Constantine Alexander's blog

H1N1 discovered in marine mammals

Northern Elephant Seal (Mirounga angustirostris), Piedras Blancas, San Simeon, CA. Photo by Michael "Mike" L. Baird

Scientists at the University of California, Davis, detected the H1N1 (2009) virus in free-ranging northern elephant seals off the central California coast a year after the human pandemic began, according to a study published today, May 15, in the journal PLOS ONE. It is the first report of that flu strain in any marine mammal.

"We thought we might find influenza viruses, which have been found before in marine mammals, but we did not expect to find pandemic H1N1," said lead author Tracey Goldstein, an associate professor with the UC Davis One Health Institute and Wildlife Health Center. "This shows influenza viruses can move among species."

UC Davis researchers have been studying flu viruses in wild birds and mammals since 2007 as part of the Centers of Excellence in Influenza Research and Surveillance program funded by National Institutes of Health. The goal of this research is to understand how viruses emerge and move among animals and people.

Between 2009 and 2011, the team of scientists tested nasal swabs from more than 900 marine mammals from 10 different species off the Pacific Coast from Alaska to California. They detected H1N1 infection in two northern elephant seals and antibodies to the virus in an additional 28 elephant seals, indicating more widespread exposure.

Neither infected seal appeared to be ill, indicating marine mammals may be infected without showing clinical signs of illness.

The findings are particularly pertinent to people who handle marine mammals, such as veterinarians and animal rescue and rehabilitation workers, Goldstein said. They are also a reminder of the importance of wearing personal protective gear when working around marine mammals, both to prevent workers' exposure to diseases, as well as to prevent the transmission of human diseases to animals.

H1N1 originated in pigs. It emerged in humans in 2009, spreading worldwide as a pandemic. The World Health Organization now considers the H1N1 strain from 2009 to be under control, taking on the behavior of a seasonal virus.

"H1N1 was circulating in humans in 2009," said Goldstein. "The seals on land in early 2010 tested negative before they went to sea, but when they returned from sea in spring 2010, they tested positive. So the question is where did it come from?"

When elephant seals are at sea, they spend most of their time foraging in the northeast Pacific Ocean off the continental shelf, which makes direct contact with humans unlikely, the report said.

The seals had been satellite tagged and tracked, so the researchers knew exactly where they had been and when they arrived on the coast. The first seal traveled from California on Feb. 11 to southeast Alaska to forage off the continental shelf, returning to Point Piedras Blancas near San Simeon, Calif., on April 24. The second seal left Ano Nuevo State Reserve in San Mateo County, Calif., on Feb. 8, traveling to the northeast Pacific and returning on May 5. Infections in both seals were detected within days of their return to land. The report said exposure likely occurred in the seals before they reached land, either while at sea or upon entering the near-shore environment.

The research, led by scientists Goldstein and Walter Boyce at the UC Davis School of Veterinary Medicine's One Health Institute, was conducted with collaborators Nacho Mena and Adolfo Garcia-Sastre at the Icahn School of Medicine at Mount Sinai in New York, who sequenced the virus isolates and characterized their phenotypic properties.

"The study of influenza virus infections in unusual hosts, such as elephant seals, is likely to provide us with clues to understand the ability of influenza virus to jump from one host to another and initiate pandemics," said Garcia-Sastre, professor of microbiology and director of the Global Health and Emerging Pathogens Institute at the Icahn School of Medicine.

The research was funded primarily through the Centers of Excellence for Influenza Research and Surveillance, a program supported by the National Institute of Allergy and Infectious Disease, and the Tagging of Pacific Predators program, a project of the Census of Marine Life.

Contact: Tracey Goldstein
tgoldstein@ucdavis.edu
530-752-0412
University of California - Davis

UC Davis School of Veterinary Medicine: As a top veterinary school internationally, and a leader in preventive medicine and wildlife health, UC Davis has an extensive research and training record in the fields of epidemiology, surveillance, zoonotic diseases, comparative medicine, diagnostics, wildlife pathogens and conservation, food safety, disease prevention and outbreak response. The school has trained more than 800 international veterinarians from 75 countries, including hot spots in Africa, Latin America and Asia. Its One Health Institute and Wildlife Health Center manage One Health programs for people and animals ranging from the Pacific Northwest to Africa's Congo Basin and Rift Valley.

Using earthquake sensors to track endangered whales

Fin whale surfacing in Greenland. Photo by Aqqa Rosing-Asvid. (CC)

The fin whale is the second-largest animal ever to live on Earth. It is also, paradoxically, one of the least understood. The animal's huge size and global range make its movements and behavior hard to study.

A carcass that washed up on a Seattle-area beach this spring provided a reminder that sleek fin whales, nicknamed "greyhounds of the sea," are vulnerable to collision when they strike fast-moving ships. Knowing their swimming behaviors could help vessels avoid the animals. Understanding where and what they eat could also help support the fin whale's slowly rebounding populations.

University of Washington oceanographers are addressing such questions using a growing number of seafloor seismometers, devices that record vibrations. A series of three papers published this winter in the Journal of the Acoustical Society of America interprets whale calls found in earthquake sensor data, an inexpensive and non-invasive way to monitor the whales. The studies are the first to match whale calls with fine-scale swimming behavior, providing new hints at the animals' movement and communication patterns.

The research began a decade ago as a project to monitor tremors on the Juan de Fuca Ridge, a seismically active zone more than a mile deep off the Washington coast. That was the first time UW researchers had collected an entire year's worth of seafloor seismic data.

"Over the winter months we recorded a lot of earthquakes, but we also had an awful lot of fin-whale calls," said principal investigator William Wilcock, a UW professor of oceanography. At first the fin whale calls, which at 17 to 35 vibrations per second overlap with the seismic data, "were kind of just a nuisance," he said.

In 2008 Wilcock got funding from the Office of Naval Research to study the previously discarded whale calls.

A seismometer inserted into a hole drilled in seafloor lava. Eight of these instruments were installed at an ocean spreading-center volcano 150 miles off Vancouver Island. A data recording device is enclosed in the yellow sphere. In three years of operation the network detected nearly 40,000 small earthquakes, and hundreds of thousands of fin-whale calls. Photo credit: John Delaney and Deborah Kelley, UW (taken with remotely operated vehicle Jason)

Dax Soule, a UW doctoral student in oceanography, compared the calls recorded by eight different seismometers. Previous studies have done this for just two or three animals at a time, but the UW group automated the work to analyze more than 300,000 whale calls.

The method is similar to how a smartphone's GPS measures a person's location by comparing paths to different satellites. Researchers looked at the fin whale's call at the eight seismometers to calculate a position. That technique let them follow the animal's path through the instrument grid and within 10 miles of its boundaries.

Soule created 154 individual fin whale paths and discovered three categories of vocalizing whales that swam south in winter and early spring of 2003. He also found a category of rogue whales that traveled north in the early fall, moving faster than the other groups while emitting a slightly higher-pitched call.

"One idea is that these are juvenile males that don't have any reason to head south for the breeding season," Soule said. "We can't say for sure because so little is known about fin whales. To give you an idea, people don't even know how or why they make their sound."

The fin whale's call is not melodic, but that's a plus for this approach. The second-long chirp emitted roughly every 25 seconds is consistently loud and at the lower threshold of human hearing, so within range of earthquake monitoring instruments. These loud, repetitive bleeps are ideally suited for computer analysis.

Michelle Weirathmueller, a UW doctoral student in oceanography, used Soule's triangulations to determine the loudness of the call. She found the fin whale's call is surprisingly consistent at 190 decibels, which translates to 130 decibels in air – about as loud as a jet engine.

Knowing the consistent amplitude of the fin whale's song will help Weirathmueller track whales with more widely spaced seismometer networks, in which a call is recorded by only one instrument at a time. Those include the Neptune Canada project, the U.S. cabled observatory component of the Ocean Observatories Initiative, and the huge 70-seismometer Cascadia Initiative array that's begun to detect tremors off the Pacific Northwest coast.

"We'd like to know where the fin whales are at any given time and how their presence might be linked to food availability, ocean conditions and seafloor geology," Weirathmueller said. "This is an incredibly rich dataset that can start to pull together the information we need to link the fin whales with their deep-ocean environments."

Contact: Hannah Hickey
hickeyh@uw.edu
206-543-2580
University of Washington

Researchers track singing humpback whales on a Northwest Atlantic feeding ground

Humpback whales in the Northwest Atlantic. Credit: NEFSC/NOAA

Male humpback whales sing complex songs in tropical waters during the winter breeding season, but they also sing at higher latitudes at other times of the year. NOAA researchers have provided the first detailed description linking humpback whale movements to acoustic behavior on a feeding ground in the Northwest Atlantic.

Findings from the study, published April 10 in the journal PLOS ONE, demonstrate the potential applications of passive acoustic tracking and monitoring for marine mammal conservation and management.

Co-author Sofie Van Parijs, who heads the passive acoustics group at the Woods Hole Laboratory of NOAA's Northeast Fisheries Science Center (NEFSC), says this study is not so much about biology, but about acoustic methods.

"We have monitored and acoustically recorded whale sounds for years, and are now able to 'mine' these data using new computer software applications and methods, " said Van Parijs. "Passive acoustic tracking has enabled us to localize humpback whale song to study the movements of individual whales, and to relate the singing to specific behaviors. This has never before been accomplished for singing humpbacks on a northwest Atlantic feeding ground."

"Passive acoustic tracking of humpback whales and other cetacean species provides an opportunity to collect data on movement patterns that are difficult―or impossible―to obtain using other techniques," said lead author Joy Stanistreet, who worked with Van Parjis and co-author Denise Risch at the NEFSC's Woods Hole Laboratory at the time of the study. Stanistreet is currently a graduate student at the Duke University Marine Laboratory in Beaufort, N.C.

Map of the Stellwagen Bank National Marine Sanctuary. CredIt: USGS.

Since 2007, NEFSC researchers have used year-round passive acoustic monitoring to study ocean noise in the Stellwagen Bank National Marine Sanctuary, a feeding ground for humpback whales and other marine mammal species in the southern Gulf of Maine. Humpback whales typically frequent the sanctuary between April and December and feed on sand lance and other small schooling fish. Humpback whale singing in the sanctuary usually occurs from April through May, following the spring migration from southern waters, and from August to December before the return fall migration. During the summer, humpbacks remain in the sanctuary but generally do not sing while they feed.

The researchers used data from acoustic recordings collected from an array of 10 bottom-mounted marine autonomous recording units (MARUs). Continuous 24-hour recordings units were deployed in the sanctuary for four consecutive three-month periods during 2009. The MARUs were placed three to six miles apart, and the arrays shifted seasonally to areas within the sanctuary having high whale concentrations.

Humpback whale songs were recorded in distinct time periods during spring and fall. No songs were recorded during summer and winter, although humpback whales remained in the area. Songs were most common in the spring, and occurrences of singing increased significantly before and after migration periods.

Forty-three song sessions, each lasting from 30 minutes to eight hours, were used to track individual singing whales. Most of the singers were actively swimming; the patterns and rates of their movement ranged from slow meandering to a faster directional movement. In one case, two singers were tracked at the same time, suggesting a potential reaction by one singer to the presence of the other.

Marine mammal researchers could also use passive acoustic localization and tracking methods to better understand the geographic distribution, abundance, and densities of cetacean species, many of which are threatened by human activities. These applications may help inform and enhance marine mammal conservation and management efforts.

The study was funded by the National Oceanographic Partnership Program, a collaboration of federal agencies that provides leadership and coordination of national oceanographic research and education initiatives.

Citation: Stanistreet JE, Risch D, Van Parijs SM (2013) Passive Acoustic Tracking of Singing Humpback Whales (Megaptera novaeangliae) on a Northwest Atlantic Feeding Ground. PLoS ONE 8(4): e61263. doi:10.1371/journal.pone.0061263

Contact: Shelley Dawicki
shelley.dawicki@noaa.gov
504-495-2378
NOAA Northeast Fisheries Science Center

Whales able to learn from others

Humpbacks pass on hunting tips

Humpback whales.

Humpback whales are able to pass on hunting techniques to each other, just as humans do, new research has found.

A team of researchers, led by the University of St Andrews, has discovered that a new feeding technique has spread to 40 per cent of a humpback whale population.

The findings are published today (Thursday 25 April) by the journal Science.

The community of humpback whales off New England, USA, was forced to find new prey after herring stocks – their preferred food - crashed in the early 1980s.

The solution the whales devised – hitting the water with their tails while hunting a different prey – has now spread through the population by cultural transmission. By 2007, nearly 40 per cent of the population had been seen doing it.

Dr Luke Rendell, lecturer in the School of Biology at the University of St Andrews, said: "Our study really shows how vital cultural transmission is in humpback populations – not only do they learn their famous songs from each other, they also learn feeding techniques that allow them to buffer the effects of changing ecology."

The team - also including Jenny Allen from the University of St Andrews, Mason Weinrich of the Whale Center of New England and Will Hoppitt from Anglia Ruskin University - used a new technique called network-based diffusion analysis to demonstrate that the pattern of spread followed the network of social relationships within the population, showing that the new behaviour had spread through cultural transmission, the same process that underlies the diversity of human culture.

The data were collected by naturalist observers aboard the many whale-watching vessels that patrol the waters of the Gulf of Maine each summer.

Dr Hoppitt said: "We can learn more about the forces that drive the evolution of culture by looking outside our own ancestral lineage and studying the occurrence of similar attributes in groups that have evolved in a radically different environment to ours, like the cetaceans."

Humpbacks around the world herd shoals of prey by blowing bubbles underwater to produce 'bubble nets'.

The feeding innovation, called 'lobtail feeding', involves hitting the water with the tail before diving to produce the bubble nets.

Lobtail feeding was first observed in 1980, after the stocks of herring, previously the main food for the whales, became depleted.

At the same time sand lance stocks soared, and it would seem the innovation is specific to that particular prey, because its use is concentrated around the Stellwagen Bank, spawning grounds where the sand lance can reach high abundance.

Using a unique database spanning thirty years of observations gathered by Dr Weinrich, the researchers were able track the spread of the behaviour through the whales' social network.

Jenny Allen said: "The study was only made possible because of Mason's dedication in collecting the whale observations over decades, and it shows the central importance of long-term studies in understanding the processes affecting whale populations."

The scientists believe their results strengthen the case that cetaceans - the whales and dolphins - have evolved sophisticated cultural capacities.

The skills, knowledge, materials and traditions that humans learn from each other help explain how we have come to dominate the globe as a species, but how we evolved the capabilities to transmit such knowledge between ourselves remains a mystery that preoccupies biologists, psychologists and anthropologists.

Contact: Fiona MacLeod
fm43@st-andrews.ac.uk
44-133-446-2108
University of St. Andrews

Sea mammals find US safe harbor

California Sea Lions (Zalophus californianus), Monterey Bay, California, USA
by Kevin Schafer, Seattle, Washington, USA 

In 1972, a U.S. Senate committee reported, "Many of the great whales which once populated the oceans have now dwindled to the edge of extinction," due to commercial hunting. The committee also worried about how tuna fishing was accidentally killing thousands of dolphins, trapped in fishing gear. And they considered reports about seal hunting and the decline of other mammals, including sea otters and walruses.

In October of that year, Congress passed the Marine Mammal Protection Act.

Four decades later, new research shows that the law is working.

Not only has the act "successfully prevented the extirpation of any marine mammal population in the United States in the forty years since it was enacted," write University of Vermont conservation biologist Joe Roman and his colleagues in a new report, but also, "the current status of many marine mammal populations is considerably better than in 1972."

Their study, published online on March 22, in the Annals of the New York Academy of Sciences, shows that population trends for most stocks of these animals remain unknown, but of those stocks that are known, many are increasing.

"At a very fundamental level, the MMPA has accomplished what its framers set out to do," says co-author Andrew Read, professor of marine biology at Duke University, "to protect individual marine mammals from harm as a result of human activities."

Some marine mammals, like endangered right whales, continue to be in deep trouble, but other populations "particularly seals and sea lions, have recovered to or near their carrying capacity," the scientists write.

"We have seen remarkable recoveries of some populations of marine mammals, such as gray seals in New England and sea lions and elephant seals along the Pacific coast," says Read.

"U.S. waters are pretty compromised with lots of ship traffic and ship strikes, big fisheries, pollution, boat noise, " Joe Roman says. "And yet it's safer to be a marine mammal in U.S. waters than elsewhere," he says, due to the Act's strong protections against commercial and accidental killing — what the law calls "take" — and its aim to maintain sustainable populations of mammals and their ecological roles in oceans.

"It's important to evaluate such broad legislation," says co-author Caitlin Campbell, a UVM student.

"A lot of people think that the hard part was getting it passed through Congress, but in reality you have to make sure that big protective measures like this actually are effective," she says. "This paper shows that this act is doing its job."

The research team — Campbell; Joe Roman in UVM's Gund Institute for Ecological Economics; Irit Altman from Boston University; Meagan Dunphy-Daly and Andrew Read from Duke University; and Michael Jasny from the Natural Resources Defense Council — gathered hundreds of data sets from around the world, including from NOAA, Canadian agencies, and the IUCN. Their goal was to get an accurate picture of population levels and trends of more than two hundred stocks of marine mammals from the Pantropical Spotted Dolphin to the West Indian Manatee.

The team concluded that for many of these animals there simply aren't enough data. For seventy-one percent of the stocks they identified, they couldn't say which way the population was heading, up or down. "There isn't enough research," Roman says.

But for the ones they could evaluate, they found that nineteen percent of stocks were increasing, while five percent were stable and only five percent were declining.

Another fundamental conclusion of this research: "stopping harvesting these mammals, stop fisheries bycatch, stop killing them — and many populations bounce back," says Roman. Marine mammals are long-lived "so it's going to take decades, maybe longer for populations to rebound," he says, "but it seems the trends are increasing."

In 1934, trends were definitely not increasing for right whales, when an international treaty banned hunting these nearly extinguished creatures. But other protections lagged, and by the 1960s many whales and other marine mammals — including some dolphins and seals — faced plummeting populations and the risk of extinction.

Yet in the early 1970s, the U.S. Department of Defense resisted legislation to protect whales and other marine mammals: they relied on sperm whale oil for use as a lubricant in submarines and other military engines, Roman's team writes.

In one curious part of the complex negotiations at the White House, Lee Talbot, a canny scientist working for Richard Nixon, produced an affidavit from the DuPont Corporation stating that they could produce an artificial lubricant that could do the same job as the whale oil. This helped make the Pentagon more receptive toward whale-protecting legislation. In October 1972, the Marine Mammal Protection Act passed. This victory was also a key step toward the passage of the more forceful (though less ecologically oriented) Endangered Species Act that passed the next year.

Under these two laws, "countless tens of thousands of individual whales, seals, and manatees have been protected from harm since 1972," the scientists write, "exactly as intended by those who crafted the legislation."

In 1994, major amendments to the MMPA established a new framework for dealing with interactions between marine mammals and commercial fisheries, "which remains perhaps the most important conservation issue facing these iconic animals," says Andrew Read.

This new framework, relies on "a negotiated rule-making process," Read says, looking for solutions to the incidental death of mammals in commercial fisheries. One of the strengths of the new process is that it "requires the direct involvement of fishermen, conservationists and scientists in the management process," Read says.

Still, some deeply depleted species, like right whales, may never recover, and additional threats beyond direct killing remain. The Marine Mammal Protection Act has generally been ineffective in dealing with problems like increasing underwater noise from naval operations and other ships, new diseases, and depleted prey species in fraying food webs. "Existing conservation measures have not protected large whales from fisheries interactions or ship strikes in the northwestern Atlantic," the team writes.

And this points to a new generation of challenges such as moving shipping lanes in whale feeding territory, slowing speed boats in manatee habitat, changing lobster fishing technologies and other fishing gear modifications, and continuing to improve ecosystem-based fisheries management. "That's going to be hard and require real political will," Joe Roman says.

Contact: Joshua Brown
joshua.e.brown@uvm.edu
802-656-3039
University of Vermont

 

River dolphins use lower pitch sonar signals than marine dolphins, whales

Ganges river dolphins use lower frequency biosonar clicks, but unique head anatomy may keep signals focused

Ganges river dolphin, Photo: E. & R. Mansur, WCS.

Freshwater dolphins use echolocation signals that are quieter, more low-pitched and more frequent than those used by their marine counterparts, according to research published March 27 in the open access journal PLOS ONE by Frants Havmand Jensen from Woods Hole Oceanographic Institution and colleagues.

All toothed whales use bio-sonar signals to navigate and find prey, but the echolocation signals of marine animals are better understood than those used by endangered river dolphins. In this study, the authors recorded the signals of two endangered freshwater dolphin species within the Sundarban mangrove forest, and found that they produced signals that were much quieter than signals produced by marine dolphins.

This is the cranial morphology of a Ganges river dolphin as seen from A) a left lateral and slightly anterior viewpoint, and B) an anterior viewpoint looking back along the anterior-posterior axis. Notice the unusual, highly porous bony maxillary crests that project anteriorly over the rostrum and nearly encircle the melon. Photo: Anders Galatius, Aarhus University

"Freshwater dolphins live in complex environments where circuitous river systems restrict how far away prey might be found using echolocation, especially when compared to marine dolphins echolocating in the open ocean " says Jensen.

In addition, the Ganges river dolphin produced sounds nearly an octave lower than signals of similar-sized marine dolphins. Lower-pitched sounds are likely to be less effective for echolocation, but this species has evolved unique bony crests in their foreheads that may help them focus their low-frequent biosonar signals more efficiently.

The study offers a valuable tool to help conservation biologists in their efforts to prevent a decline of these endangered species. Small acoustic recorders are being increasingly used for supplementing visual surveys, and the study describes how differences in the biosonar signals may be used to discriminate between species, estimate population sizes and identify areas crucial to the two freshwater dolphins.

This study was made possible through the logistical and field support of the Bangladesh Cetacean Diversity Project of the Wildlife Conservation Society, and funded by frame grants from the Danish Natural Science Foundation to PTM. FHJ was supported by the PhD School of Aquatic Sciences, Denmark, and is currently funded by a postdoctoral fellowship from the Danish Council for Independent Research | Natural Sciences. VMJ was supported by a fellowship of the Wissenschaftskolleg Berlin. PTM was supported by frame grants from the Danish Natural Science Foundation.

Citation: Jensen FH, Rocco A, Mansur RM, Smith BD, Janik VM, et al. (2013) Clicking in Shallow Rivers: Short-Range Echolocation of Irrawaddy and Ganges River Dolphins in a Shallow, Acoustically Complex Habitat. PLoS ONE 8(3): e59284. doi:10.1371/journal.pone.0059284

Contact: Souri Somphanith
onepress@plos.org
415-624-121-7199
Public Library of Science

 

An ancient biosonar sheds new light on the evolution of echolocation in toothed whales

Ganges River Dolphin. Photo by Rubaiyat Mansur, Whale and Dolphin Conservation Society

Some thirty million years ago, Ganges river dolphins diverged from other toothed whales, making them one of the oldest species of aquatic mammals that use echolocation, or biosonar, to navigate and find food. This also makes them ideal subjects for scientists working to understand the evolution of echolocation among toothed whales.

New research, led by Frants Havmand Jensen, a Danish Council for Independent Research | Natural Sciences postdoctoral fellow at Woods Hole Oceanographic Institution, shows that freshwater dolphins produce echolocation signals at very low sound intensities compared to marine dolphins, and that Ganges river dolphins echolocate at surprisingly low sound frequencies. The study, "Clicking in shallow rivers," was published in the journal PLOS ONE.

"Ganges River dolphins are one of the most ancient evolutionary branches of toothed whales," says Jensen. "We believe our findings help explain the differences in echolocation between freshwater and marine dolphins. Our findings imply that the sound intensity and frequency of Ganges river dolphin may have been closer to the 'starting point' from which marine dolphins gradually evolved their high-frequent, powerful biosonar."

The scientists believe these differences evolved due to differences in freshwater and marine environments and the location and distribution of prey in those environments.

A complex, underwater environment

To sustain themselves, river dolphins must find their food, often small fish or crustaceans, in highly turbid water where visibility seldom exceeds a few inches. Like their marine relatives, they manage this using echolocation: They continuously emit sound pulses into the environment and listen for the faint echoes reflected off obstacles while paying special attention to the small details in the echoes that might signify a possible meal.

The environment that freshwater dolphins operate in poses very different challenges to a biosonar than the vast expanses of the sea where most dolphins later evolved. "Dolphins that range through the open ocean often feed on patchily distributed prey, such as schools of fish," Jensen says. "They have had a large advantage from evolving an intense biosonar that would help them detect prey over long distances, but we have little idea of how the complex river habitats of freshwater dolphins shape their biosonar signals."

Shy study animals with a surprisingly deep voice

To answer that question, the researchers recorded the echolocation signals of two species of toothed whales inhabiting the same mangrove forest in the southern part of Bangladesh: The Ganges river dolphin, an exclusively riverine species that is actually not part of the dolphin family but rather the Platanistidae family, and the Irrawaddy, a freshwater toothed whale from the dolphin family that lives in both coastal and riverine habitats.

Surprisingly, the echolocation signals turned out to be much less intense than those employed by marine dolphins of similar size and it seemed that the freshwater dolphins were looking for prey at much shorter distances. From this, the researchers surmise that both the dolphin species and the river dolphin were echolocating at short range due to the complex and circuitous river system that they were foraging in.

While both Irawaddy and Ganges river dolphin produced lower intensity biosonar, the Ganges river dolphin had an unexpectedly low frequency biosonar, nearly half as high as expected if this species had been a marine dolphin.

"It is very surprising to see these animals produce such low-frequent biosonar sounds. We are talking about a small toothed whale the size of a porpoise producing sounds that would be more typical for a killer whale or a large pilot whale," says Professor Peter Teglberg Madsen from Aarhus University in Denmark, an expert on toothed whale biosonar and co-author of the study.

A new perspective on the evolution of biosonar

The study suggests that echolocation in toothed whales initially evolved as a short, broadband and low-frequent click. As dolphins and other toothed whales evolved in the open ocean, the need to detect schools of fish or other prey items quickly favored a long-distance biosonar system. As animals gradually evolved to produce and to hear higher sound frequencies, the biosonar beam became more focused and the toothed whales were able to detect prey further away.

However, the Ganges river dolphin separated from other toothed whales early throughout this evolutionary process, adapting to a life in shallow, winding river systems where a high-frequency, long-distance sonar system may have been less important than other factors such as high maneuverability or the flexible neck that helps these animals capture prey at close range or hiding within mangrove roots or similar obstructions.

Improved tools for counting animals

Freshwater dolphins are among the most endangered animal species. Only around a thousand Ganges river dolphins are thought to remain, and they inhabit some of the most polluted and overfished river systems on Earth. The results of this study will help provide local collaborators with a new tool in their struggle to conserve these highly threatened freshwater cetaceans. Using acoustic monitoring devices to identify the local species may help researchers estimate how many animals remain, and to identify what areas are most important to them.

Dr. Frants Havmand Jensen is funded by an Individual Postdoctoral Fellowship and a Sapere Aude award from the Danish Council for Independent Research | Natural Sciences. The Woods Hole Oceanographic Institution is a private, non-profit organization on Cape Cod, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the oceans and their interaction with the Earth as a whole, and to communicate a basic understanding of the oceans' role in the changing global environment. 

Dwarf whale survived well into Ice Age

Graphic showing the geologic ages of Herpetocetus and various well known marine and land mammals from California, with a life restoration of Herpetocetus. Credit: R.W. Boessenecker

Research from New Zealand's University of Otago detailing the fossil of a dwarf baleen whale from Northern California reveals that it avoided extinction far longer than previously thought.

Otago Department of Geology PhD student Robert Boessenecker has found that the fossil of the 4-5 meter long Herpetocetus, thought to be the last survivor of the primitive baleen whale family called cetotheres, may be as young as 700,000 years old.

Mr Boessenecker says the previously youngest-known fossils of this whale were from the pre-Ice Age Pliocene epoch; approximately 3 million years ago, a time before many modern marine mammals appeared. Baleen whales of this type were most common much earlier, about 10-15 million years ago.

"That this whale survived the great climatic and ecological upheavals of the Ice Age and almost into the modern era is very surprising as nearly all fossil marine mammals found after the end of the Pliocene appear identical to modern species.

"Other baleen whales underwent extreme body size increases in response to the new environment, but this dwarf whale must have still had a niche to inhabit which has only recently disappeared," he says.

The find indicates that the emergence of the modern marine mammals during the Ice Age may have happened more gradually than currently thought, he says.

The discovery also lends indirect support to a hypothesis about the modern pygmy right whale (Caperea marginata) recently published by Mr Boessenecker's colleagues Professor Ewan Fordyce and Dr Felix Marx. The pair posited that this enigmatic Southern Ocean whale is not a true right whale but actually a member of the cetothere family and one of the closest relatives of Herpetocetus.

"If their hypothesis is correct, this latest discovery indicates that other close relatives of the pygmy right whale nearly survived to modern times within the Northern Hemisphere.

"In this light, Herpetocetus can be viewed as a Northern Hemisphere equivalent of the pygmy right whale: both are small-bodied with peculiar anatomy, possibly closely related, with feeding habits that are seemingly divergent from other baleen whales."

All baleen whales lack teeth and instead use baleen to strain small prey like krill and fish from seawater. Many whales, such as humpback and blue whales, gulp enormous amounts of water during lunges, while others such as gray whales filter prey from mud on the seafloor.

Owing to a strange jaw joint, Herpetocetus could not open its mouth more than 35 degrees, unlike any modern baleen whale.

The research appears in the international journal Naturwissenschaften.

Contact: Robert Boessenecker
robert.boessenecker@otago.ac.nz
University of Otago

New study analyzes the risk to endangered whales from ships in southern California

Blue Whale and Ship. Photo: John Calambokidis/Cascadia Research

Researchers have identified areas off southern California with high numbers of whales and assessed their risk from potentially deadly collisions with commercial ship traffic in a study published in the scientific journal Conservation Biology.

Scientists from NOAA Fisheries, the Marine Mammal Commission and Cascadia Research Collective analyzed data collected over seven years by NOAA on marine mammal and ecosystem research surveys in the Southern California Bight. Maps predicting the density of endangered humpback, fin and blue whales were developed by merging the observed whale sightings with oceanographic conditions to identify the habitat preferred by the different whale species.

NOAA research vessels are used to conduct marine mammal and ecosystem surveys, as shown here. Photo: Cornelia Oedekoven NOAA, Southwest Fisheries Science Center

"We know several endangered species of whales occur in the waters off southern California," said Jessica Redfern, a NOAA Fisheries marine mammal biologist and lead author of the paper. "What we didn't know, and what this study helps provide, is an understanding of the areas with the highest numbers of whales."

Knowing where whales are more likely to be found in the ocean environment is vitally important to reduce human impacts. Although this information could be used to assess any number of human impacts, the study specifically looked at current and alternative shipping routes to and from the Ports of Los Angeles and Long Beach and the risk to humpback, fin and blue whales from ship strikes.

Researchers selected four routes to study; the shipping route in the Santa Barbara Channel, which is the current shipping route; a Central route south of the northern Channel Islands; a Central Fan route, or just the eastern part of the Central route; and a Southern route, a course south of the Central route and constrained by the protected areas around Santa Barbara, Santa Catalina, and San Nicolas Islands.

These are the routes considering in analyses of the risk to endangered whales from ships transiting to and from the Ports of Los Angeles and Long Beach. Credit: Redfern et al. 2013. Conservation Biology.

By overlaying the routes with the predicted whale densities, researchers found the route with the lowest risk for humpback whales (Southern route) had the highest risk for fin whales and vice versa. However, risk may be ameliorated for both species in one of the Central routes.

Blue whales, however, were at approximately equal risk in all routes considered because of their more even distribution throughout the study area. The authors' estimate of the number of blue whales likely killed by ships exceeds levels established by the Marine Mammal Protection Act to ensure sustainable populations. This result suggests that it is important to find ways to reduce the risk of ships striking blue whales.

"The Southern California Bight is an incredibly complex system with a diverse set of users, including the military, shipping industry and fishing industry. All users have specific needs and their input is necessary to plan the best and safest uses of these waters," said Redfern, "This paper helps to incorporate whale habitat use in the planning process so that their needs can be considered as well."

Contact: Jim Milbury
jim.milbury@noaa.gov
562-980-4006
NOAA National Marine Fisheries Service

Genetic study pursues elusive goal: How many humpbacks existed before whaling?

North Atlantic humpbacks have come back but accurate pre-whaling estimate is key to defining recovery

A humpback whale surfaces to breathe in the Atlantic Ocean off the northern coast of the Dominican Republic. Credit: Salvatore Cerchio/Wildlife Conservation Society

Scientists from Stanford University, the Wildlife Conservation Society, the American Museum of Natural History, and other organizations are closing in on the answer to an important conservation question: how many humpback whales once existed in the North Atlantic?

Building on previous genetic analyses to estimate the pre-whaling population of North Atlantic humpback whales, the research team has found that humpbacks used to exist in numbers of more than 100,000 individuals. The new, more accurate estimate is lower than previously calculated but still two to three times higher than pre-whaling estimates based on catch data from whaling records.

Known for its distinctively long pectoral fins, acrobatics, and haunting songs, the humpback whale occurs in all the world's oceans. Current estimates for humpback whale numbers are widely debated, but some have called for the level of their international protection to be dropped.

The study appears in the recently published edition of Conservation Genetics. The authors include: Kristen Ruegg and Stephen Palumbi of Stanford University; Howard C. Rosenbaum of the Wildlife Conservation Society and the American Museum of Natural History; Eric C. Anderson of the National Marine Fisheries Service and University of California-Santa Cruz; Marcia Engel of the Instituto Baleia Jubarte/Humpback Whale Institute, Brazil; Anna Rothschild of AMNH's Sackler Institute for Comparative Genomics; and C. Scott Baker of Oregon State University.

"We're certain that humpback whales in the North Atlantic have significantly recovered from commercial whaling over the past several decades of protection, but without an accurate size estimate of the pre-whaling population, the threshold of recovery remains unknown," said Dr. Kristen Ruegg of Stanford University and the lead author of the study. "We now have a solid, genetically generated estimate upon which future work on this important issue can be based."

A humpback whale calf breaches. Credit: Salvatore Cerchio/Wildlife Conservation Society

"Our current challenge is to explain the remaining discrepancy between the historical catch data and the population estimate generated by genetic analyses," said Dr. Howard Rosenbaum, study co-author and Director of the Wildlife Conservation Society's Ocean Giants Program. "The gap highlights the need for continued evaluations of whale populations, and presents new information informing the debate and challenges associated with recovery goals."

"We have spent a great deal of effort refining the techniques and approaches that give us this pre-whaling number," said Dr. Steve Palumbi of Stanford. "It's worth the trouble because genetic tools give one of the only glimpses into the past we have for whales."

Reaching some 50 feet in length, the humpback whale was hunted for centuries by commercial whaling fleets in all the world's oceans. Humpbacks had predictable migration routes and were reduced to several hundred whales in the North Atlantic. The global population was reduced by possibly 90 percent of its original size. The species received protection from the International Whaling Commission in North Atlantic waters in 1955 due to the severity of its decline.

Since that time, the humpback whales of the North Atlantic have made a remarkable comeback; experts estimate the current size of the North Atlantic's humpback whale population to be more than 17,000 animals. North Atlantic humpback whales are now one of the best-studied populations of great whales in the world and the mainstay of a multi-million dollar whale-watching industry.

But estimating the number of whales that existed prior to commercial whaling is a far more difficult problem, critical in determining when the total population has recovered. Historical catch data from the logs of whaling vessels suggest a population size between 20,000-46,000 whales, but the current genetic analysis indicates a much larger pre-whaling population. The results of the genetic analysis indicate that the North Atlantic once held between 45,000—235,000 humpback whales (with an average estimate of 112,000 animals).

A previous study using the mitochondrial DNA of humpbacks in the North Atlantic suggested a higher pre-whaling population size; an average of 240,000 individuals. To increase the accuracy of the current analysis, the team measured nine segments in the DNA sequences throughout the genome (as opposed to just one DNA segment used in the previous study).

Palumbi, who participated in the first humpback genetic analysis, added: "The International Whaling Commission reviewed the results of the first study and recommended we improve the method in six specific ways. We've done that now and have the best-ever estimate of ancient humpback populations."

Scott Baker, Associate Director of Oregon State University's Marine Mammal Institute and a co-author said: "These genetic estimates greatly improve our understanding of the genetic diversity of humpback whales, something we need to understand the impact of past hunting and to manage whales in the uncertain future."

The research team analyzed genetic samples from whales in the North Atlantic as well as the Southern Hemisphere. Southern Atlantic whales were used to answer one of the six IWC questions: was there intermixing of whale populations across the equator? The samples were analyzed by sequencing specific regions of DNA in known genes. By comparing the genetic diversity of today's population to the genetic mutation rate, Ruegg and colleagues could estimate the long-term population size of humpbacks. They also showed no substantial migration of humpbacks whales across the Equator between the Southern and Northern Atlantic, and no movement from the Pacific to the Atlantic.

The team recently used the same techniques to estimate pre-whaling numbers for the Pacific gray whale and the Antarctic minke whale. A difference of two to three times also was recorded between the genetic and catch estimates for the grey whale population, but were exactly on target for the Antarctic minke whale, which has not been extensively hunted.

This work was supported by a grant from the Lenfest Ocean Program.

Contact: John Delaney
jdelaney@wcs.org
718-220-3275
Wildlife Conservation Society