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Fin Whale - Balaenoptera physalus
Fin Whale - Balaenoptera physalus

[Image: photo.jpg]

Scientific classification 
Kingdom: Animalia 
Phylum: Chordata 
Class: Mammalia 
Subclass: Eutheria 
Order: Cetacea 
Suborder: Mysticeti 
Family: Balaenopteridae 
Genus: Balaenoptera 
Species: Balaenoptera physalus

The fin whale (Balaenoptera physalus), also called the finback whale, razorback, or common rorqual, is a marine mammal belonging to the suborder of baleen whales. It is the second largest whale and the second largest living animal after the blue whale, growing to nearly 27 meters (88 ft) long.

Long and slender, the fin whale's body is brownish-grey with a paler underside. There are at least two distinct subspecies: the Northern fin whale of the North Atlantic, and the larger Antarctic fin whale of the Southern Ocean. It is found in all the world's major oceans, from polar to tropical waters. It is absent only from waters close to the ice pack at both the north and south poles and relatively small areas of water away from the open ocean. The highest population density occurs in temperate and cool waters. Its food consists of small schooling fish, squid, and crustaceans including mysids and krill.

Like all other large whales, the fin whale was heavily hunted during the twentieth century and is an endangered species. Almost 750,000 fin whales were taken from the Southern Hemisphere alone between 1904 and 1979 and less than 3,000 currently remain in that region. The International Whaling Commission (IWC) has issued a moratorium on commercial hunting of this whale, although Iceland and Japan have resumed hunting: in 2009, Iceland took 125 fin whales during its whaling season, and Japan took 1 fin whale in its 2008-2009 Antarctic season. The species is also hunted by Greenlanders under the Aboriginal Subsistence Whaling provisions of the IWC. Collisions with ships and noise from human activity also significantly threaten recovery.

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The fin whale has long been known to taxonomists. It was first described by Frederick Martens in 1675 and then again by Paul Dudley in 1725. These descriptions were used as the basis of the species Balaena physalus by Carl Linnaeus in 1758. The Comte de Lacepede reclassified the species as Balaenoptera physalus early in the nineteenth century. The word "physalus" comes from the Greek word physa, meaning "blows".

Fin whales are rorquals, members of the family Balaenopteridae family, which also includes the humpback whale, the blue whale, the Bryde's whale, the sei whale and the minke whale. The family diverged from the other baleen whales in the suborder Mysticeti as long ago as the middle Miocene, although it is not known when the members of these families further evolved into their own species. Hybridization between the blue whale and the fin whale is known to occur at least occasionally in the North Atlantic and in the North Pacific. Recent DNA evidence indicates that the fin whale may be more closely related to the gray whale (Eschrichtius robustus) and humpback whale (Megaptera novaeangliae), two whales in different genera, than it is to members of its own genus, such as the minke whales. If further research confirms this theory, this taxonomy would need revision.

As of 2006, there are two named subspecies, each with distinct physical features and vocalizations. 
1. Northern Fin WhaleBalaenoptera physalus physalus, inhabits the North Atlantic.
2. Antarctic Fin WhaleBalaenoptera physalus quoyi, occupies the Southern Ocean.
Most experts consider the fin whales of the North Pacific to be a third, as yet unnamed subspecies. The three groups mix at most rarely.

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Range and habitat
Fin whales may reach lengths of up to 26.8 metres (88 ft)Like many large rorquals, the fin whale is a cosmopolitan species. It is found in all the world's major oceans, and in waters ranging from the polar to the tropical. It is absent only from waters close to the ice pack at both the north and south extremities and relatively small areas of water away from the large oceans, such as the Red Sea, the Persian Gulf, the eastern part of the Mediterranean, and the Baltic Sea. The highest population density occurs in temperate and cool waters. It is less densely populated in the warmest, equatorial regions. It prefers deep waters beyond the continental shelf to shallow waters.

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Fin Whale range

The North Atlantic fin whale has an extensive distribution, occurring from the Gulf of Mexico and Mediterranean Sea, northward to the edges of the Arctic ice pack. In general, fin whales are more common north of approximately 30°N latitude, but considerable confusion arises about their occurrence south of 30°N latitude because of the difficulty in distinguishing fin whales from Bryde's whales. Extensive ship surveys have led researchers to conclude that the summer feeding range of fin whales in the western North Atlantic was mainly between 41°20'N and 51°00'N, from shore seaward to the 1,000 fathoms (1,800 m) contour.

Summer distribution of fin whales in the North Pacific is the immediate offshore waters from central Baja California to Japan, and as far north as the Chukchi Sea bordering the Arctic Ocean. They occur in high densities in the northern Gulf of Alaska and southeastern Bering Sea between May and October, with some movement through the Aleutian passes into and out of the Bering Sea. Several whales tagged between November and January off southern California were killed in the summer off central California, Oregon, British Columbia, and in the Gulf of Alaska. Fin whales have been observed feeding in Hawaiian waters in mid-May, and several winter sightings have been made there. Some researchers have suggested that the whales migrate into Hawaiian waters primarily in the autumn and winter.

Although fin whales are certainly migratory, moving seasonally in and out of high-latitude feeding areas, the overall migration pattern is not well understood. Acoustic readings from passive-listening hydrophone arrays indicate a southward migration of the North Atlantic fin whale occurs in the autumn from the Labrador-Newfoundland region, south past Bermuda, and into the West Indies. One or more populations of fin whales are thought to remain year-round in high latitudes, moving offshore, but not southward in late autumn. In the Pacific, migration patterns are poorly characterized. Although some fin whales are apparently present year-round in the Gulf of California, there is a significant increase in their numbers in the winter and spring. Antarctic fin whales migrate seasonally from relatively high-latitude Antarctic feeding grounds in the summer to low-latitude breeding and calving areas in the winter. The location of winter breeding areas is still unknown, since these whales tend to migrate in the open ocean.

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Description and behavior
The fin whale is usually distinguished by its great length and slender build. The average size of males and females is 19 and 20 meters (62 and 66 ft), respectively. Subspecies in the Northern Hemisphere are known to reach lengths of up to 24 metres (79 ft) and the Antarctic subspecies reaches lengths of up to 26.8 metres (88 ft). A full-sized adult has never been weighed, but calculations suggest that a 25 metres (82 ft) animal could weigh as much as 70,000 kilograms (150,000 lb). Full physical maturity is attained between 25 and 30 years. Fin whales live to 94 years of age. A newborn fin whale measures about 6.5 metres (21 ft) in length and weighs approximately 1,800 kilograms (4,000 lb).[18] The animal's large size aids in identification, and it is usually only confused with the blue whale, the sei whale, or, in warmer waters, Bryde's whale.

The fin whale has a brownish grey top and sides and a whitish underside. It has a pointed snout, paired blowholes, and a broad, flat rostrum. Two lighter-colored chevrons begin midline behind the blowholes and slant down the sides toward the tail on a diagonal upward to the dorsal fin, sometimes recurving forward on the back. It has a large white patch on the right side of the lower jaw, while the left side of the jaw is grey or black. This type of asymmetry can be seen occasionally in minke whales, but the fin whale's asymmetry is universal and thus is unique among cetaceans and is one of the keys to making a full identification. It was hypothesized to have evolved because the whale swims on its right side when surface lunging and it often circles to the right while at the surface above a prey patch. However, the whales just as often circle to the left. There is no accepted hypothesis to explain the asymmetry.

The whale has a series of 56–100 pleats or grooves along the bottom of the body that run from the tip of the chin to the navel that allow the throat area to expand greatly during feeding. It has a curved, prominent 60 centimetres (24 in)dorsal fin about three-quarters of the way along the back. Its flippers are small and tapered, and its tail is wide, pointed at the tip, and notched in the center.

When the whale surfaces, the dorsal fin is visible soon after the spout. The spout is vertical and narrow and can reach heights of 6 metres (20 ft). The whale will blow one to several times on each visit to the surface, staying close to the surface for about one and a half minutes each time. The tail remains submerged during the surfacing sequence. It then dives to depths of up to 250 metres (820 ft) each dive lasting between 10 and 15 minutes. Fin whales have been known to leap completely out of the water.

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Life history
Mating occurs in temperate, low-latitude seas during the winter, followed by an eleven months to one year gestation period. A newborn weans from its mother at 6 or 7 months of age when it is 11 or 12 metres (39 ft) in length, and the calf follows the mother to the winter feeding ground. Females reproduce every 2 to 3 years, with as many as 6 fetuses being reported, but single births are far more common. Females reach sexual maturity at between 3 and 12 years of age.

The fin whale is a filter-feeder, feeding on small schooling fish, squid, and crustaceans including mysids and krill. It feeds by opening its jaws while swimming at a relatively high speed, 11 kilometres per hour (6.8 mph) in one study, which causes it to engulf up to 70 cubic metres (18,000 US gal; 15,000 imp gal) of water in one gulp. It then closes its jaws and pushes the water back out of its mouth through its baleen, which allows the water to leave while trapping the prey. An adult has between 262 and 473 baleen plates on each side of the mouth. Each plate is made of keratin that frays out into fine hairs on the ends inside the mouth near the tongue. Each plate can measure up to 76 centimetres (30 in) in length and 30 centimetres (12 in) in width. The whale routinely dives to depths of more than 200 metres (660 ft) where it executes an average of four "lunges", where it feeds on aggregations of krill. Each gulp provides the whale with approximately 10 kilograms (22 lb) of krill. One whale can consume up to 1,800 kilograms (4,000 lb) of food a day, leading scientists to conclude that the whale spends about three hours a day feeding to meet its energy requirements, roughly the same as humans. If prey patches are not sufficiently dense, or are located too deep in the water, the whale has to spend a larger portion of its day searching for food. One hunting technique is to circle schools of fish at high speed, frightening the fish into a tight ball, then turning on its side before engulfing the massed prey.

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The fin whale is one of the fastest cetaceans and can sustain speeds of 37 kilometres per hour (23 mph) and bursts in excess of 40 kilometres per hour (25 mph)have been recorded, earning the fin whale the nickname "the greyhound of the deep". Fin whales are more gregarious than other rorquals, and often live in groups of 6–10, although feeding groups may reach up to 100 animals.

Like other whales, the male fin whale makes long, loud, low-frequency sounds. The vocalizations of blue and fin whales are the lowest-frequency sounds made by any animal. Most sounds are frequency-modulated (FM) down-swept infrasonic pulses from 16 to 40 hertz frequency (the range of sounds that most humans can hear falls between 20 hertz and 20 kilohertz). Each sound lasts one to two seconds, and various sound combinations occur in patterned sequences lasting 7 to 15 minutes each. The whale then repeat the sequences in bouts lasting up to many days. The vocal sequences have source levels of up to 184–186 decibels relative to 1 micropascal at a reference distance of one meter, and can be detected hundreds of miles from their source.

When fin whale sounds were first recorded by US biologists, they did not realize that these unusually loud, long, pure and regular sounds were being made by whales. They first investigated the possibilities that the sounds were due to equipment malfunction, geophysical phenomena, or even part of a Soviet Union scheme for detecting enemy submarines. Eventually, biologists demonstrated that the sounds were the vocalizations of fin whales.

Direct association of these vocalizations with the reproductive season for the species and that only males make the sounds point to these vocalizations as possible reproductive displays. Over the past 100 years, the dramatic increase in ocean noise from shipping and naval activity may have slowed the recovery of the fin whale population, by impeding communications between males and sexually receptive females.

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Population and trends
Poor understanding of migration patterns combined with contradictory population surveys makes estimating the historical and current population levels of the whale difficult and contentious. Due to a long history of hunting this whale, pre-exploitation population levels are difficult to determine.

[blockquote]North Atlantic
North Atlantic fin whales are defined by the International Whaling Commission to exist in one of seven discrete population zones: Nova Scotia-New England, Newfoundland-Labrador, western Greenland, eastern Greenland-Iceland, North Norway, West Norway-Faroe Islands, and Ireland-Spain-United Kingdom-Portugal. Results of mark-and-recapture surveys have indicated that some movement occurs across the boundaries of these population zones, suggesting that each zone is not entirely discrete and that some immigration and emigration does occur. J. Sigurjónsson estimated in 1995 that total pre-exploitation population size in the entire North Atlantic ranged between 50,000 and 100,000 animals, but his research is criticized for not providing supporting data and an explanation of his reasoning. In 1977, D.E. Sergeant suggested a "primeval" aggregate total of 30,000 to 50,000 throughout the North Atlantic. Of that number, about 8,000 to 9,000 would have resided in the Newfoundland and Nova Scotia areas, with whales summering in U.S. waters south of Nova Scotia presumably omitted. J.M. Breiwick estimated that the "exploitable" (above the legal size limit of ft50) component of the Nova Scotia population was 1,500 to 1,600 animals in 1964, reduced to only about 325 in 1973. Two aerial surveys in Canadian waters since the early 1970s gave numbers of 79 to 926 whales on the eastern Newfoundland-Labrador shelf in August 1980, and a few hundred in the northern and central Gulf of Saint Lawrence in August 1995–1996. Summer estimates in the waters off western Greenland range between 500 and 2,000, and in 1974, Jonsgard considered the fin whales off Western Norway and the Faroe Islands to "have been considerably depleted in postwar years, probably by overexploitation". The population around Iceland appears to have fared much better, and in 1981, the population appeared to have undergone only a minor decline since the early 1960s. Surveys during the summers of 1987 and 1989 estimated of 10,000 to 11,000 between eastern Greenland and Norway. This shows a substantial recovery when compared to a survey in 1976 showing an estimate of 6,900, which was considered to be a "slight" decline since 1948. Summer population estimates in the British Isles-Spain-Portugal area range from 7,500 to more than 17,000. The aggregate population level is estimated to be between 40,000 and 56,000 individuals.

North Pacific
The total historical North Pacific population was estimated at 42,000 to 45,000 before the start of whaling. Of this, the population in the eastern portion of the North Pacific was estimated to be 25,000 to 27,000. By 1975, the estimate had declined to between 8,000 and 16,000. Surveys conducted in 1991, 1993, 1996, and 2001 produced estimates of between 1,600 and 3,200 off California and 280 to 380 off Oregon and Washington. The miniumum estimate for the California-Oregon-Washington population, as defined in the U.S. Pacific Marine Mammal Stock Assessments: 2005, is about 2,500. Surveys in coastal waters of British Columbia in summers 2004 and 2005 produced abundance estimates of approximately 500 animals (95% confidence intervals: 201-1,220). Surveys near the Pribilof Islands in the Bering Sea indicated a substantial increase in the local abundance of Fin Whales between 1975–1978 and 1987–1989. In 1984, the entire population was estimated to be at less than 38% of its historic carrying capacity.

Relatively little is known about the historical and current population levels of the Antarctic fin whale. The IWC officially estimates that the Southern Hemisphere pre-whaling population was 400,000 whales, and that the population in 1979 (at the cessation of Antarctic large scale whaling) was 85,200. Both the current and historical estimates should be considered as poor estimates because the methodology and data used in the study are known to be flawed. Other estimates cite current (late 1980s-early 1990s) population levels of no more than 5,000 whales and possibly as low as 2,000 to 3,000.[/blockquote]

As of 2006, there is no scientifically accepted estimate of current population or trends in abundance.

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Human interaction
In the 19th century, the fin whale was occasionally hunted by open-boat whalers, but it was relatively safe because of its speed and the fact that it often sank when killed. However, the later introduction of steam-powered boats and harpoons that exploded on impact made it possible to kill and secure them along with blue whales and sei whales on an industrial scale. As other whale species became over-hunted, the whaling industry turned to the still-abundant fin whale as a substitute. It was primarily hunted for its blubber, oil, and baleen. Approximately 704,000 fin whales were caught in Antarctic whaling operations alone between 1904 and 1975.

The introduction of factory ships with stern slipways in 1925 substantially increased the number of whales taken per year. In 1937 alone, over 28,000 fin whales were taken. From 1953 to 1961, the catch averaged around 25,000 per year. By 1962, sei whale catches began to increase as fin whales became scarce. By 1974, fewer than 1,000 fin whales were being caught each year. In the North Pacific, a reported total of approximately 46,000 fin whales were killed by commercial whalers between 1947 and 1987.

The IWC prohibited hunting in the southern hemisphere in 1976. The Soviet Union engaged in the illegal killing of protected whale species in the North Pacific, rendering reported catch data incomplete. The fin whale was given full protection from commercial whaling by the IWC in the North Pacific in 1976, and in the North Atlantic in 1987, with small exceptions for aboriginal catches and catches for research purposes. All populations worldwide remain listed as endangered species by the US National Marine Fisheries Service and the International Conservation Union Red List, and the fin whale is on Appendix 1 of CITES.

The IWC has set a quota of 19 fin whales per year for Greenland. Meat and other products from whales killed in these hunts are widely marketed within Greenland, but export is illegal. Iceland and Norway are not bound by the IWC's moratorium on commercial whaling because both countries filed objections to the moratorium. In October 2006, Iceland's fisheries ministry authorized the hunting of nine fin whales through August 2007.

In the southern hemisphere, Japan permits annual takes of 10 fin whales under its Antarctic Special Permit whaling program for the 2005–2006 and 2006–2007 seasons. The proposal for 2007–2008 and the subsequent 12 seasons allows taking 50 per year, but by the close of the 2007-2008 season in April 2008, no fin whales had been caught.

Collisions with ships are a major cause of mortality. In some areas, they cause a substantial portion of large whale strandings. Most serious injuries are caused by large, fast-moving ships over or near the continental shelf.

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Secret of Whale's Open-Mouth Feeding Tactic Revealed

By Clara Moskowitz, LiveScience Senior Writer
posted: 23 July 2010 11:34 am ET

To catch a meal, humpback whales dive at high speeds with mouths open to engulf large volumes of water filled with prey. Now scientists have detected the unique bone adaptations that allow the whales to do this without being injured by the torrents of water and pressure they face. 

The study involved rorqual whales, a family of species that includes humpback whales and blue whales – the largest animals on Earth. These creatures feed on small fish and shrimp-like krill by sucking in water during dives deep into the ocean – a practice called lunge feeding. 

The whales have a special stretchy tissue attached to their jaws called ventral groove blubber. When they lower their jaws to extreme angles and swim very quickly, a drag force on this blubber causes it to expand to encompass a volume that can be bigger than the whale itself. This enables rorqual whales to capture enough food in a few hours to sustain them for the rest of the day. 

Yet this feeding takes a toll. The extreme force of the inrushing water pulls on the blubber, which exerts an extremely strong drag on a whale's lower jaw – called a mandible. Scientists have been unsure how the mandible can actually withstand such force. 

"We were interested in finding out whether the mandibles exhibit a specialized mechanical design that would enable to them to not break during the stresses," said zoology student Daniel J. Field of the University of British Columbia in Vancouver, Canada. "The fact that they can withstand such gigantic forces is truly remarkable." 

For his undergraduate thesis, Field worked with his supervisor Robert Shadwick and fellow researchers to measure the mandible bones of humpback whales. The team used a process of X-ray scanning called quantitative computed tomography (QCT) to calculate the jaw bones' three-dimensional geometry and density distribution. 

The scientists discovered that humpback whale mandibles are shaped in a unique way, different from the mandibles of humans and right whales – the only other species for which QCT data is available. 

In particular, the scientists measured a feature called flexural rigidity – a combination of high bone density and large cross-sectional area that allows a bone to resist bending. The researchers found that humpback whales' jaws are formed with a unique pattern of flexural rigidity – highest at the edges attached to the skull, and lowest at the center – that is optimized to resist the strain from lunge feeding. 

"Just by having a look at the data it's really surprising how beautifully adapted the whales' mandibles are to withstand the forces it's exposed to on a daily basis," Field told LiveScience. "It was surprising and quite interesting to discover." 

The researchers published their findings in the July 2010 issue of the journal The Anatomical Record: Advances in Integrative Anatomy and Evolutionary Biology. 

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Humpback whales lunge feed to catch huge volumes of prey-filled water in their engorged mouths. 
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'Tanned' whales' sun response gives clues to human ageing

By Matt McGrath
Environment correspondent, BBC News

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A blue whale’s head and tail fluke tend to be uniformly grey but their dorsal skin is usually mottled and can be quite pale.

The way that whales react to sunlight can shed new light on the human ageing process, say researchers.

Some species react by getting darker with UV exposure in the same way as humans get a tan.

Others though, protect from themselves from sun burn by turning genes on and off.

The work, which is published in the journal Scientific Reports, could lead to new anti-ageing treatments in humans.

For several years now, marine biologists in Mexico have noticed an increasing number of whales in the region with blistered skin as a result of exposure to UV light.

Over a three-year period researchers took skin samples from three different species of whales during their annual spring migration, when they move to the sunnier waters of the Gulf of California.

Warmer Blue

The scientists found the different species reacted differently to the increase in sunlight.

Blue whales are the biggest creatures ever to have lived on Earth, and they respond to the Sun by increasing the amount of pigment in their skin, just like humans.

"When blue whales go on their holidays to the Gulf of California they get a tan the same way we do," Prof Mark Birch-Machin from Newcastle University told BBC News.

"And that tan protects blue whales from sunburnt DNA."

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The scientists used crossbows and modified arrows to take skin biopsies from blue whales in the Gulf of California

According to Prof Birch-Machin, exposure to ultra violet light can damage not just skin but can harm DNA in mitochondria, the battery packs of cells.

The ability of blue whales to tan in response to UV exposure may be connected to their historic migratory patterns as they move annually from higher to lower latitudes with a greater amount of sunlight.

Sperm whales have a different approach to the sun, says Prof Birch-Machin. They can spend up to six hours at a time on the surface of the ocean and have far greater exposure to UV light.

"They are akin to people going for the lobster approach - so changes in pigment aren't going to help them very much as the UV is overwhelming the system," he said.

Instead of changes in their pigment, the sun triggers a stress response in the genes of these whales, which is similar to our own protective mechanism against sun damage.

"We saw for the first time evidence of genotoxic pathways being activated in the cells of the whales," said researcher Amy Bowman.

"This is similar to the damage response caused by free radicals in human skin which is our protective mechanism against sun damage," she added.

Fins getting better

The third species the scientists examined were fin whales. These deeply pigmented animals were found to be more resistant to sun damage, with the lowest prevalence of sunburn lesions.

The researchers hope that by seeing both changes in pigment and changes in genes, the whales may shed some light on the ageing process in humans.

"The sunburnt DNA we find in whales is the same sunburnt DNA we find in humans and that is definitely linked to ageing," said Prof Birch-Machin.

"The study shows the interaction of systems that we can then examine further in human research, and that's got implications for anti-ageing and skin cancer approaches," he said.

And the research, he believes, will be of interest to pharmaceutical companies.

"They are always on the lookout for what they can see in non-human systems and what they can borrow from that in terms of anti-ageing and this research will certainly help in that," he said.

The scientists say that further work is required to see if the sun burn that the whales are experiencing turns into skin cancer. They also want to know if an early warning system for the animals can be developed.

Whales Use Distinct Strategies to Counteract Solar Ultraviolet Radiation

Laura M. Martinez-Levasseur, Mark A. Birch-Machin, Amy Bowman, Diane Gendron, Elizabeth Weatherhead, Robert J. Knell & Karina Acevedo-Whitehouse

Scientific Reports 3, Article number: 2386 doi:10.1038/srep02386
Received 04 June 2013 Accepted 23 July 2013 Published 30 August 2013

A current threat to the marine ecosystem is the high level of solar ultraviolet radiation (UV). Large whales have recently been shown to suffer sun-induced skin damage from continuous UV exposure. Genotoxic consequences of such exposure remain unknown for these long-lived marine species, as does their capacity to counteract UV-induced insults. We show that UV exposure induces mitochondrial DNA damage in the skin of seasonally sympatric fin, sperm, and blue whales and that this damage accumulates with age. However, counteractive molecular mechanisms are markedly different between species. For example, sperm whales, a species that remains for long periods at the sea surface, activate genotoxic stress pathways in response to UV exposure whereas the paler blue whale relies on increased pigmentation as the season progresses. Our study also shows that whales can modulate their responses to fluctuating levels of UV, and that different evolutionary constraints may have shaped their response strategies.

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A) Photograph showing, from top to bottom, a blue whale (pale grey skin colour, the lightest species), a sperm whale (dark grey skin colour) and a fin whale (black skin colour, the darkest species). This photograph was taken by DG. (B) Differences in density of melanocytes (thick bars) and melanin (thin bars) amongst the three studied species (n = 53, n = 17, n = 45 for blue, sperm and fin whales respectively). © Association between melanin abundance and melanocyte counts in whales. Grey dots correspond to blue whales, black dots to fin whales and crosses to sperm whales. The counting area was determined as previously described. Briefly, the number of melanocytes per 100 arbitrary units was determined in triplicate along the entire epidermal ridge. The number of epidermal ridges to count was established a priori based on a cumulative curve. 
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Baleen whales hear through their bones

Date: January 29, 2015
Source: San Diego State University
Understanding how baleen whales hear has posed a great mystery to marine mammal researchers. Biologists reveal that the skulls of at least some baleen whales, specifically fin whales in their study, have acoustic properties that capture the energy of low frequencies and direct it to their ear bones.

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The fin whale skull used for this study now resides in SDSU's Museum of Biodiversity.

Understanding how baleen whales hear has posed a great mystery to marine mammal researchers. New research by San Diego State University biologist Ted W. Cranford and University of California, San Diego engineer Petr Krysl reveals that the skulls of at least some baleen whales, specifically fin whales in their study, have acoustic properties that capture the energy of low frequencies and direct it to their ear bones.
Baleen whales, also known as mysticetes, are the largest animals on earth, and include blue whales, minke whales, right whales, gray whales and fin whales. These whales can emit extremely low frequency vocalizations that travel extraordinary distances underwater. The wavelengths of these calls can be longer than the bodies of the whales themselves.
All of these whales are considered endangered, with the exception of the gray whale, which recently was removed from the endangered species list, Cranford said.
Over the past few years, government regulators have been attempting to enact laws placing limits on the amount of human-made noise that baleen whales can be exposed to. These human-made noises come primarily from three sources: commercial shipping, energy exploration, and military exercises.
According to Cranford, baleen whales might be particularly susceptible to negative effects from these sounds. Many of them produce vocalizations in the same frequency range as human-made noises, and too much human-made noise could limit the distance over which the whales are able to communicate about things like food and mates. Because low frequency sounds travel so far in the ocean, groups of whales that appear to be extremely far apart might indeed be within "hollerin' distance," as Cranford puts it.
However, little information was available about how baleen whales actually hear for government regulators to base new legislation on. Most of what scientists know about how whales hear comes from inferring their frequency range from their own vocalizations, as well as anatomic studies of the ears and some sound playback experiments with whales in controlled environments. Cranford and Krysl wanted to take a different approach: build a highly complex three-dimensional computer model of a baleen whale head--including the skin, skull, eyes, ears, tongue, brain, muscles, and jaws--and then simulate how sound would travel through it.
In 2003, they got their opportunity when a young fin whale beached on Sunset Beach in Orange County, California. Despite intensive efforts to save the whale, it died. Cranford and Krysl were able to obtain the animal's head for their research, placing it in an X-ray CT scanner originally designed for rocket motors.
Once they had their scan, the researchers employed a technique known as finite element modeling that breaks up data representing the skull and other parts of the head into millions of tiny elements and tracks their relationships with one another.
It's a bit like dividing the whale's head into a series of LEGO bricks, Cranford explained, where the properties of the bone, muscle, and other materials determine how strong the connections are between the bricks. By simulating a sound wave passing through their computerized skull, they could see how each miniscule component of bone vibrates in response.
"At that point, computationally, it's just a simple physics problem," Cranford explained. "But it's one that needs lots and lots of computational power. It can swamp most computers."
There are two ways sound can reach a whale's tympanoperiotic complex (TPC), an "interlocking bony puzzle" of ear bones that is rigidly attached to the skull. One way is for the sound's pressure waves to travel through the whale's soft tissue to their TPC, but this becomes ineffective once sound waves are longer than the whale's body, Cranford said.
The second way is for sounds to vibrate along the skull, a process known as bone conduction. Unlike pressure waves passing through soft tissue, longer waves lengths are amplified as they vibrate the skull.
When Cranford and Krysl modeled various wavelengths traveling through their computerized skull, they found that bone conduction was approximately four times more sensitive to low frequency sounds than the pressure mechanism. Importantly, their model predicts that for the lowest frequencies used by fin whales, 10 Hz -- 130 Hz, bone conduction is up to 10 times more sensitive.
"Bone conduction is likely the predominant mechanism for hearing in fin whales and other baleen whales," Cranford said. "This is, in my opinion, a grand discovery."
Krysl added that we humans experience a version of this phenomenon, too.
"We have that experience when we submerge entirely in a pool," he said. "Our ears are useless, but we still hear something because our head shakes under the pushing and pulling of the sound waves carried by the water."
The researchers published their results today in the journal PLOS ONE. The fin whale skull used for their experiment now resides in SDSU's Museum of Biodiversity.
It's possible these new findings will help legislators decide on limits to oceanic human-made noise, but Cranford stressed that what's most important about their project is that they managed to solve a long-standing mystery about a highly inaccessible animal.
"What our contribution does is give us a window into how the world's largest animals hear, by an odd mechanism no less," he said. "This research has driven home one beautiful principle: Anatomic structure is no accident. It is functional, and often beautifully designed in unanticipated ways."
Cranford and Krysl have studied many species of toothed whales and beaked whales over the past 13 years, as well as dolphins and fish. Their next step is to try to replicate the study for other species of baleen whales. The researchers will be reaching out to museums that house whale skulls.
"There is a blueprint for multiple species and it is useful to compare across species to gain insight," Krysl explained.

Journal Reference:
Ted W. Cranford, Petr Krysl. Fin Whale Sound Reception Mechanisms: Skull Vibration Enables Low-Frequency Hearing. PLOS ONE, 2015; 10 (1): e0116222 DOI: 10.1371/journal.pone.0116222

Hearing mechanisms in baleen whales (Mysticeti) are essentially unknown but their vocalization frequencies overlap with anthropogenic sound sources. Synthetic audiograms were generated for a fin whale by applying finite element modeling tools to X-ray computed tomography (CT) scans. We CT scanned the head of a small fin whale (Balaenoptera physalus) in a scanner designed for solid-fuel rocket motors. Our computer (finite element) modeling toolkit allowed us to visualize what occurs when sounds interact with the anatomic geometry of the whale’s head. Simulations reveal two mechanisms that excite both bony ear complexes, (1) the skull-vibration enabled bone conduction mechanism and (2) a pressure mechanism transmitted through soft tissues. Bone conduction is the predominant mechanism. The mass density of the bony ear complexes and their firmly embedded attachments to the skull are universal across the Mysticeti, suggesting that sound reception mechanisms are similar in all baleen whales. Interactions between incident sound waves and the skull cause deformations that induce motion in each bony ear complex, resulting in best hearing sensitivity for low-frequency sounds. This predominant low-frequency sensitivity has significant implications for assessing mysticete exposure levels to anthropogenic sounds. The din of man-made ocean noise has increased steadily over the past half century. Our results provide valuable data for U.S. regulatory agencies and concerned large-scale industrial users of the ocean environment. This study transforms our understanding of baleen whale hearing and provides a means to predict auditory sensitivity across a broad spectrum of sound frequencies. 
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Gigantic whales have stretchy 'bungee cord' nerves

Date: May 4, 2015
Source: University of British Columbia
Biologists have discovered a unique nerve structure in the mouth and tongue of rorqual whales that can double in length and then recoil like a bungee cord. The stretchy nerves explain how the massive whales are able to balloon an immense pocket between their body wall and overlying blubber to capture prey during feeding dives.

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Expansion of the ventral grooved blubber during a fin whale lunge is shown.

University of British Columbia (UBC) researchers have discovered a unique nerve structure in the mouth and tongue of rorqual whales that can double in length and then recoil like a bungee cord.

The stretchy nerves explain how the massive whales are able to balloon an immense pocket between their body wall and overlying blubber to capture prey during feeding dives.

"This discovery was totally unexpected and unlike other nerve structures we've seen in vertebrates, which are of a more fixed length," says Wayne Vogl of UBC's Cellular and Physiological Sciences department.

"The rorquals' bulk feeding mechanism required major changes in anatomy of the tongue and mouth blubber to allow large deformation, and now we recognize that it also required major modifications in the nerves in these tissues so they could also withstand the deformation."

In humans, stretching nerves usually damages them. In these whales, the nerve cells are packaged inside a central core in such a way that the individual nerve fibers are never really stretched, they simply unfold.

"Our next step is to get a better understanding of how the nerve core is folded to allow its rapid unpacking and re-packing during the feeding process," says UBC zoologist Robert Shadwick.

The researchers don't know yet whether anything similar will turn up in other animals -- the ballooning throats of frogs, for example, or the long and fast tongues of chameleons.

"This discovery underscores how little we know about even the basic anatomy of the largest animals alive in the oceans today," says Nick Pyenson, a UBC postdoctoral fellow currently curator of fossil marine mammals at the Smithsonian's National Museum of Natural History. "Our findings add to the growing list of evolutionary solutions that whales evolved in response to new challenges faced in marine environments over millions of years."

The findings are reported in Current Biology. Rorquals are the largest group among baleen whales, and include blue whales and fin whales. Specimens the researchers studied were obtained at a commercial whaling station in Iceland.

Journal Reference:
A. Wayne Vogl, Margo A. Lillie, Marina A. Piscitelli, Jeremy A. Goldbogen, Nicholas D. Pyenson, Robert E. Shadwick. Stretchy nerves are an essential component of the extreme feeding mechanism of rorqual whales. Current Biology, 2015; 25 (9): R360 DOI: 10.1016/j.cub.2015.03.007

Rorqual whales (Balaenopteridae) are among the largest vertebrates that have ever lived and include blue (Balaenoptera musculus) and fin (Balaenoptera physalus) whales. Rorquals differ from other baleen whales (Mysticeti) in possessing longitudinal furrows or grooves in the ventral skin that extend from the mouth to the umbilicus. This ventral grooved blubber directly relates to their intermittent lunge feeding strategy, which is unique among vertebrates and was potentially an evolutionary innovation that led to gigantism in this lineage. This strategy involves the rorqual whale rapidly engulfing a huge volume of prey-laden water and then concentrating the prey by more slowly expelling the water through baleen plates ( Figure 1 A). The volume of water engulfed during a lunge can exceed the volume of the whale itself. During engulfment, the whale accelerates, opens its jaw until it is almost perpendicular to the rostrum, and then the highly compliant floor of the oral cavity is inflated by the incoming water. The floor of the oral cavity expands by inversion of the tongue and ballooning of the adjacent floor of the mouth into the cavum ventrale, an immense fascial pocket between the body wall and overlying blubber layer that reaches as far back as the umbilicus. The ventral grooved blubber in fin whales expands by an estimated 162% in the circumferential direction and 38% longitudinally. In fin whales, multiple lunges can occur during a single dive, and the average time between lunges is just over forty seconds. Here, we show that nerves in the floor of the oral cavity of fin whales are highly extensible. 
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Alaska researcher investigates multiple endangered fin whale deaths
Nine whales appear to have died at the same time, area

Date: June 19, 2015
Source: University of Alaska Fairbanks
At least nine fin whales have been discovered floating dead in waters from Kodiak to Unimak Pass since late May. 'It is an unusual and mysterious event that appears to have happened around Memorial Day weekend,' said a marine mammal specialist. 'We rarely see more than one fin whale carcass every couple of years.'

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The first of several dead fin whales, later named FW01, floats outside Marmot Bay on May 23.

At least nine fin whales have been discovered floating dead in waters from Kodiak to Unimak Pass since late May.

'It is an unusual and mysterious event that appears to have happened around Memorial Day weekend,' said Kate Wynne, an Alaska Sea Grant marine mammal specialist and University of Alaska Fairbanks professor. 'We rarely see more than one fin whale carcass every couple of years.'

On May 23, Wynne received a message from National Oceanic and Atmospheric Administration enforcement officers that crew members on the Alaska Marine Highway System's ferry MV Kennicott had photographed dead whales. During the next two weeks, boaters, fishermen and pilots reported floating dead whales in the area. Based on photos submitted with these reports, Wynne and her NOAA collaborators determined that at least nine fin whales died in a relatively small area. The dead whales are now drifting along both sides of Kodiak Island.

'It is really perplexing for a number of reasons,' Wynne said. 'They appear to have all died around the same time. And the strange thing is they are all one species, with the exception of one dead humpback whale found in a different location.'

'So part of the mystery is why just fin whales? Why not their prey? Why are there not other consumers in the system showing up in mass die-off mode?' said Wynne.

Fin whales, an endangered species, grow to 70 feet long. They use baleen in their mouths to strain copepods, krill and small fish from seawater. The whales feed in tight formations, so Wynne thinks the dead whales could have consumed something toxic around the week of May 20.

Only two carcasses have come ashore. Wynne and fellow marine mammal specialist Bree Witteveen were able to take samples from one. The whale had been dead and floating in the water for a week. Samples were sent to a lab for biotoxin analysis.

Wynne has been working with NOAA's marine mammal stranding network in Juneau and with Kodiak residents.

'There is a network of interagency people working together to collect as much information as possible on the whales,' she said. 'We are asking people to watch for, report and photograph dead birds, fish or anything that seems unusual to determine if it is related to the dead whales.'

'In the meantime we are mapping and tracking reported whale carcasses, collecting water samples to look for harmful algal blooms and recording changes in sea water temperature,' she said. 'So far there is no 'smoking gun' in this environmental mystery.'

Story Source: University of Alaska Fairbanks. "Alaska researcher investigates multiple endangered fin whale deaths: Nine whales appear to have died at the same time, area." ScienceDaily. ScienceDaily, 19 June 2015. <>. 
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Blue and fin whale distribution in waters off Southern California

Date: June 25, 2015
Source: University of California - San Diego
A new study indicates a steady population trend for blue whales and an upward population trend for fin whales in Southern California.

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A fin whale off Southern California.

A new study led by researchers at Scripps Institution of Oceanography at UC San Diego indicates a steady population trend for blue whales and an upward population trend for fin whales in Southern California.

Scripps marine acoustician Ana Širović and her colleagues in the Marine Bioacoustics Lab and Scripps Whale Acoustic Lab intermittently deployed 16 High-frequency Acoustic Recording Packages (HARPs)--devices that sit on the seafloor with a suspended hydrophone (an underwater microphone)--to collect acoustic data on whales off Southern California from 2006-2012.

Blue and fin whales are common inhabitants of the Southern California Bight, the curved region of California coastline with offshore waters extending from San Diego to Point Conception (near Santa Barbara, Calif.), but little is known about their use of the area.

As described in the June 24 issue of the journal Endangered Species Research, Širović and her colleagues analyzed seven years of acoustic data (26 instrument-years) to study the call abundance of blue and fin whales in the Southern California Bight. The study, largely supported by the Office of Naval Research, provides the first detailed view into the spatial use of Southern California waters by blue and fin whales, the two largest cetacean species in the world. Both are classified as endangered species.

Širović found that blue whale calls were more commonly detected at coastal sites and near the northern Channel Islands, while fin whale calls were detected further off shore, in central and southern areas.

The acoustic data indicate that the blue whale population in Southern California is relatively steady, while the fin whale population is increasing.

"I think it's an interesting difference in trends because both of the species were subject to whaling earlier in the twentieth century, and now they're clearly responding differently," said Širović, assistant researcher in the Marine Physical Laboratory at Scripps.

The acoustic data and overall trends outlined in this study are consistent with another Scripps-led study, but one that used visual data collected from 2012-2013 in the same area as part of the California Cooperative Oceanic Fisheries Investigations (CalCOFI). CalCOFI is a unique partnership led by the California Department of Fish & Wildlife, NOAA Fisheries Service, and Scripps Institution of Oceanography, and it is considered to be one of the world's most valuable marine observation programs.

Published in 2014, the Scripps research conducted through CalCOFI indicated that the blue whale population was relatively steady, while the fin whale population was increasing.

Širović cites the parallel findings between the two studies as evidence that passive acoustics can be used as a powerful tool to monitor population trends for these large marine mammals.

"I think it's very exciting that we see the same trends in the visual and acoustic data, because it indicates the possibility of using acoustics to monitor long-term trends and changes," said Širović.

Presence of a resident fin whale population in Southern California was previously suggested, and the recent study's detection of fin whale calls year-round further supports this idea.

Researchers also found that blue whale calls in the region were generally detected between June and January, evidence that supports the known seasonal migration pattern of blue whales, which tend to migrate from off the coast Mexico (or even as far down as Costa Rica) to Southern California in the late spring. The whales forage through the fall, and then leave in early winter, but researchers aren't certain where they go next.

Although researchers have studied blue and fin whales for years, Širović notes that both species are particularly mysterious, and scientists still don't know some basic information about them, such as their mating system or breeding grounds.

The Southern California Bight is a highly productive ecological territory for many marine animals due to strong upwellings, but researchers have not found any evidence that blue or fin whales are breeding there.

The productivity of the coastal region also makes it a hotbed for human activity, with large cities onshore and ships, commercial fishing vessels, and other human impacts ever-present in the water. Since fin whales generally live further offshore, Širović posits that they might have a slight advantage over blue whales, which tend to inhabit areas where there is more ship traffic--increasing their chances for ship strikes.

"It seems that for fin whales, things are probably improving," said Širović, noting that more research is needed to determine why the blue whale population is not increasing.

"For blue whales, it's a little bit harder to tell. There is a question right now as to whether their population has grown to its maximum capacity, because there are many lines of evidence showing that their population is not growing currently," said Širović. "So the question remains, is it because that's just what their population size can be maximally, or are there factors that are keeping them from growing further?"

Širović hopes that future studies can help identify why there is this difference in population trends of blue and fin whales. Now that she and her colleagues have taken a first look at the broad trends of the two species, they want to dig deeper and look into environmental drivers and other factors and features that may be causing some of the spatial distribution patterns and long-term changes of the whales.

Coauthors of the study included Ally Rice, Emily Chou, John Hildebrand, and Sean Wiggins of Scripps Institution of Oceanography, and Marie Roch of San Diego State University.

The analysis portion of this study was supported by the Office of Naval Research, with data collection and monitoring funded by Chief of Naval Operations N45 and the U.S. Pacific Fleet.

Story Source: University of California - San Diego. "Blue and fin whale distribution in waters off Southern California." ScienceDaily. (accessed June 26, 2015).

Journal Reference:
A Širovic, A Rice, E Chou, JA Hildebrand, SM Wiggins, MA Roch. Seven years of blue and fin whale call abundance in the Southern California Bight. Endangered Species Research, 2015; 28 (1): 61 DOI: 10.3354/esr00676

ABSTRACT: Blue whales Balaenoptera musculus and fin whales B. physalus are common inhabitants of the Southern California Bight (SCB), but little is known about the spatial and temporal variability of their use of this area. To study their distribution in the SCB, high-frequency acoustic recording packages were intermittently deployed at 16 locations across the SCB from 2006 to 2012. Presence of blue whale B calls and fin whale 20 Hz calls was determined using 2 types of automatic detection methods, i.e. spectrogram correlation and acoustic energy detection, respectively. Blue whale B calls were generally detected between June and January, with a peak in September, with an overall total of over 3 million detections. Fin whale 20 Hz calls, measured via the fin whale call index, were present year-round, with the highest values between September and December, with a peak in November. Blue whale calls were more common at coastal sites and near the northern Channel Islands, while the fin whale call index was highest in the central and southern areas of the SCB, indicating a possible difference in habitat preferences of the 2 species in this area. Across years, a peak in blue whale call detections occurred in 2008, with minima in 2006 and 2007, but there was no long-term trend. There was an increase in the fin whale call index during this period. These trends are consistent with visual survey estimates for both species in Southern California, providing evidence that passive acoustics can be a powerful tool to monitor population trends for these endangered species. 
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Antarctic whales and the krill they eat
Study looks whether the feeding habits of fin and humpback whales influence their distribution

Date: May 9, 2016
Source: Springer

The Western Antarctic sector of the Southern Ocean is the regular feeding ground of a large number of fin and humpback whales of the Southern Hemisphere. Around 5,000 fin whales likely migrate to its ice-free waters during summer, along with at least 3,000 humpback whales. These estimates follow a ship-based helicopter survey of whales in Antarctic waters. A net trawl survey for krill* was also conducted to see if the distribution of these whales and specific krill species are connected. The study was led by Helena Herr of the University of Veterinary Medicine Hannover in Germany, and is published in a special issue on "Antarctic Peninsula Shelf Biology" in Springer's journal Polar Biology.

Herr's team produced distribution maps that predict the densities in which humpback (Megaptera novaeangliae) and fin whales (Balaenoptera physalus) likely occur in the Bransfield Strait and Drake Passage. It was found that the two whale species do not share the same habitat or feeding grounds around the West Antarctic Peninsula. An estimated 3,024 humpback whales frequented the coastal parts of the Bransfield Strait in summer 2013, while at least 4,898 endangered fin whales were found along the shelf edge in the Drake Passage.

The krill survey shows that Euphausia superba is the most widely distributed and abundant source of food available to whales in the area. The krill type Euphausia crystallorophias occurs sporadically in smaller numbers near the coast, and Thysanoessa macrura generally beyond the shelf edge.

The relationship between whales and the krill they feed on is not a simple one. At the time of the survey, fin whales fed in an area dominated by Thysanoessa macrura. They are also known to feed on Euphausia superba. Fin whales therefore seem to opportunistically feed on whatever prey aggregates around the shelf edge.

There isn't a clear relationship between humpback whales and the presence of a particular krill species either. The whales seemed to be located in all areas of the Bransfield Strait regardless of how much krill was available. Humpback whales did however tend to occur in sectors with at least a medium concentration of Euphausia superba. Humpback whales seem to have adopted migration patterns and foraging strategies that lead them to areas likely to provide, on average, sufficient amounts of prey.

"In the light of increasing effort by the commercial krill fishery and climate change-related effects on krill biomass, dedicated surveys that target both krill and their main predators, such as baleen whales, need to be undertaken concurrently. This is to monitor and ensure that habitats in the Southern Ocean will continue to support a humpback whale population that has just touched pre-exploitation numbers," says Herr.

Efforts should also be strengthened to investigate the ecology and feeding strategies of endangered Southern Hemisphere fin whales, since little is known about their connection to and dependency on local prey stocks.

* Krill are small crustaceans that feed on plankton. They are the main prey of baleen whales, which lack teeth, but have baleen to filter krill out of seawater.

Story Source: Springer. "Antarctic whales and the krill they eat: Study looks whether the feeding habits of fin and humpback whales influence their distribution." ScienceDaily. (accessed May 10, 2016).

Journal Reference:
Helena Herr, Sacha Viquerat, Volker Siegel, Karl-Hermann Kock, Boris Dorschel, Wilma G. C. Huneke, Astrid Bracher, Michael Schröder, Julian Gutt. Horizontal niche partitioning of humpback and fin whales around the West Antarctic Peninsula: evidence from a concurrent whale and krill survey. Polar Biology, 2016; 39 (5): 799 DOI: 10.1007/s00300-016-1927-9

A dedicated aerial cetacean survey was conducted concurrently to a standardised net trawl survey for krill in order to investigate distribution patterns of large whales and different krill species and to investigate relationships of these. Distance sampling data were used to produce density surface models for humpback (Megaptera novaeangliae) and fin whales (Balaenoptera physalus) around the West Antarctic Peninsula (WAP). Abundance for both species was estimated over two strata in the Bransfield Strait and Drake Passage. Distinct distribution patterns suggest horizontal niche partitioning of the two whale species around the WAP, with fin whales aggregating at the shelf edge of the South Shetland Islands in the Drake Passage and humpback whales in the Bransfield Strait. Krill biomass estimated from the concurrent krill survey was used along with CTD data from the same expedition, bathymetric parameters and satellite data on chlorophyll-a and ice concentration to model krill distribution. Comparisons of the predicted distributions of both whale species with the predicted distributions of Euphausia superba, Euphausia crystallorophias and Thysanoessa macrura suggest a complex relationship rather than a straightforward correlation between krill and whales. However, results indicate that fin whales were feeding in an area dominated by T. macrura, while humpback whales were found in areas of higher E. superba biomass. Our results provide abundance estimates for humpback whales and, for the first time, fin whales in the WAP and contribute important information on feeding ecology and habitat use of these two species in the Southern Ocean. 
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Whales use nested Russian-doll structure to protect nerve tissue during lunge dives

Date: February 16, 2017
Source: University of British Columbia

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Rorqual whales use a Russian-doll-like structure to protect nerve tissue during lunge dives, according to new research by University of British Columbia researchers.
Credit: University of British Columbia

Fin whales use two neatly packed levels of nested folds to protect the nerves along the floor of their mouth during lunge feeding, according to new research from University of British Columbia zoologists.

Large whales balloon an immense pocket between their body wall and overlying blubber to store captured prey during feeding dives -- extending nerves along their mouth and tongue to more than double their length.

"But when they shorten again these nerves have to fold so tightly that they develop bending stretches, which could damage the nerve," says UBC zoologist Margo Lillie, author of the paper in Current Biology. "It surprised me that just folding them up created a problem."

The solution: the nerves use a Russian doll-like structure to nest folds.

"The first level of waviness allows the nerve to extend when feeding. Then the nerve structure is folded at a second level of waviness at a smaller length scale -- that creates enough slack in the shortened nerve tissue to allow it to go around each fold without being damaged."

The whale nerves are so large that Lillie and UBC colleagues Wayne Vogl, Kelsey Gil, John Gosline and Robert Shadwick were able to use microCT to visualize the nerve's 3D structure.

The shape of the recoiled nerve is the same as a river meander.

"The shape is a sine generated curve, which is characteristic of a wide range of natural structures including the jet stream, a buckled rod, and flow patterns in rock," says Lillie.

"The bends tend to be as uniform as possible and this minimizes the work required to make the structure. It's a special, ideal shape."

Rorquals are the largest group among baleen whales, and include blue whales and fin whales. The research was supported by the Natural Sciences and Engineering Research Council.

Story Source: University of British Columbia. "Whales use nested Russian-doll structure to protect nerve tissue during lunge dives." ScienceDaily. (accessed February 17, 2017).

Journal Reference:
Margo A. Lillie et al. Two Levels of Waviness Are Necessary to Package the Highly Extensible Nerves in Rorqual Whales. Current Biology, February 2017 DOI: 10.1016/j.cub.2017.01.007

[Image: fx1.jpg]

•Mechanical response of whale VGB nerves and rat sciatic nerves differ
•Micro-CT images of VGB nerves show large waviness at levels of core and fascicle
•Folding in the recoiled VGB nerve core creates large bending stretches
•Nerve core and fascicles form sine-generated curves

Peripheral nerves are susceptible to stretch injury and incorporate structural waviness at the level of the axons, fascicles, and nerve trunk to accommodate physiological increases in length. It is unknown whether there are limits to the amount of deformation that waviness can accommodate. In rorqual whales, a sub-group of baleen whales, nerves running through the ventral groove blubber (VGB) associated with the floor of the mouth routinely experience dramatically large deformations. In fact, some of these nerves more than double their length during lunge feeding and then recoil to a short, compressed state after each lunge. It is unknown how these nerves have adapted to operate in both extended and recoiled states. Using micro-CT and mechanics, we have discovered that the VGB nerves from fin whales require two levels of waviness to prevent stretch damage in both extended and recoiled states. The entire nerve core itself is highly folded when recoiled and appears buckled. This folding provides slack for extension but unavoidably generates large stretches at the bends that could damage nerve fascicles within the core. The strain at the bends is minimized by the specific waveform adopted by the core, while the existing bending strains are accommodated by a second level of waviness in the individual fascicles that avoids stretch of the fascicle itself. Structural hierarchy partitions the waviness between the two length scales, providing a mechanism to maintain total elongation while preventing the stretching of fascicles at the bends when recoiled.

Attached to this post:[Image: attach.png] Two_Levels_of_Waviness_Are_Necessary_to_Package_the_Highly_Extensible_Nerves_in_Rorqual_Whales.pdf (2.67 MB)
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Far-ranging fin whales find year-round residence in Gulf of California

Date: January 10, 2019
Source: Oregon State University

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A fin whale surfaces in Gulf of California, Mexico, during the 2001 study showing the characteristic black coloration of the body contrasting with the white lower right jaw. Photograph by Craig Hayslip, Oregon State University Marine Mammal Institute, under U.S. National Marine Fisheries Service Permit 369-1757 issued to Bruce Mate.  Credit: Craig Hayslip

Researchers from Mexico and the United States have concluded that a population of fin whales in the rich Gulf of California ecosystem may live there year-round -- an unusual circumstance for a whale species known to migrate across ocean basins.
What makes the discovery even more unusual, researchers note, is that they identified the pattern of movement of the fin whales, which are the second largest whale species in the world, using a satellite tracking data set from 2001. Oregon State University professor Bruce Mate, director of OSU's Marine Mammal Institute and co-author on the study, tagged 11 whales that year and was able to record the movements of nine of them for up to a year.
Since then, the OSU scientists have worked with colleagues in Mexico to further study the whales, in the process identifying via a 2011 photograph at least one female fin whale from the 2001 study -- this time, with a calf, indicating the whales may even stay in the region for breeding and calving.
Results of the study are being published today in the journal PLOS ONE.
"One reason we decided to go back to this data set is that we know very little about fin whales in this region," said Daniel Palacios, who holds the Endowed Faculty in Whale Habitats position at Oregon State's Marine Mammal Institute, and is co-author on the study. "It is fairly remote, it is not densely populated and it requires expensive technology to track whales over time."
"Researchers have known since at least the mid-1980s that fin whales inhabited the Gulf of California, but we just haven't been able to get much information about them. As it turns out, we had an important piece of the puzzle in the tracking data set we just hadn't yet fully analyzed."
The researchers were able to reach several conclusions, based on extensive analysis of the tracking record of the 2001 satellite telemetry data coupled with more recent observations of the region's weather patterns, acoustic data, and studies of potential food for the fin whales, in particular, krill and small fish.
  • There may be as few as 100 or as many as 700 "resident" fin whales in the Gulf of California, with the best guess at around 600. Other migrating fin whales also may visit the region seasonally and intermix with the resident population;
  • The researchers believe the Gulf of California is a microcosm for what fin whales face in the larger ocean environment, where they may migrate for thousands of miles in search of the most productive food resources -- and possibly breeding and calving grounds.
  • The fin whales in the Gulf of California may have everything they need in one location, though they are more likely to spend the warmer months in one part of the gulf and the cooler months in another -- likely in response to changes in prey abundance.
"The Gulf of California has a strong seasonal transition driven by changing atmospheric winds that produce upwelling and productivity," said OSU's Palacios, who specializes in the habitats of whale species. "Over the course of the seasons, different parts of the gulf light up and there are hot spots of productivity. Whales have learned to identify these areas and have adapted their movements to track this seasonal shift."
Fin whales are the second largest whale species in the world after blue whales. They are thought to reach as much as 80 feet in length and weigh up to 100 tons. Heavily hunted during the whaling era, their populations have slowly but steadily rebounded because of international protection and the fact that they consume fish as well as krill and other crustaceans.
As a reflection of this, the global conservation status of fin whales was recently upgraded from "endangered" to "vulnerable" by the International Union Conservation of Nature (IUCN) Red List.
Palacios said he hopes the Oregon State researchers and their colleagues from Mexico can return to the region and utilize newly developed tags that will be able to not only collect location data, but record how often the whales dive, how deep, and whether they are eating.
"Feeding year-round is what separates fin whales, blue whales and related species from other baleen whales," Palacios said. "We think they are finding enough food in the gulf to stay there year-round, but we'd like to document that over a period of years."
The study is important because marine mammals in the Gulf of California are threatened by illegal fishing and boating activity. One fish in particular -- the totoaba -- is illegally harvested by fishermen who sell the swim bladder in Asian markets as a supposed aphrodisiac.
In addition to threatening the fish population, the activity has had significant impact on the world's smallest and most endangered marine mammal -- the vaquita. A member of the porpoise family, its dwindling numbers are partially a result of bycatch from that illegal fishing. Some researchers estimate that only 30 vaquita remain alive in the gulf.
Finally, the ship traffic from illegal fishing in the gulf -- including illegal fishing and drug running -- may lead to increased risk of collisions with whales, which could threaten this population of fin whales, Palacios said.
"There is only one other place in the world that appears to have a resident population of fin whales, and that's in the Mediterranean," he said. "We'd like to find out more about how this unusual population has carved out its niche and what may define -- and threaten -- its success."
The OSU Marine Mammal Institute is headquartered at the university's Hatfield Marine Science Center in Newport, Oregon.

Story Source: Oregon State University. "Far-ranging fin whales find year-round residence in Gulf of California." ScienceDaily. (accessed January 10, 2019).

Journal Reference:

  1. M. Esther Jiménez López, Daniel M. Palacios, Armando Jaramillo Legorreta, Jorge Urbán R., Bruce R. Mate. Fin whale movements in the Gulf of California, Mexico, from satellite telemetry. PLOS ONE, 2019; 14 (1): e0209324 DOI: 10.1371/journal.pone.0209324
Fin whales (Balaenoptera physalus) have a global distribution, but the population inhabiting the Gulf of California (GoC) is thought to be geographically and genetically isolated. However, their distribution and movements are poorly known. The goal of this study was to describe fin whale movements for the first time from 11 Argos satellite tags deployed in the southwest GoC in March 2001. A Bayesian Switching State-Space Model was applied to obtain improved locations and to characterize movement behavior as either “area-restricted searching” (indicative of patch residence, ARS) or “transiting” (indicative of moving between patches). Model performance was assessed with convergence diagnostics and by examining the distribution of the deviance and the behavioral parameters from Markov Chain Monte Carlo models. ARS was the predominant mode behavior 83% of the time during both the cool (December-May) and warm seasons (June-November), with slower travel speeds (mean = 0.84 km/h) than during transiting mode (mean = 3.38 km/h). We suggest ARS mode indicates either foraging activities (year around) or reproductive activities during the winter (cool season). We tagged during the cool season, when the whales were located in the Loreto-La Paz Corridor in the southwestern GoC, close to the shoreline. As the season progressed, individuals moved northward to the Midriff Islands and the upper gulf for the warm season, much farther from shore. One tag lasted long enough to document a whale’s return to Loreto the following cool season. One whale that was originally of undetermined sex, was tagged in the Bay of La Paz and was photographed 10 years later with a calf in the nearby San Jose Channel, suggesting seasonal site fidelity. The tagged whales moved along the western GoC to the upper gulf seasonally and did not transit to the eastern GoC south of the Midriff Islands. No tagged whales left the GoC, providing supporting evidence that these fin whales are a resident population.
[Image: wildcat10-CougarHuntingDeer.jpg]

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