Cruise track for HEALY Arctic West Summer Cruise 2008, Leg 4.

The principal work of the first evening included the project of Kate Stafford from the University of Washington, who is retrieving and redeploying moorings placed on the seafloor which are equipped with hydrophones to listen for the sounds of various marine mammals, including seals, walrus, and beluga whales, but with particular emphasis on recording the sounds of bowhead whales (Balaena mysticetus), the sounds of which can be heard at: http://www.dosits.org/gallery/marinemm/15.htm.

The bowhead whales are one of the key marine species in the ecosystem, and important for traditional Inuit culture — their meat and blubber a source of food, and their bones used as sled runners and in house construction. Their baleen (the horny plates in their mouths with which they filter the small shrimp-like euphausiids and copepods — their main food), as shown in the baleen model boat in Day One’s blog, was put to many traditional uses in Inuit culture: as a tough cordage for seal and fish nets; for short lanyards and lashings on sleds; as the tip of dogsled whips; for hunting snares for birds and rabbits; bent into boxes for keeping harpoon heads; made into traditional Inuit snow goggles to prevent snow blindness from glare off snow and ice; as a brow on hats for kayakers to keep spray out of their eyes; as fletching on spears and arrows instead of feathers; and as large knives for cutting ice for igloos, and smaller story knives used to tell stories by ‘drawing’ in snow or dirt. Baleen was also woven together without being cut to form racks hung from the ceiling for general storage, and as floorboards in the traditional semi-subterranean Inuit houses shown in the Day One blogs: a sort of Inuit linoleum! And, in earlier times when warfare between native groups existed, it was also used as plates woven together in the construction of armor. Making of woven baleen baskets was an innovation of the late nineteenth century begun by Barrow resident Charlie Brower.

The bowhead whale is still the principal whale hunted off Barrow. Getting an accurate count of bowhead whales has been a key issue for scientists and the Inuit people for many decades to ensure their proper management and conservation. Preliminary information on the results of the annual aerial survey, along pictures of bowhead whales may be found at: http://www.afsc.noaa.gov/nmml/cetacean/bwasp/index.php. Kate’s hydrophone arrays are deployed offshore of the 100 meter depth line at two locations along the coast in groups of three to allow tracking of whales passing along the coast. Their batteries allow them to operate for a year. In the first day of science, the arrays already deployed from the previous year are retrieved by positioning the ship over their location and generating a specific series of tones which activates an acoustic release. Floats which had remained submerged with the hydrophones are then released from their bottom weights, and the hydrophone and floats drift up to the surface where they are located by a small boat, and passed off to the ship, which then hoists them back onto the deck.

Coast Guard small boat used to retrieve moorings by snagging their floats after release from seafloor.

Once the hydrophones are retrieved, Kate downloads the data from the past year collected by the hydrophones, changes out the batteries and data recording computer hard drives, and later in the cruise will redeploy them. Of concern when retrieving the hydrophones is the ability to find them if there is heavy ice. High resolution (100 meter) satellite images have been requested by the ship showing where the ice is located.

100 meter resolution Radarsat satellite image showing ice concentrations in Beaufort Sea off Barrow, Alaska.

This imagery is from a Radarsat satellite, which is particularly useful as it can see through the ubiquitous fog. In areas where ice concentrations are heavy, hydrophone retrieval can be delayed until the ice has moved away, and the likelihood of retrieving the moorings is more certain: better to wait a bit for conditions to improve than risk a full year’s data.

The principal components of hydrophone mooring array, shown in the photo below being disconnected from the cable by Kate Stafford of the University of Washington and John Kemp of the Woods Hole Oceanographic Institution, are the hydrophone and acoustic release. When the mooring array is redeployed, a float is put over the side first. It is the float which provides the lift to allow the hydrophone and acoustic release to surface, be located by a small boat and retrieved. After the float goes over the side, the hydrophone, and then acoustic release go over, and last of all the weight for the mooring anchor is put over the side. When everything is in the water, the ship is positioned precisely over the desired mooring location, and a manual release is used which, when a rope attached to it is pulled, drops the weight at the correct location, and the entire array is pulled downward to the bottom, where it remains until the ship returns to ‘ping’ the acoustic release with the precise acoustic series of tones to retrieve it a year hence.

Hydrophone and acoustic release mooring components.

Float, weight, hydrophone and acoustic release.

Manual release for weight.

Bowheads were among the whales fairly heavily hunted during the golden days of whaling in the second half of the nineteenth century. Bowhead populations in advance of this period have been cited as about 16,000 animals, although of course, it is impossible to know for certain their historical abundance. The current estimate of the Beaufort-Chukchi-Bering Sea bowhead population is about 8,000-10,000 animals. The numbers of these whales seems to be stable and actually increasing. It is important to get good data on their numbers and habitat use as changes occur in sea ice and ship traffic in the Beaufort and Chukchi Seas.

Each year the bowhead whales migrate south through the Bering Strait in the winter to avoid seas completely covered with heavy ice, so that they can continue to surface and breathe. In the spring they migrate north from the ice edge in the Bering Sea into and through the Chukchi Sea, and many migrate north around Barrow and then east along the coast toward the Canadian arctic and Northwest Passage channels. Maps of the migration routes of some whales tagged by Alaska Fish and Game Department personnel can be seen at http://www.wildlife.alaska.gov/index.cfm?adfg=marinemammals.maps&name=8-10.jpg. As winter arrives, the whales return south along the coast to the Bering Sea.

Interestingly, the bowhead whales are often accompanied north by beluga whales (Delphinapterus leucas), the truly “white whales” of the northern seas. Because of their much smaller size, the belugas cannot easily break through the ice to make breathing holes themselves, and follow the bowhead whales using them as their own ‘icebreaking vessels’ to access more northerly waters in spring. Once in the Beaufort Sea the bowhead whales appear to distinctly prefer the waters closer to shore along the Alaskan North Slope, while aircraft sightings and tagged animals show that belugas remain further offshore in deeper waters, with a fairly distinct separation of habitat use. The fact that bowheads prefer the more nearshore waters along the North Slope makes them potentially more susceptible to increased human activities, and Kate’s project all the more important to contribute to continued monitoring of population levels.

Hunting whales by certain arctic peoples is much more than simply an avocation or way of harvesting food. This is perhaps difficult for outsiders to fully comprehend, but whaling in traditional Inuit and other arctic whaling cultures was, and still is, almost a religious or deeply spiritual enterprise, surrounded with rituals of moral purification and behavioral restrictions. It is still emphatically pointed out that one does not actually hunt whales, but one simply goes hunting for whales: it is the whale that gives itself to the hunter and whaling crew which has strictly maintained the traditions associated with successful whaling. In the arctic this invariably includes, among many other things, widespread distribution of the animals taken to everyone in the community, and other communities as well, practices which are still sustained. George Naekok, who is with us as an Inuit observer on this cruise, has been whaling most of his life.

Barrow resident George Naekok.

Insignia of the Barrow crew which includes George Naekok.

The Artic summer welcomes many species of whales back from lengthy migrations, including the gray, blue, fin, and minke whales, but a fascinating trio—the bowhead, beluga, and narwhal—make their home in the Arctic and subarctic year round.

Bowhead

The 50-to-60-foot-long (15 m–18 m) bowhead spends its life near the edges of the sea ice, migrating as the ice expands or recedes with the seasons. It’s protected from the cold waters by a thick layer of blubber, and its exceptionally strong triangularly shaped skull lets it break through a foot (30 cm) or more of ice to breathe.

A bowhead breaking through the ice. Illustration by Craig George.

The bowhead is a baleen whale. Instead of teeth, it has several hundred fringed plates, called baleen, that hang down from its upper jaw and filter small prey from the water. When feeding, the bowhead swims with its huge mouth open, taking in enormous amounts of water and trapping copepods, krill, and other drifting crustaceans.

Bowhead whales are the only species of baleen whale that live in the Arctic year round.

To some indigenous Arctic people, such as the Iñupiaq of the Barrow, Alaska, area, the bowhead has been a major food source, with the whale hunt a centerpiece of their culture for at least 2,000 years. Commercial hunting, which took place mainly between the mid-1800s and the early 1900s in the western Arctic, has been banned since 1946, but the International Whaling Commission allows subsistence hunters to take a specified number of bowheads each year.

Bowhead whale bones, like these in Barrow, Alaska, are a common site in areas with populations of subsistence hunters.

The long history of bowhead hunting is helping to shed light on the lifespan of these whales. Several bowheads caught near the turn of the twenty-first century were found with old harpoon tips in their bodies, while others contained stone spearheads. In conjunction with other evidence, these weapons suggest that bowheads can live for well over a hundred years—quite possibly making them the world’s longest-lived mammals.

The bowhead got its name because its upper jaw has some resemblance to an archer’s bow. Its head is immense, making up about one-third of its body length.

Beluga

Beluga whales by the edge of the ice.

As the bowheads migrate northward, following cracks in the ice known as leads, they are often accompanied by belugas. One beluga population migrates from the Bering Sea to the Beaufort Sea, as does the main population of bowheads. But the two whales are quite different.

The beautiful beluga, also known as the white whale because of its adult coloring, is of medium size as whales go, with a maximum length of 20 feet (6 m). It’s a toothed whale with a varied diet that includes fish, squid, shrimp, and marine worms. The beluga itself is prey for orcas, polar bears, and some indigenous Arctic people.

A friendly surfacing beluga.

Belugas are a sociable bunch, often gathering in large numbers, and most of them are chatty as well. Their vocalizations, which include whistles, clicks, and grunts, earned them the nickname “sea canary.” In the summer, different groups of belugas will come together in the relatively warm waters of estuaries and the nearby coastal waters. Beluga mothers seem to find the quiet estuaries ideal for raising their newborns or yearlings—but it’s also a good environment for the belugas to molt. They have extremely thick skin that they shed all at once each summer, often rubbing on the bottom of the estuary to speed the process along. New skin cells grow rapidly.

Like bowheads and narwhals, belugas have no dorsal fin– enabling them to swim more easily under the ice.

Once commercially hunted, the much-admired beluga is now a star attraction in the growing ecotourism industry. It‘s also a poster child for ocean conservation. As a top predator, it’s being contaminated by toxic chemicals that are concentrated high in the food chain.

Narwhal

Closely related to the beluga, the slightly smaller narwhal that’s found primarily in the eastern Arctic shares many biological and ecological characteristics with the white whale: It’s usually found in groups, it’s quite vocal, and it has a similar diet. What distinguishes the narwhal from the beluga—and from all other creatures—is its magnificent tusk.

The tusk of a full-grown male narwhal can extend up to half of the whale’s body length.

Unlike the tusks of elephants and other animals, the narwhal tusk is a tooth. This whale has two teeth. In the male, the left tooth grows out through its lip, reaching a length of about 9 feet (3 m). A small percentage of females grow a shorter tusk, and males occasionally grow double tusks.

During medieval times, narwhal tusks were sold for vast sums in Europe as unicorn horns, which were thought to cure a variety of diseases and even to neutralize poisons. It wasn’t until the late seventeenth century that the origin of the tusks started to become known.

A drawing from 1820 of a narwhal– or, as labeled here by the illustrator, a “unicorn.”

But the discovery of the “unicorn of the sea” created a scientific puzzle—what was the purpose of the tusk? Many theories were proposed; for example: males dueled with their tusks, they impressed the ladies, they punched holes in the ice; they poked the ocean floor to find food. None of the long laundry list of theories gained general acceptance, though.

In 2000, dentist and marine mammal researcher Martin Nweeia, long fascinated with the narwhal’s extraordinary tooth, became the principal investigator for the Narwhal Tooth Expedition and Research Investigation. A multidisciplinary team was established, and what they found was remarkable. Using an electron microscope, the researchers determined that about 10 million nerve endings tunnel from the core to the outer surface of the tusk. That makes the tusk an incredible sensory device, capable, the scientists think, of detecting slight changes in temperature, pressure, and much more. The tusk might let a whale know when the sea is about to freeze over, for example, or give it other life-sustaining information about its environment.

While narwhals are often spotted swimming in groups of 15 to 20, narwhal gatherings of hundreds– and even several thousand– have been reported.

The narwhal is faced with the same threats as the beluga, but it’s under additional pressure from hunting because of its valuable tusk. A tusk sells for several thousand U.S. dollars, while a rare skull with double tusks can cost $30,000 to $50,000, and sometimes even more. The United States and a few other countries forbid the import of narwhal tusks, but there are markets around the world clamoring for them. Scientists and environmentalists urge better oversight of narwhal hunts as well as lower, strictly enforced catch limits.