Tag Archives: whales

Humpback Whales Sing for their Supper

Whales may sing for their supper, a study in the open access journal Scientific Reports suggests.

Humpback whales (Megaptera novaeangliae) work together whilst foraging on the bottom for food – but how do they co-ordinate their behaviour? Susan Parks of Syracuse University believes she may have the answer.

Her research group have been monitoring humpback whales for a decade.

This study used digital acoustic tags to record sounds made by the whales when feeding on the bottom (at around 30-35 m depth) of the Northwest Atlantic. The data showed that whales often feed on the seafloor in close co-ordination, matching diving and behaviour on the seabed. The researchers heard the whales making a previously undescribed sound which sounded like “tick-tock”.

The scientists noticed that the bottom-feeding sounds, were only produced under low-light conditions whilst other humpback whales were nearby.

Why the whales make the noises is unclear. It may be to co-ordinate timing of feeding activities under low light conditions, to alert other humpback whales to the location of particularly good patches for feeding – acting like a dinner bell – or to flush out the prey.

“Hints of behaviour suggest that other whales who overhear the sounds are attracted to them and may eavesdrop on other whales hunting for food,” Professor Parks says.

Dinner for the humpbacks feeding on the bottom was mainly sand lance. These are eel-like fish which bury themselves in the sand of the ocean floor.

Sand Lance
Sand Lance

Humpback whales forage across habitats on a wide diversity of prey, ranging from krill to larger schooling fish species, using a variety of feeding strategies. This novel acoustic cue used whilst foraging on a bottom-dwelling prey provides yet more evidence of the learning abilities of humpback whales.

Scientific Reports is a primary research publication from the publishers of Nature.

Further Reading:
Parks, Cusano, Stimpert, Weinrich, Friedlaender & Wiley. Evidence for acoustic communication among bottom foraging humpback whales Scientific Reports 4, Article number: 7508 (2014)
Biologist reveals how whales may sing for their supper

Whale Watching from Space

But not by astronauts or space tourists. Scientists from the British Antarctic Survey are using satellite images to detect and count southern right whales (Eubalaena australis).

In recent years there have been over 420 deaths of these whales in their nursery grounds at Península Valdés in Argentina. (Out of a population last estimated at 2577 whales.) Most of the dead were calves. This number of deaths suggests that the right whale population, and its ecosystem, may be less healthy and robust than previously thought. The whales at Península Valdés comprise the largest single population and the high mortality rate has raised fresh concern for the future of the species.

Traditionally whale population size has been assessed by counting from boats, planes or shore. This is labour-intensive, costly and can be inefficient. Detection probabilities are high for ship surveys, but where surveys are carried out by small airplanes rates can be down to 40%. The researchers have tested a method of identifying whales automatically from high resolutions satellite images. They chose southern right whales to evaluate their method, as, they say “The southern right whale is an ideal subject for this work for many of the same reasons as it was an ideal whale to hunt, specifically its large size and a tendency, in the breeding season, to bask near the surface in large aggregations around sheltered coastal waters.”

The researchers – Peter T. Fretwell, Iain J. Staniland and Jaume Forcada – analysed the images manually and using image processing software.

Probable whales found by automated
Probable whales found by the automated analysis. Several of the images could be interpreted as whale pairs, or as a mother and calf, others may be displaying behaviour such as tail slapping, rolling or blowing. On several images there is a strong return at one end of the feature which is mostly likely the calluses on the whales head. Reprinted under a CC BY license with permission from British Antarctic Survey and DigitalGlobe.

Manually identified whales were put into three classes; shapes that are whale-like and whale-sized are classed as probable whales, other objects are classed as possible whales, but may include bubble slicks and some groups of seabirds. The third class are objects interpreted as sub-surface feature that are potentially whales. Their automated method found 89% of the objects manually classed as probable whales, with 23.7% false positives.

How do they know a whale-like blob is a whale? They used three criteria used to identify any objects in remotely sensed imagery:

  1. The object is the right size and shape to be a whale
  2. The object is in a place we would expect to find whales
  3. There are no (or few) other types of objects that could be misclassified as whales to cause errors of commission.

Overall the researchers were satisfied with their results and suggested that larger surveys over whole calving areas, which could potentially measure thousands of square kilometres, could be automated with a degree of success using their techniques.

Southern right whales were hunted extensively from the 17th through to the 20th century. The pre-whaling population has been estimated at 55,000–70,000 dropping to a low of just 300 animals by the 1920s.

Further Reading:
Fretwell PT, Staniland IJ, Forcada J (2014) Whales from Space: Counting Southern Right Whales by Satellite. PLoS ONE 9(2): e88655. doi:10.1371/journal.pone.0088655

Photo credit: Southern right whale (Peninsula Valdés, Patagonia, Argentina) by Michaël Catanzariti

Whale Meat Stallholders Could Face Jail in Germany

German customs officers have confiscated whale meat snacks being sold by a Norwegian stall at Berlin’s Green Week. The stallholders could face prosecution and up to a 5 year jail term.

Following a tip-off, the Whale and Dolphin Conservation Society brought the sale of the meat to the attention of the German Federal Environment Ministry. The meat is illegal in Germany and throughout most of the European Union.

“The fact that the meat of a species which is strictly protected in Germany, and the EU, is offered for sale is scandalous”, says Astrid Fuchs, campaign manager at WDC. “It is incredible that this is going on under the noses of the authorities at such a big, international exhibition.”

Green Week has been going since 1926. It is said to be the world’s biggest fair for food, agriculture and horticulture. About 1500 national and international exhibitors present typical regional products and services to over 400,000 visitors.

In 1985 the International Whaling Commission “paused” all commercial whaling. Norway and Iceland are the only countries who are members of the IWC to hunt whales commercially. Norway takes North Atlantic common minke whales and Iceland takes both North Atlantic common minke whales and North Atlantic fin whales.

Further Reading
Whale and Dolphin Conservation Society
International Whaling Commission

Photo credit: Lakkasuo (CC0 1.0)

Marine Robots detect Endangered Whales

Two submarine robots equipped with instruments designed to “listen” for the calls of baleen whales have detected nine endangered North Atlantic right whales in the Gulf of Maine.

The project employed ocean-going robots called gliders equipped with a digital acoustic monitoring (DMON) instrument and specialised software allowing the vehicle to detect and classify calls from four species of baleen whales – sei, fin, humpback and right whales. The gliders’s real-time communication capabilities alerted scientists to the presence of whales in the research area, in the first successful use of technology to report detections of several species of baleen whales from autonomous vehicles.

Using the gliders’s reconnaissance data and continued real-time updates, the science team was able to locate whales in just a few hours of searching. “We found our first right whale on the first day that we were surveying in decent weather conditions because the gliders were up there doing the leg work for us, to tell us where the animals were in real time,” says Woods Hole Oceanographic Institution (WHOI) scientist Mark Baumgartner.

The innovative whale detection system provides conservation managers with a cost-effective alternative to ship- or plane-based means of identifying the presence of whales, and gives whale ecologists new tools for understanding large animals that spend most of their lives out of human eyesight below the sea surface.

Whale researchers want to learn what draws whales to this part of the ocean during the late fall and winter. However, high winds and rough seas typical of that time of year make studying the animals very difficult.

“This presents a huge knowledge gap,” says Baumgartner.

The labor-intensive work of surveying for whales, overseen by NOAA, is usually done by human observers on ships or airplanes, and is limited by the conditions at sea.

“We’ve been doing visual based surveys for a long time – either from a plane or a boat. They have a lot of value, but they are limited, especially at certain times of the year,” says Sofie Van Parijs, leader of the Passive Acoustic Research Group at NOAA’s Northeast Fisheries Science Center (NEFSC). “These gliders provide a great complement to this system. Knowing where right whales are helps you manage interactions between an endangered species and the human activities that impact those species.”

Gliders – approximately six-foot-long, torpedo-shaped autonomous vehicles with short wings – have been in use by oceanographers for about a decade. They move up, down, and laterally in a sawtooth pattern through the water by changing their buoyancy and using their wings to provide lift. Battery powered and exceptionally quiet in the water, the gliders are equipped with an underwater microphone on the underside of the vehicle near its wings and an iridium satellite antenna on the tail section. The vehicle surfaces every few hours to get a GPS position and transmit data to shore-side computers.

The DMON – a circuit board and battery about the size of an iPhone – sits inside the glider recording audio and generating spectrograms, a form of the audio that facilitates complex sound analysis. From the spectrogram, Baumgartner’s software generates a “pitch track,” a visual representation of a whale call, and estimates which species of whale made the call based on characteristics of the pitch track. Tallies of each species’ detected calls and even a small subset of detected pitch tracks can be transmitted to shore by the vehicle. “Each pitch track takes less than 100 bytes, whereas transmitting just one of those calls as an audio clip would take about 8000 bytes of data,” says Baumgartner. This makes the system efficient and economical. And, adds Baumgartner, it’s also really flexible. It is easy to update the software to include a larger repertoire of whale calls into the software’s “call library.”

The researchers reported the presence of the whales to NOAA, the agency responsible for enforcing the Marine Mammal Protection Act. NOAA put in place a “dynamic management area”, asking mariners to voluntarily slow their vessel speed to avoid striking the animals.

Further Reading:
Woods Hole Oceanographic Institute

How Noisy were Whales before Industrial Whaling?

Concern is growing that human-generated noise in the ocean disrupts marine animals that rely on sound for communication and navigation. In the modern ocean, the background noise can be ten times louder than it was just 50 years ago. But new modeling based on recently published data suggests that 200 years ago — prior to the industrial whaling era — the ocean was even louder than today due to the various sounds whales make.

Researchers Michael Stocker and Tom Reuterdahl of Ocean Conservation Research in California, presented their findings at the 164th meeting of the Acoustical Society of America (ASA). Using historic population estimates, the researchers assigned “sound generation values” to the species for which they had good vocalization data. “In one example, 350,000 fin whales in the North Atlantic may have contributed 126 decibels – about as loud as a rock concert – to the ocean ambient sound level in the early 19th century,” Stocker notes. This noise would have been emitted at a frequency from 18 – 22 hertz.

According to the researchers, use of whaling records to determine just how many whales were harvested from the ocean over the course of industrialized whaling is difficult because the captains were taxed on their catch and therefore had an incentive to “fudge” the numbers. Some captains kept two sets of books. After the collapse of the Soviet Union, some of the real reports began surfacing. In one example the Soviets initially reported taking approximately 2,710 humpback whales from the late 1950s to the mid-1960s. The newer data reveal the actual number was closer to 48,000.

This more accurate data was supported by population estimates using mitochondrial DNA, which does not change through female lines of a species. Thus the current diversity in DNA can serve as a proxy for historic population numbers.

Their estimates suggest there was a whole lot of whale racket a couple centuries ago.

Further Reading:
Whale Racket: Sounding Out How Loud the Oceans Were From Whale Vocalizing Prior to Industrial Whaling

Lawsuit Seeks Plan for Most Endangered Large Whale in World

The Center for Biological Diversity yesterday filed a formal notice of intent to sue the National Marine Fisheries Service for failing to develop a recovery plan under the Endangered Species Act for the highly endangered North Pacific right whale. The North Pacific right whale is thought to be the most endangered large whale in the world, with as few as 30 individuals in the Bering Sea and Gulf of Alaska and perhaps a few hundred in Russia’s Okhotsk Sea.

“North Pacific right whales lead a precarious existence,” said the Center’s Alaska Director Rebecca Noblin. “Without the full protections of the Endangered Species Act, including a strong recovery plan, these whales will live on only in history books.”

Under the US Endangered Species Act, the National Marine Fisheries Service is required to issue and implement a plan for the conservation and recovery of the North Pacific right whale. Although the whale has been listed as endangered as a “northern right whale” since 1973 and since 2008 as a species in its own right, this critically endangered whale has no recovery plan.

“Recovery plans are essential to saving struggling species and helping them recover to the point where they no longer need to be listed under the Endangered Species Act,” said Noblin. “Studies have shown that species with recovery plans are far more likely to be on the road to recovery than those without.”

Right whales were so named because they were the “right whale to hunt”: they are slow swimmers, they swim within sight of shore and their carcasses float. Right whales were hunted for oil, meat, corset stays, umbrella ribs and buggy whips — until the early 20th century. Once abundant, numbering as many as 20,000 before the advent of commercial whaling, the North Pacific right whale is now the most endangered whale in the world. Today the few remaining individuals are extremely vulnerable to ship strikes, oil development and oil spills, and entanglement in fishing gear. With so few North Pacific right whales in existence, the loss of even one whale could threaten the entire population.

Though the North Pacific right whale (Eubalaena japonica) has been considered officially endangered for almost 40 years, it long shared its Endangered Species Act listing with the North Atlantic right whale (Eubalaena glacialis), thus not receiving the individual recognition and protection it deserved. But in 2008 the whales were listed as endangered as a distinct species, significantly increasing their legal protection and triggering requirements to prepare a recovery plan and take other measures for the whales’ conservation.

As compared with the intensively studied North Atlantic right whale, the more offshore and remote distribution of the North Pacific right whale may be an advantage in terms of less intensive exposure to human impacts, but the disadvantage is that impacts that do occur are less likely to be detected and their consequences are harder to ascertain and evaluate.

Further Reading:
Center for Biological Diversity
More Right Whale news stories
Reilly, S.B., Bannister, J.L., Best, P.B., Brown, M., Brownell Jr., R.L., Butterworth, D.S., Clapham, P.J., Cooke, J., Donovan, G.P., Urbán, J. & Zerbini, A.N. 2008. Eubalaena japonica. In: IUCN 2011. IUCN Red List of Threatened Species. Version 2011.2. .

Image: puttsk

Record number of whales in Antarctic Bay

Scientists have observed a “super-aggregation” of more than 300 humpback whales gorging on the largest swarm of Antarctic krill seen in more than 20 years in bays along the Western Antarctic Peninsula.

The sightings, made in waters still largely ice-free deep into austral autumn, suggest the previously little-studied bays are important late-season foraging grounds for the endangered whales. But they also highlight how rapid climate change is affecting the region.

“Such an incredibly dense aggregation of whales and krill has never been seen before in this area at this time of year,” says Douglas P. Nowacek, Repass-Rodgers University Associate Professor of Conservation Technology at Duke. Most studies have focused on whale foraging habitats located in waters farther offshore in austral summer.

Nowacek and his colleagues observed 306 humpback whales – or about 5.1 whales per square kilometer, the highest density ever recorded. They measured the krill biomass at about 2 million tons. Small, floating fragments of brash ice covered less than 10 percent of the bay.

Advancing winter sea ice used to cover much of the peninsula’s bays and fjords by May, protecting krill and forcing humpback whales to migrate elsewhere to find food, Nowacek says, but rapid climate change in the area over the last 50 years has significantly reduced the extent, and delayed the annual arrival, of the ice cover.

“The lack of sea ice is good news for the whales in the short term, providing them with all-you-can-eat feasts as the krill migrate vertically toward the bay’s surface each night. But it is bad news in the long term for both species, and for everything else in the Southern Ocean that depends on krill,” says Ari S. Friedlaender, co-principal investigator on the project and research scientist at Duke.

Antarctic krill are shrimplike creatures that feed primarily on phytoplankton and live in large swarms in the Southern Ocean. Penguins, seals, seabirds and many whale species rely on the protein-rich, pinky-sized crustaceans as a source of food. Commercial fisheries are allowed to harvest up to three-and-a-half tons of the krill a year as food for farm-raised salmon and for oil, rich in omega-3 acids, which is used in human dietary supplements.

Around the Western Antarctic Peninsula, krill migrate in austral autumn from open ocean waters to phytoplankton-rich bays and fjords, where juveniles feed and the population overwinters under the protective cover of ice. There is a strong correlation between the amount of sea ice and the amount of krill that survive the long, harsh Antarctic winter.

Further Reading:
Duke University Marine Laboratory

Several species of Killer Whale, scientist say

A study in the journal Genome Research suggests there are several species of killer whale.

It has long been thought that there are at least three types of killer whales: residents who eat fish; transients who eat mammals; and offshores about who little is known. The new research gives the strongest evidence yet supporting the theory there are several species of killer whales throughout the world’s oceans.

One of the whales suggested as a new species is the “pack ice killer whale” from the Antarctic. This has a large eye-patch and two-tone gray color pattern. This type specialises in hunting seals, which are often on the ice and need to be knocked off the ice by the whales before they can be caught.

The “Ross Sea killer whale”, also, from the Antarctic is another considered a distinct species. This has a narrow angled eye patch. It is the smallest of 3 Antarctic types and eats fish that are found under the ice pack, following them deep into the ice as it breaks up in the summer months.

A third recommended for separate species listing is the Pacific Transient killer whale. This looks similar to an Antactic open water type with the typical black and white color pattern and eye-patch, but is genetically distinct. The Transients are known to feed on all types of marine mammals, including other whales, dolphins, and seals and sea lions.

Further Reading:
Killer Whales
Genomic Analysis Indicates Mulitples Species of Killer Whale
Complete mitochondrial genome phylogeographic analysis of killer whales (Orcinus orca) indicates multiple species

Minke Whales Should Not be Culled

A new genetic analysis of Antarctic minke whales concludes that population of these smaller baleen whales have not increased as a result of the intensive hunting of other larger whales – countering arguments by advocates of commercial whaling who want to “cull” minke whales.

Antarctic minke whales are among the few species of baleen whales not decimated by commercial whaling during the 20th century, and some scientists have hypothesised that their large numbers are hampering the recovery of deleted species, such as blue, fin and humpback, which may compete for krill.

This “Krill Surplus Hypothesis” postulates that the killing of some two million whales in the Southern Ocean during the early- and mid-20th century resulted in an enormous surplus of krill, benefiting the remaining predators, including Antarctic minke whales.

But the new analysis, published this week in the journal Molecular Ecology, estimates that contemporary populations of minke whales are not “unusually abundant” in comparison with their historic numbers.

The Southern Ocean is one of the world’s largest and most productive ecosystems and in the 20th century went through what Scott Baker, a whale geneticist at Oregon State University, called “one of the most dramatic ‘experiments’ in ecosystem modification ever conducted.” The elimination of nearly all of the largest whales – such as the blue, fin and humpback – removed a huge portion of the biomass of predators in the ecosystem and changed the dynamics of predator-prey relationships.

Blue whales were reduced to about 1-2 percent of their previous numbers; fin whales to about 2-3 percent; and humpbacks to less than 5 percent. “The overall loss of large whales was staggering,” Baker said.

“It is possible that the removal of the larger whales would have meant more food for minkes,” Baker said, “but we don’t know much about the historic abundance of krill and whether the different whale species competed for it in the same places, or at the same time. It is possible that there might have been enough krill for all species prior to whaling.”

The scientists also say that current minke whale populations may be limited by other factors, including changes in sea ice cover.

“The bottom line is that the Krill Surplus Hypothesis does not appear to be valid in relation to minke whales and increasing hunting based solely on the assumption that minke whales are out-competing other large whale species would be a dubious strategy,” Baker said.

Further Reading: Oregon State University

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Albatrosses feed with Killer Whales

Scientists have recorded the first observations of how albatrosses feed alongside marine mammals at sea.

A miniature digital camera was attached to the backs of four black-browed albatrosses (Thalassarche melanophrys). Results are published online this week in the open-access journal PLoS ONE.

Albatrosses fly many hundreds of kilometers across the open ocean to find and feed upon their prey. Despite the growing number of studies concerning their foraging behaviour, relatively little is known about how albatrosses actually locate their prey. The still images recorded from the cameras showed that some albatrosses actively followed a killer whale (Orcinus orca), possibly to feed on food scraps left by this diving predator. The camera images together with the depth profiles showed that the birds dived only occasionally, but that they actively dived when other birds or the killer whale were present. This association with diving predators or other birds may partially explain how albatrosses find their prey more efficiently in the apparently ‘featureless’ ocean, with a minimal requirement for energetically costly diving or landing activities.

The camera, developed by the National Institute for Polar Research in Tokyo, is removed when the albatross returns to its breeding ground after foraging trips. It is small and weighs 82g. Although the camera slightly changes the aerodynamic shape of the albatross, it didn’t affect the breeding success of the study birds.

Dr Richard Phillips from British Antarctic Survey (BAS) says, “These images are really interesting. They show us that albatrosses associate with marine mammals in the same way as tropical seabirds often do with tuna. In both cases the prey (usually fish) are directed to the surface and then it’s easy hunting for the birds.”

The study took place at the breeding colony of black-browed albatrosses at Bird Island, South Georgia in January 2009, as part of a UK-Japan International Polar Year 2007-9 project.

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