#WhaleWednesday – Sperm Whale

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© Douglas Hoffman

Sperm Whales are the largest of the toothed whales and the largest living carnivore. The sperm whale is easily recognized by it’s massive head and prominent rounded forehead. They have the largest brain of any creature known and their heads hold a large quantity of spermaceti (milky white waxy substance in the head cavity). During the days of commercial whaling, sperm whales were so named  because when the head was cut open it was found to contain a milky white substance and the whalers once believed that the fluid was sperm.  Spermaceti is a high quality oil and was used originally in lamp oil and later as an industrial lubricant, in cosmetics, automatic transmissions, and pharmaceutical compounds, making this species highly valuable to whalers.

Scientists still do not fully understand the function of spermaceti. One common theory is that fluid, which hardens to wax when cold, helps the whale alter its buoyancy so it can dive deep and rise again. Sperm whales are known to dive as deep as 3,280 ft in search of squid to eat, which means these whales must hold their breath for up to 90 mins on such dives.

 

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© Douglas Hoffman

Sperm Whales have 20-26 pairs of cone shaped teeth in their narrow lower jaw. Each tooth is 10-20 m long and can weigh as much as one kilogram. However, the existence of teeth in sperm whales is a bit of mystery as the teeth are not considered to be necessary for feeding on their primary food item, giant squid. Some sperm whales have scars on their bodies caused by giant squid tentacles during fights. Although sperm whales are known to eat a wide variety of sea creatures their primary prey items are deep-water squid which they are believed to catch by the suction method of eating.While sperm whales can dive to depths of up to 1 km to locate the rarely seen squid, most dives are to approximately 400 m and last for 35 mins to 1 hour. After a long dive, sperm whales remain at the surface for around 8 mins – it is during this time that sperm whales were most susceptible to whalers.

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© Douglas Hoffman

Sperm whales can be quite gregarious and known to breach, spyhop (vertically pokes it head out of the water) and lobtail (sticking their fluke out of the water into the air, swing it around, then slap it on the waters surface). A sperm whale spends most of its life in either nursery schools (adult females with young) or bachelor schools (males between 7 & 27 years of age) although older males tend to live on their own in very small groups and join nursery schools during breeding season. The only natural predator of the sperm whale is the orca and even then most attacks are not thought to be fatal. During such attacks however, the females show defensive behaviour of calves by creating a ring with the calves in the centre, called a marguerite. These rings may have their heads or tails on the outside.

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Sperm whale adult males grow to be about 50-60 feet long, weighing about 40-50 tons, whereas females are smaller about 33-40 feet long, weighing 14-18 tons. The four chambered heart of the average sperm whale weighs about 277 pounds! Sperm whales have flipper that are about 5 feet long and 3 feet wide, they do not have a dorsal fin but there is a small hump two-thirds of the way down its back. There are also ridges between the hump and the tail flukes.

Sperm whales are found in most of the world’s oceans, except the high Arctic and prefer deep water. They can be found in large numbers where food is abundant, and where the sea temperature suits them.

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© Douglas Hoffman

The species has been drastically affected by commercial whaling in the past and numbers are thought to have been decimated. Sperm whales are still threatened by hunting, principally by Japan. The current worldwide population is not known and the conservation status of the sperm is listed as Vulnerable.

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Video: Friendly Sperm Whale

 

 

 

 

#WhaleWednesday – Common Minke Whale

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Last week on #WhaleWednesday you read about the Antarctic Minke whale this week you’ll learn about the Common (or Northern) Minke Whale

Minke whales are the smallest and most abundant of the rorqual whales. They have a sharply pointed snout, straight mouth line and a long ridge along the head with two blowholes. They have hundreds of baleen plates 20 to 30cm long growing from their upper jaws and between 50 and 70 pleats running from their throat and ending just past their flippers. These pleats stretch, allowing the whale to take in huge volumes of water when feeding. Minke whales have a streamlined shape and smooth skin with no callosities or barnacles. They are black, dark brown, or grey on their upper side with a lighter belly and a dorsal fin positioned far behind the centre of their back. Minke whales in the northern hemisphere have a white band on each flipper, though many in the southern hemisphere do not. The fluke of a minke whale is rarely seen above the surface.

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You are more likely to see minke whales at close quarters than other baleen whales because they are notoriously inquisitive and often approach boats.

The minke whale is the smallest of the rorqual whales. Females reach an average length of 8.5m and males grow to about 8m. Like other baleen whales, those found in the northern hemisphere tend to be smaller than those from the southern hemisphere. Minke whales weigh between five to 10 tonnes.

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The minke is widespread and seasonally abundant in the North Atlantic Ocean. In the winter, they migrate southwards, although it is unclear where their breeding grounds are located. In summer, concentrations shift northward to Spitsbergen and the Barents Sea, the coast of Norway and the waters off Iceland, Greenland and Newfoundland. In the northern Pacific, minkes are found in the Bering and Okhotsk Seas, and Gulf of Alaska in the spring and summer.

Like other great whales, minkes migrate to temperate and tropical waters in winter and polar waters in summer. Minke whales are often solitary, although they often travel in pairs or groups of three. In higher latitudes they are sometimes found in larger groups.

Common minke whales are generally solo marine mammals and prefer to travel alone, however in some cases they may be accompanied by one or two other whales. During small gatherings groups may expand to 4-10 minke whales but these occurrences are rare.

In the eastern North Pacific and North Atlantic, breeding may occur throughout the year, but there appears to be a calving peak in winter. The gestation period is believed to be around ten months. Females give birth to a calf every 12 to 14 months. Killer whales prey on minkes, as do other natural predators. They are believed to live to 40 to 50-years-old.

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Minke whales tend to feed on the food source that is most abundant in a given area, primarily krill and small schooling fish, but occasionally larger fish such as mature arctic cod and haddock. In the North Pacific, minke whales reportedly feed on euphausiids, copepods and sand eel, and those in the Okhotsk Sea feed on krill, and sometimes fish. In the North Atlantic, minke whales feed on a wide variety of prey, including sand eel, euphausiids, copepods, salmon, capelin, mackerel, and cod.

Northern minke whales are caught in the North East Atlantic by Norway pursuant to an objection to the International Whaling Commission’s (IWC) whaling moratorium, and by Greenlanders as “aboriginal subsistence” whaling. Japan hunts 150 whales a year in the North Pacific under their “scientific” reasearch permit. Japan also hunts up to 440 southern minkes a year in the Antarctic under their “scientific” research permit.

Minke whales are know to face attacks from groups of killer whales in areas where these predators are know to hunt other marine mammals. Numerous cases of minke whale meat being found in a killer whales stomach have been confirmed along with injuries and scares being observed on minke whales that have successfully escaped being killed. There are also a number of cases where dead minke whales have been spotted eaten by groups of sharks which my indicate that they are either hunted by sharks or the sharks wait for the whale to die and then consume the carcass.

The common minke whale global population however is currently under review by the IWC whilst little information is available for the dwarf minke whale. The species is listed as of Least Concern by IUCN (2008).

Video: Bait Ball – Common Minke Whale lunge feeding

#WhaleWednesday – Antarctic Minke Whale

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The minke whale is the smallest rorqual whale and, as such, was the last to be targeted by whalers. Until the turn of the century, the minke was treated as one species but it is now widely accepted that there are two species: a common minke and an Antarctic minke whale. The latter overlaps in its distributional range with a small form of the common minke, sometimes called the dwarf minke whale.

The Antarctic minke whale is among the smallest of the baleen whales, with only the common minke and the pygmy right whale being smaller. Males can reach a length of 35 ft and females approximately 32 ft in length, and adult minke whales can weight up to 15 tonnes.

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The body colour is usually black or dark brown with streaks of paler colour on their lateral sides, and a distinctly paler belly. It has a notably pointed rostrum and a single ridge on its head. This species often has a yellow wash to its baleen as a result of diatom growth. Most importantly, the Antarctic minke lacks the distinctive white flipper mark that is found in the common minke whale.

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Antarctic minke whales are known from around 7º S to the ice edge (and into the ice fields) during the austral summer (November through March). There they feed mainly on krill and, in turn, are important prey items for the orca that also live in these waters. They will occasionally approach smaller boats when feeding. The Antarctic minke whale is usually found alone or in pairs, although aggregations of hundreds of whales can gather in feeding grounds.

The antarctic minke whale reaches sexual maturity at 7 to 8 years old and has a lifespan of approximately 50 ears. The species mates over the winter and the female undergoes a 10 month gestation period, usually giving birth to a single calf, although twins and triplets may sometimes occur. The calf typically suckles for 5 months before being weaned, and will remain with the female for up to 2 years.

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Distribution Map: Minke whales are the only baleen whale species which is still most common in Antarctic waters and the most ice adapted of the Antarctic baleen whales. They have been seen hundreds of kilometers into heavy pack ice in the middle of winter and some of them obviously spend winter there. In summer, their favourite habitat seems to be open pack ice, that is, pack ice where there is quite a lot of open water among ice floes.

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Minke whales (both Antarctic and common) continue to be hunted in large numbers by the Japanese whaling fleet, who claim to kill minke whales for “scientific research”, but they are simply attempting to recommence commercial whaling. The meat from this research is sold in commercial markets. Since 2005 Sea Shepherd Conservation Society has used its ships to disrupt Japan’s annual whaling expedition in Antarctic waters. (Be sure to check out the TV series Whale Wars) However this year, Sea Shepherd has announced it is suspending the campaign, since the Japanese whalers have doubled their whaling grounds and are now employing military surveillance to watch Sea Shepherd ship movements in real time by satellite. The result is that Sea Shepherd cannot compete with their military grade technology. Captain Paul Watson, founder of Sea Shepherd Conservation Society, has stated that Sea Shepherd will regroup with different strategies, tactics and an alternative way to dealing with the Japanese whalers.

Like other cetaceans, the Antarctic minke whale is also vulnerable to chemical and noise pollution. Climate change will also be a major threat to this species. With rising temperatures, a reduction of sea ice means the Antarctic minke whale may lose between 5 and 30 percent of ice associated habitat in the next 40 years. As the area of suitable habitat reduces and prey populations decrease there will be an increase in competition for space and food, ultimately decreasing the population of this whale species.

They are categorized as Data Deficient by the IUCN Red List (2008).

 

Video: Curious Antarctic Minke Whale

 

 

#WhaleWednesday – Bowhead Whale

 

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One of just three year-round Arctic whale species, bowheads, are famous for their massive bow-shaped heads, designed perfectly for one of their main challenges: getting through think sea ice to breathe. Bowheads are able to use their large reinforced skulls and powerful bodies to break through ice 20cm thick. Although Inuit hunters in Alaska have reported whales surfacing though approximately 60cm of ice. Their Heads make up about a third of the total length – which in adults can be up to 20 metres – newborn calves are about 4 metres long and weigh 2-3 tonnes.

Bowhead whales are also known in quiet Arctic waters for their intense bouts of social group interactions, involving tail and flipper slapping, as well as breaching (leaping entirely out of the water) – which is an impressive feat for whale that weigh up to 100 tonnes.

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Whales are close to the top of the food chain and important indicators of overall health of the marine environment. The bowhead whale’s conservation status is listed as “Least Concern” overall, however some populations, such as the East Greenland-Svalbard population are endangered.

Data has shown that bowhead whales may be among the longest-lived animals on earth. Based on the recovery of stone harpoon tops in their blubber, and from analysis of eye tissue, scientists believe that the life span of bowhead whales can be over 100 years.

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Like the other ice whales (beluga and narwhal), bowheads also have no dorsal fin, enabling them to move easily under the sea ice. Bowheads can dive for over 30 minutes at a time. They typically spend the entire year in Arctic waters, their travels shaped by the melting and freezing of the ice, and seasonal movements to a series of spring-summer productive feeding areas. They have a very thick layer of blubber – approx 40-50cm – which serves primarily as an energy store to see them through the annual cycle.

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Bowheads are baleen whales, with about 250-350 keritanous baleen plates on each side of their upper jaw. These massive vertical plates – up to 4.6m long in fully grown individuals, the largest of any whale – to filter their food from the hug open-mouth gulps of water that they take. Bowhead whales need to eat about 100 tonnes of food annually, mainly tiny crustacean zooplankton. Most of their annual feeding occurs in the summer months, and much of that in the Canadian waters.

The bowhead whale has been a victim of the appeal of its long baleen plates and thick blubber – the most economically valuable whales. Hunted by commercial whalers until the last century for whale oil and baleen, bowhead whales are still recovering slowly from their economic extinction. While some populations are faring better as a result, it will take many more decades for this long lived and slow reproducing species to recover to its pre-whaling numbers. Inuit in Canada, Greenland and Alaska are allowed a limited subsistence hunt for bowhead whales.

Threats: Modern threats to bowhead whales include sea ice retreat and changes to food web dynamics due to rapid climate change and ocean acidification. Bowheads are also affected by direct and indirect impacts of increased development such as oil and gas exploration, commercial shipping, and fishing.

The Canadian and Alaskan governments have attached satellite radio transmitters to a sample of bowhead whales, in order to better understand seasonal movements and habitat use of these Arctic giants. This information can be used to identify and protect the most important areas used by these whales, and to help plan further human activities, like shipping and development, in these sensitive, quiet arctic waters – the bowheads’ home –  and in all decisions regarding the future of Arctic marine systems facing rapid climate and economic change.

 

 

#WhaleWednesday – Gray Whale

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Gray whales have a hump and a ridge of sharp bumps along their back, instead of a dorsal fin, and can be between 40 and 50 feet long. They are a type of baleen whale, meaning they filter food from the water through special bristly structures in their mouths. Gray whales stay close to shore and feed in shallow water. Their migrations take them between feeding and breeding areas, swimming as much as 12, 000 miles per trip.

Critically endangered western gray whales migrate into their summer feeding grounds near Sahkalin Island, Russia in May or early June and then return to their winter feeding grounds in the the South China Sea in late Autumn.

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The eastern population of the gray whale can be found in the Bering and Chukchi Seas between Alaska and Russia during the summer feeding. In the winter, the eastern gray whale migrates south along the west coast of the US to Mexico to breed and have their calves.

The Gulf of California’s San Ignacio Lagoon is one the best places in the world to see gray whales with their calves. The calm, warm waters of the lagoon are a safe place for young whales, free from predators like killer whales. Locals in the area, call gray whales “friendly ones” as they have an unusual tendency to approach whale watching boats and check out the occupants.

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Threats: Oil and gas development, entanglement in fishing gear, and collisions with ships threaten gray whales. The western North Pacific gray whale is on the verge of extinction because of such threats. The waters off Russia’s Sakhalin Island, a main feeding habitat for them in the summer, are being targeted for oil and gas development. In the eastern Pacific Ocean, the potential for oil and gas exploration in the Bering and Chukchi Seas also exists. Whales are very sensitive to noise and such industrial activities generate massive underwater booms. The gray whale must get an entire year’s worth of food during those summer months and any disruption could have significant impact on this process.

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Friendly Gray Whales in San Ignacio Lagoon

#WhaleWednesday – Fin Whale

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The fin whale, the second largest living mammal, has been severely impacted worldwide by commercial whaling. Nearly 750,000 animals were killed in areas of the Southern Hemisphere alone between 1904 and 1979, and they are rarely seen there today. Their current status is unknown in most areas outside of the North Atlantic.

The fin whale is the world’s second largest animal after the blue whale. They can dive to depths of 230 metres and make low-frequency noises (infrasound) which can be as loud as 188 decibels. These sounds cannot be heard by humans, but can be detected by other fin whales up to 850 km away. An individual fin whale is identified by the pattern of light-coloured chevrons on its back as well as by the size and shape of its dorsal fin. Records of females have been found with multiple foetuses, but it is unlikely that more than one would survive. The oldest specimen captured in Antarctica was 111 years old. Fin whales have also been known to mate with blue whales and to produce first generation offspring.

Growing up to 27 metres long and weighing as much as 120 tonnes, the slender body of the fin whale is capable of speeds of up to 37km/h, with brief bursts of up to about 47km/h which led to its nickname, ‘greyhound of the sea’. The upper half of the body is dark grey or brownish, while the belly is white. The head has a single medial ridge and has distinctive asymmetrical markings: on the right side the lower lip, mouth cavity and baleen plates are white, whereas on the left these features are dark. The fin whale has a small, falcate dorsal fin and slightly concave trailing edges to its flukes, which are rarely raised out of the water.

The fin whale feeds on animal plankton (including krill) and schooling fishes, lunging to take in great quantities of water and prey, then filtering the water out through its baleen plates leaving the prey trapped inside its mouth. When a fin whale eats it often turns on its side with the right side facing downward; in this position the lighter head colouration makes it less visible to prey. The fin whale generally travels alone or in pairs, and rarely breaches or spyhops. Its exceptionally large size, asymmetrical head colouration and small dorsal fin are probably the best identifying features. Overall range and distribution is not well studied but they are known to inhabit primarily pelagic habitats of both northern and southern hemispheres. Most populations are thought to be migratory whilst several resident populations are known to exist in the Gulf of California, East China Sea and the Mediterranean.

Extinction Risk:

Fin Whale

 

 

 

Threats:

With krill reduced, will they go too? Fin whales have been greatly affected by historical hunting, mostly due to their economically valuable blubber, oil and baleen. The recovery of the southern hemisphere fin whale may be undermined by, among other things, a reduction of Southern Ocean krill due to climate change.
Pollution: Fin whales are also threatened by habitat degradation. In some regions they have been shown to carry high levels of pollutants such as heavy metals, PCBs and other organochlorine compounds that accumulate with age and transfer between mother and calf during nursing. These substances can cause health and reproductive problems in cetaceans.
Ship strikes: Boat collisions are another serious cause of fin whale mortality, particularly in areas with high-speed vessel traffic. A dead fin whale that was washed ashore in south-west England in early 2010 is believed to have been the victim of a ship strike.

Bycatch: They are also vulnerable to incidental catches in fishing gear, but less so than many other cetacean species.

Whaling: Whaling remains a threat for this species. In 2006 Iceland resumed commercial whaling and in 2009 set a quota for 150 fin whales over 5 years – to date 125 fin whales have been harvested – despite the species’ status as “Endangered”.

Note: Japan is also set to return to a full-scale commercial whaling on the high seas, a move currently blocked by the International Whaling Commission (IWC). But the Japan government has consistently ignored objections and resolutions from the IWC against its scientific whaling and has even ignored a decision by the International Court of Justice that they close down their whaling activities as undermining the IWC. The new Japanese legislation includes funding to repair the aging whale ships being used for the current bogus “scientific” whaling and guarantees funding for whale “research” in the future. Furthermore, the new legislation allows Japan to send vessels to Antarctica with the fleet specifically to deal with harassment from such organizations as the Sea Shepherd Conservation Society, which seeks to interfere with whaling activities they contend violate international law. (Memo to Japan government: Sea Shepherd is right.)

 

Japan has also moved to stop interference with their illegal whaling operations by declaring that anyone who opposes whaling and the killing of dolphins is a terrorist.

Apparently, simply witnessing and documenting the slaughter of dolphins in Japan will now be a crime and classified as terrorism.

#WhaleWednesday – Narwhal

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The narwhal looks like a cross between a whale and a unicorn with its long, spiraled tusk jutting from its head. Males most commonly have tusks, and some may even have two. The tusk, which can grow as long as 10 feet, is actually an enlarged tooth. The tusk may also play a role in the ways males exert dominance.

Narwhals are related to bottlenose dolphins, belugas, harbor porpoises, and orcas. Like some other porpoises, they travel in groups and feed on fish, shrimp, squid, and other aquatic fare. They are often sighted swimming in groups of 15 to 20, but gatherings of hundreds—or even several thousand—narwhals have been reported. Sometimes these groups become trapped by shifting pack ice and fall victim to Inuit hunters, polar bears, or walruses.

Whales, like the narwhal, are at the top of the food chain and have an important role in the overall health of the marine environment. Narwhals are also culturally important to indigenous communities in the Arctic. Like polar bears, the narwhal depends on sea ice for its existence and can be directly impacted by climate change.

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Extinction Risk 

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Threats faced by Narwhals:

Oil and Gas Development – Vessels that support oil and gas development mean increased shipping in sensitive areas. Increased shipping means more noise that can mask communications for many Arctic marine species and it increases the potential for collisions with marine mammals, especially whales. It also brings more pollution and a greater possibility of oil or fuel spills.

Ocean Noise – Shipping, industrial extraction, marine construction and military activities cause underwater noise pollution. Since whales depend on sound to communicate, any interference by noise pollution can negatively affect their ability to find food and mates, navigate, avoid predators and take care of their young.

Climate Change – Thousands of years of evolution have prepared Arctic species like the polar bear, walrus and narwhal for life on and around the sea ice. Because of climate change, that ice cover has been changing rapidly, in both extent and thickness, and shrinking far too quickly for these species to adapt. A narwhal’s entire life is connected to sea ice, both as a place to feed and a place to take refuge. Slow swimming whales rely on sea ice as a place to hide from predators like killer whales.

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