but to date, there has been no structured analysis of the full research challenge it presents.
“A scientific research strategy is clearly needed. First of all, interaction between anthropogenic sound and marine mammals is a complex problem, as the effects of anthropogenic sound on marine mammals depend on many aspects, such as intensity and frequency of sounds, marine mammal species and their age, environmental conditions, etc. In addition, the physiological effects of sound in the oceans are not clearly understood.” says Marine Board Chair Lars Horn.
In its global assessment of cetacean species, released in august 2008, the International Union for the Conservation of Nature (IUCN) concluded that ocean noise posed a significant threat. These concerns have reached the larger public through exposure in popular press and media.
In spite of growing attention, defining and implementing measures to reduce the impacts of man-made sound on marine mammals remain seriously hindered by a lack of knowledge.
“There is a need to rapidly improve the state of knowledge by new research focussed on specific questions of high priority. This requires concerted, coordinated action across many expert groups within the scientific community” says Expert Group Chair Ian Boyd.
A key message of the Marine Board Position Paper is that a risk assessment framework needs to be used to define where the research effort can be applied with greatest effect.
The Position Paper concludes that to construct a full risk assessment, it is necessary to be able to make all the linkages between issues from sound production, through behaviour change, effects on life function and the effects on populations. In particular, there is a need to improve knowledge of how effects on life function influence vital rates.
The analysis presented in the Position Paper is a first step towards defining a full research strategy and will need further review and modification as additional intellectual attention is applied to this field.
*The research strategy presented in Marine Board Position Paper 13 results from the activities and proceedings of an Expert Group on anthropogenic sound and marine mammals convened at the joint European Marine Board and National Science Foundation (US) Workshop at Tubney House on October 4-8 2005 in Oxford, with financial and logistical support of the Marine Board.
Position paper: The Effects of Anthropogenic Sound on Marine Mammals
Adapted from materials provided by European Science Foundation.

Navy Conducts Hearing Tests On Whale

A team of U.S. Navy audiologists conducted a hearing test Saturday on a rare beaked whale convalescing at a marine mammal rehabilitation center in the Florida Keys. The mature female whale has been tentatively identified as a Gervais' beaked whale or a Sowerby's beaked whale, said Dorian Houser, a consulting biologist with the Navy Marine Mammal Program in San Diego. The whale was discovered Friday in shallow waters behind a home in Islamorada. It was transported to the Marine Mammal Conservancy in Key Largo. Houser and Navy staff scientist James Finneran made a trip to the conservancy Saturday to establish a hearing baseline measure for the whale -- something that has only been done once for a Gervais' and never for a Sowerby's. That gives them data they can use for comparison purposes in the future. "These animals are very rare," Houser said. "Usually when you find one stranded, it's dead." Researchers were taking blood samples from the 14-foot-long, 1,595-pound whale to try to determine why it stranded. It also was being rehydrated with fluids through a tube in its stomach every four hours. Source: Associated Press

Migrating Squid Drove Evolution Of Sonar In Whales And Dolphins,

Behind the sailor's lore of fearsome battles between sperm whale and giant squid lies a deep question of evolution: How did these leviathans develop the underwater sonar needed to chase and catch squid in the inky depths?Now, two evolutionary biologists at the University of California, Berkeley, claim that, just as bats developed sonar to chase flying insects through the darkness, dolphins and other toothed whales also developed sonar to chase schools of squid swimming at night at the surface.Because squid migrate to deeper, darker waters during the day, however, toothed whales eventually perfected an exquisite echolocation system that allows them to follow the squid down to that "refrigerator in the deep, where food is available day or night, 24/7," said evolutionary biologist David Lindberg, UC Berkeley professor of integrative biology and coauthor of a new paper on the evolution of echolocation in toothed whales published online July 23 in advance of its publication in the European journal Lethaia."When the early toothed whales began to cross the open ocean, they found this incredibly rich source of food surfacing around them every night, bumping into them," said Lindberg, former director and now a curator in UC Berkeley's Museum of Paleontology. "This set the stage for the evolution of the more sophisticated biosonar system that their descendents use today to hunt squids at depth."Lindberg and coauthor Nick Pyenson, a graduate student in the UC Berkeley Department of Integrative Biology and at the Museum of Paleontology, reconstructed this scenario after looking at both whale evolution and the evolution of cephalopods like squid and nautiloids - relatives of today's chambered nautilus - and relating this to the biology of living whales and cephalopods.All toothed whales, or odontocetes, echolocate. The baleen whales, which sieve krill from the ocean and have no teeth, do not. The largest of the toothed whales, the sperm whale, grows up to 60 feet long and dives to 3,000 meters - nearly two miles - in search of squid. Though poorly known because they live entirely in the deep ocean, the many species of the beaked whale dive nearly as deep. Belugas and narwhals descend beyond 1,000 meters, while members of the dolphin family - porpoises, killer whales and pilot whales, for example - all can dive below the 200-meter mark where sunlight is reduced to darkness.According to Pyenson, who focuses on the evolution of whales, the first whales entered the ocean from land about 45 million years ago, and apparently did not echolocate. Their fossil skeletons do not have the scooped forehead of today's echolocating whales, which cups a fatty melon-shaped ball that is thought to act as a lens to focus clicking noises.Skulls with the first hints of a concave forehead and potential sound-generating bone structures arose about 32 million years ago, Pyenson said, by which time whales presumably had spread throughout the oceans. Whales had developed underwater hearing by about 40 million years ago.According to Lindberg, whale biologists had various theories about echolocation, including that whales developed this biosonar soon after entering the water as a way to find food in turbid rivers and estuaries. The evolution of toothed whales, however, indicates otherwise. Whales first occupied the ocean, and only later invaded rivers. Other experts have proposed that development of echolocation coincided with global cooling around 33.5 million years ago, though a mechanism was not specified.The most convincing explanation, that echolocation allowed whales to more efficiently find food in the darkness of the deep ocean, ignores the question of evolution."How did the whales know there was a large supply of food down in the dark?" asked Lindberg, noting that cephalopods are the most abundant and high-energy resource in the ocean, eaten by 90 percent of all toothed whales. "What were the intermediate evolutionary steps that got whales down there?"Lindberg, a specialist in the evolution of marine mollusks, noted that cephalopods have migrated up and down on a daily "diel" cycle for at least 150 million years. At the time whales developed biosonar, nautiloids dominated the oceans. Lindberg and Pyenson propose that whales first found it possible to track these hard-shelled creatures in surface waters at night by bouncing sounds off of them, an advantage over whales that relied only on moonlight or starlight. This would have enabled whales to follow the cephalopods as they migrated downwards into the darkness during the day. Today, the largest number of squid hang out during the day at about 500 meters below the surface, though some go twice as deep. During the night, however, nearly half the squid are within 150 meters of the surface.Over the millennia, cephalopod species in general - and especially shelled cephalopod species - fell as the number of whale species boomed, possibly because of predation by whales. Then, about 10 million years ago, the whales seem to have driven the nautiloids out of the open ocean into protected reefs. Lindberg said that the decline in nautiloid diversity would have forced whales to perfect their sonar to hunt soft-bodied, migrating squid, such as the Teuthida, which in the open ocean are typically two feet long or bigger and range up to the 40-foot-long giant squid."Whales didn't need to have a very sophisticated sonar system to follow the nautiloids, they could just home in on the hard part," Lindberg said. Only later , he added, did they "develop a complex system with finer resolution to detect and capture soft-bodied squid.""Whales, like bats, developed a sensory system for seeing with sound, and every single toothed whale echolocates in a different way, just like how different bat species echolocate in different ways," Pyenson said. Whales also partition the water column, specializing in harvesting squid at specific depths, just as bats partition the tree canopy and preferentially hunt insects at specific heights.Lindberg noted that whales and bats are strong examples of convergent evolution to take advantage of unexploited food resources: nocturnal insects, in the case of non-migrating insectivorous bats, and nocturnal cephalopods, in the case of whales. And just as predominately migrating fruit bats do not echolocate, so filter-feeding baleen whales that depend on dense seasonal resources lack biosonar.Lindberg and Pyenson used existing data on whales and cephalopods to reach their conclusions, drawing upon aspects of tectonics, paleontology, physiology, ecology, anatomy and biophysics. In the same way, "thinking from an evolutionary perspective about existing data from biology, paleontology and ecology could answer questions about the origin of echolocation in bats, shrews and other animals," Lindberg said.The work was supported in part by the Remington Kellogg Fund and the Doris O. and Samuel P. Welles Research Fund of the UC Berkeley Museum of Paleontology and by a graduate research fellowship from the National Science Foundation.

Appeals court OKs Navy use of sonar

The Navy can use high-powered sonar during exercises off the Southern California coast, despite the technology's threat to whales and other marine mammals, a federal appeals court ruled Friday. National security interests outweigh the possible harm to marine life, a three-judge panel of the 9th U.S. Circuit Court of Appeals determined in overturning a judge's order banning the practice."The public does indeed have a very considerable interest in preserving our natural environment and especially relatively scarce whales," Judge Andrew Kleinfeld wrote for the majority. "But it also has an interest in national defense. We are currently engaged in war, in two countries."Judge Milan Smith Jr. disagreed, writing that he would have kept the ban in place in part because the Natural Resources Defense Council is likely to win its lawsuit to stop the use of sonar.The ruling allows the Navy to use high-powered sonar in 11 planned training exercises.Cara Horowitz, an attorney for the Santa Monica-based resources defense council, said she was disappointed by the ruling but remained confident the lawsuit would succeed in shutting down or easing the effects of the sonar program off the Southern California coast.The council alleges the Navy's sonar causes whales to beach themselves, among other environmental harms.The Navy maintains it already minimizes risks to marine life and has monitored the ocean off Southern California for the 40 years it has used sonar without seeing any whale injuries. The service says the sonar is vital for tracking submarines.

California Coastal Commission Limits U.S. Navy Sonar Use

LOS ANGELES, California, January 16, 2007 (ENS) - The California CoastalCommission has decided to approve two years of naval exercises off SouthernCalifornia but only if the U.S. Navy puts in place measures to protectmarine mammals from potentially lethal effects of noisy mid-frequency sonar.The vote taken Thursday represents the first time the Navy had sought theCommission's approval for mid-frequency sonar training, and the first timeCalifornia has imposed safety conditions for such exercises. The exercises will take place in waters off the continental United Statesthat host blue whales, humpbacks, gray whales, dolphins, porpoises and othersensitive species. "We don't have to choose between naval training and the protection of whalesand other marine life," said Cara Horowitz, a project attorney with theMarine Mammals Program at the Natural Resources Defense Council, NRDC. "Whenheld to sound standards, the Navy has shown again and again that it cantrain effectively while minimizing risk to the marine environment." Whales around the world have been found dead or dying following encounterswith mid-frequency military sonar that fills the water with loud pulses ofsound.