Blue whales singing in a lower key

Pulled from the LOS ANGELES TIMES by By Jill Leovy

Blue whales have changed their songs.

It’s the same old tune, but the pitch of the blues is mysteriously lower — especially off the coast of California where, local researchers say, the whales’ voices have dropped by more than half an octave since the 1960s.

No one knows why. But one conjecture is that more baritone whales indicate healthier populations: The whales may be less shrill because they’re less scarce and don’t have to pipe up to be heard by neighbors.

The discovery was accidental. Whale acoustics researcher Mark McDonald was trying to track blue whales’ movements using data from Navy submarine detectors. He had created a program to filter out the blues’ songs from a din of ocean noise captured by these instruments.

But he kept having to rewrite the code. Each year, it seemed, the whales sang at a lower pitch.

At first, the researchers thought it was a quirk. But after a couple of years of adjusting for lower frequencies, “we knew there was something strange going on,” said John Hildebrand, an oceanographer at Scripps Institution of Oceanography in San Diego and co-author of the study published recently in Endangered Species Research.

So the researchers scoured military data and seismograph readings for clues about what blue whales used to sound like.

A retired Navy scientist directed Hildebrand to a trove of tapes stored at Sea World. The delicate old reels were the size of dinner plates. It turned out they contained snippets of blue whale songs from 40 years ago.

The tapes eliminated all doubt: In the Beach Boys’ era, blue whales’ voices, while nowhere near falsetto, had been distinctly higher pitched.

With more work, the researchers were able show that blue whales worldwide are using deeper voices lately. Some have dropped their calls by only a few tones, but all showed a steady decline. “It was baffling,” Hildebrand said.

Blue whales are shrouded in mystery as it is. Sleek, mottled and silvery, they are rare and don’t reveal much. They don’t leap on the surface as much as humpback whales do. They might, if really flustered, slap their tails on the water. More often, they quietly sink, Hildebrand said.

Their song is barely audible to the human ear — a deep bass growl with very long wavelengths befitting very long whales.

The tone is so deep that if played in a small room, it’s hard to hear: The long-period sound waves extend beyond the walls. But play a recording very loudly, in a large auditorium, and “you feel it in your chest as much as you hear it,” McDonald said. “It’s awesome.”

The researchers pondered possible causes. Warmer temperatures? More acidic seas? Such factors affect the way sound moves through water, but not enough to explain the change, Hildebrand said.

The rumble of shipping traffic is thought to affect marine mammals. But the researchers argue that if whales were just trying to be heard above the fray, they would adopt higher, not lower, voices.

It’s also possible that the low voice is just a fad. Biologists talk about whale “culture,” and blue whales tend to be conformists. But researchers have said they doubt that a random, learned behavior could spread all over the globe.

So they put themselves in the whales’ shoes. McDonald surmised that whales would rather not sing in higher voices if they didn’t have to. They prefer deep and manly — “a lower, sexier frequency,” he said.

Among whales, he said, depth of voice may bespeak more desirable mates with larger bodies. It’s useful shorthand, since it’s hard to get a good look at one’s suitor if he is 80 feet long and swimming in murky water.

After the whales were hunted nearly to extinction, they may have been spread so thin that they could no longer find one another easily, prompting them to raise their pitch.

Efforts to restrict whaling beginning in the late ’60s helped populations rebound. With increased numbers, the whales may not have needed to shout and may have gradually returned to their deep tones.

“This hints that some of these great whales are recovering; it’s not all doom,” said co-author Sarah Mesnick, ecologist at the National Oceanic and Atmospheric Administration Fisheries Service.

If whale songs are related to population density, they might aid efforts to count blue whales, Hildebrand said. They once numbered in the hundreds of thousands. Today, their population is thought to be 10,000 or so.

Oceanographer Jay Barlow, program leader at NOAA fisheries, cautioned that changes in the whales’ pitch don’t track closely with population changes. California blues, for example, recovered most strongly in the ’70s and ’80s, and their numbers may not have grown much since, he said.

But Barlow had no alternate theory for the deeper songs, which he sometimes plays on his home stereo. The sound makes his floor shake and upsets his cats.

David Mellinger, a marine mammal bio-acoustician at Oregon State University, said that, whatever the reason, the finding “is astonishing.” It recalled to him the first time he heard a blue whale sing.

He was on a boat, using headphones, and one passed. “It was a defining moment in my life,” he said. “It made a visceral impression on me. Just this huge animal. I could hear the hugeness of it.”

As of June 23, 2008, the Supreme Court accepted a request by the United States Navy to review a series of lower court rulings that restrict the Navy’s use of sonar in training exercises off the coast of Southern California. Originating in August of 2007 a U.S. Court in Los Angeles was later amended, in February the Ninth Circuit Court of Appeals was affirmed. In March, the Navy requested the review that was finally accepted. The court-impossed mid-frequency active sonar training restrictions include a requirement to shut down sonar altogether when marine mammals are within 2,200 yards of any sonar source. They are also requested to reduce sonar power by 75% when the Navy detects significant surface ducting conditions, regardless of if a marine mammal is present. The shut down of 2.200 yards is 11 times larger than the existing shutdown distance that the Navy developed in consultation with the National Marine Fisheries Service. If  the requirement  to reduce sonar power by the 75% regardless of whether the marine mammals are present or not, will prevent Navy strike groups from conducting training to detect submarines in the same conditions in which submarines seek to hide. The Navy is in a very difficult place, they are attempting to balance between the need for an effective combat force and protecting the environment. The Navy is making a considerable investment in the science, $26 million dollars on marine mammal research so far this year. 

Currently the U.S. Navy is actively researching the historical trends of marine mammals to ensure the effects on them are as minimal as possible. Not only is the U.S. Navy looking into the history, but they are also attempting to begin using active sonar to protect not only the marine mammals but the sailors as well. 

Although the Navy does realize that sonar may affect some marine mammals under certain conditions, there are many other sounds and factors in the ocean environment that will be likely to have a greater impact. Some people believe that this sonar activity is a major cause of marine mammal strandings, though there is not any very circumstantial evidence of this sonar involvement. In all reality, sonar-related strandings occur very rarely; and when placed into context with the thousands of other strandings around the world there are many other factors that are causing them while other factors are still being ignored. Some of the causes of them that are very often overlooked are things such as fishery entanglements, pollution, disease, parasite infestation, ship strikes, trauma, and starvation as well. Naturally there are also going to be some strandings due to the weather or oceanographic events. The United Nations Environment Programme (UNEP) has recently publicized a report stating that sonar is rated last among the current threats to marine mammals. Sonar was only reported to threaten about 4% of the species, while 70% are endangered by fishing, and another 56% is threatened by the immense amount of pollution. 

Around 128  U.S. Navy ships and approximately 22 U.S. Navy submarines occupy the world’s oceans daily, and currently 90, or 58%,  of the Navy’s ships and subs are equipped with the active sonar. Though the Navy would prefer to use passive sonar so that they are not as actively detected as they would be while using the active sonar, the active sonar is used only about 1% of the time. The worldwide naval use of active sonar has been directly correlated with stranding deaths of approximately 40 whales within a 10 year period, from 1996-2006. As is stated in the information I’ve found, “this is only about 1/4 of 1% of the 3500+ strandings that occur each year on the U.S. shores.” Scanning for animals with passive sonar allow for the trained shipboard lookouts and available airborne assets prior to commencing on an exercise or any type of other events that the Navy may need to handle. The U.S. Navy has also reduced sonar levels by 75% if marine mammals are detected within 1,000 meters of the vessel’s sonar dome, and by 90% if a marine mammal is detected within 500 meters. They also cease the use of active sonar if a marine mammal is detected within 200 yards of an active source. 

The Navy is also regularly researching marine mammals, as they are the world leader in this research spend over $18 million annually on these research programs. In 2004 and 2005 the U.S. Navy-funded research produced approximately 65 peer-reviewed articles in professional journals. All this research done by the Navy has been favorably reviewed by three National Research Council panels over the past 6 years. Not only reviewed by the National Research Council, the research has also been reviewed by panels of independent experts, during the same time period, that also returned strongly favorable conclusions concerning the quality of the research emerging from the program. 

Note: The Navy’s policy is to operate in compliance with environmental  laws. To this end, we analyze the potential effects of our training and operations on the environment and cooperate with environmental regulatory agencies as appropriate based on those effects. We seek authorization from the National Marine Fisheries Service under the Marine Mammal Protection Act, and/or consult with regulators under the Endangered Species Act, as required for our military readiness activities.

Supreme Court Accepts Navy Sonar Requests