Laura Nielsen for Frontier Scientists
Each spring, wildlife biologist Craig George stands where shore-bound sea ice meets open water at Point Barrow and counts whales. Barrow Alaska is the northernmost town in the united states. The lookout point, accessed daily via snowmobile, is no more than a canvas windbreak atop a pile of ice. Warming spring temperatures thin and break apart the near-coastal sea ice just north of Barrow, forming a narrow open passage preferred by migrating whales. And for eight weeks beginning in early April, Craig George and other researchers working with the North Slope Borough's Department of Wildlife brave the arctic weather, straining to spot glimpses of Bowhead Whales. The whale population spends the summer in the Beaufort Sea, the winter in the Bering Sea, and migrates through the Chukchi Sea during the spring and fall.
The endangered Bowhead whale is uniquely adapted to arctic waters, and spends its entire life near the Arctic, not venturing far south like other whales do to escape the ice. The whales possess a high arched jaw and an insulating blubber layer, which can be up to 1.5 feet thick. With their uniquely adapted head, generally measuring 1/3 of their total body length, the Bowhead whale can punch holes directly through ice in order to breathe. Adults grow to 60 feet in length and weigh about 80 tons. Swimming slowly through the water with mouth open, these gentle behemoths strain water through the baleen that hangs from their jaws instead of teeth in order to catch prey. Their diet consists mainly of zooplankton (small crustaceans like copepods, euphausiids, and mysids) that live near Arctic ice.
[img_assist|nid=163187|title=Bowhead Whale skeleton |desc=by Richard Lydekker, Royal Natural History. Vol 3. (www.archive.org) |link=none|align=center|width=350|height=137]
Bowhead whales were hunted nearly to extinction during the 1800s, and early 1900s by commercial whalers who harvested the whales for the prized oil contained in their blubber.
NOAA is the National Oceanic and Atmospheric Administration. According to NOAA's Office of Protected Resources, "the historic worldwide abundance of bowhead whales prior to commercial exploitation is estimated at about 30,000-50,000. Commercial exploitation drove the worldwide abundance down to about 3,000 by the 1920s."1 Closer to Alaska, NOAA's Alaska Fisheries report the estimated local population "numbered between 14,000 and 27,000 whales prior to extensive commercial whaling between 1848 and 1915. It may have dropped as low as 1,500 whales following the commercial whaling era."2 While there are other stocks (populations) of Bowheads scattered throughout the northern Atlantic and Pacific oceans, many are believed to be in decline. In contrast, Alaska's Department of Fish & Game3 estimates that the Bering-Chukchi-Beaufort stock currently contains at least 90% of the surviving world population.
[img_assist|nid=163188|title=Bowhead Whale (Balaena mysticetus) photographed from above |desc=Photo courtesy NOAA, National Oceanic and Atmospheric Administration and the National Marine Mammal Laboratory's image gallery|link=none|align=right|width=350|height=234]
Researchers have collected visual whale abundance data from Point Barrow, Alaska, since 1978. Craig George, speaking at the American Geophysical Union's Fall Meeting in December 2012, says the observers spot about 1/3 to 1/4 of the total population. They saw 1,200 whales in 1978 and 3,400 whales in 2011. Those numbers are combined with acoustic data sets, or sonigrams (the data is housed at Cornell University), audio recordings that chronicle the songs of the migrating whales. Meanwhile NOAA's Fisheries Service supplies aerial-based photographic images of whales. Those photographs help identify whales via the distinctive white markings on their dark skin (as well as scarring) and aid in corroborating population estimates.
Biologist Craig George estimates the Bering-Chukchi-Beaufort population of Bowhead whales numbers about 14,000 or 15,000. "Bowheads are doing beautifully," he says, "they may have made a full recovery." The population seems to be increasing at a rate of about 3.2% per year.
Native Alaskan Eskimos are allowed to hunt Bowhead whales. The International Whaling Commission allows a certain number of strikes and limits the number of whales which may be landed. The whales' meat is used as a food source, and their bones and baleen are used as materials for handicrafts. Native whalers have found harpoon points embedded in the blubber of newly landed whales which are made out of ivory, stone, and bone. Such harpoons have not been in use since the 1800s. Apparently, Bowhead whales can live longer than 200 years.4 This would make them the longest-lived mammal on earth.
The song of a Bowhead whale is complex. They can sing simultaneously in high and low frequencies, but favor low ones. It is believed that the whales travel in acoustically-linked herds, exchanging information concerning travel, feeding, and mating with other whales. While many whale species sing one song their entire life or favor one song seasonally as a group, the Bowheads seem to possess quite a repetoir. "The song diversity noted here is unprecedented for baleen whales... the size of the song repertoire for Spitsbergen bowheads in 2008 to 2009 is remarkable and more closely approaches that of songbirds than other baleen whales."4 The Arctic ice assists the songs; song waves bouncing off the underside of thick sea ice reverberate through the water, and may help the Bowheads navigate the icy Arctic waters."5
[img_assist|nid=163189|title=Bowhead Whale (Balaena mysticetus) pair |desc=Photo by Dave Rugh courtesy NOAA, National Oceanic and Atmospheric Administration|link=none|align=left|width=350|height=234]
Bowhead whales, protected from commercial fishing, are making an impressive comeback. Their major threats now include entanglement in fishing gear, ship strikes, contaminants from i.e. fertilizer or oil spills, anthropogenic (human caused noise) from offshore oil drilling, orcas, and changes in habitat and food availability due to climate change. When we consider melting Arctic sea ice, offshore drilling, and opening Arctic shipping lanes, we'll have to also remember the fate of the endangered Bowhead whales.
1 "Bowhead Whale (Balaenca mysticetus)" National Oceanic and Atmospheric Administration : Office of Protected Resources
2 "AGVIK! Bowhead Whales in Alaska" National Oceanic and Atmospheric Administration : Alaska Fisheries
4 "Bowhead Whales Live Over 200 Years" ABC News
5 "Spitsbergen’s endangered bowhead whales sing through the polar night" Endangered Species Research