Sitka was a center for Tlingit sea otter trade long before Russians arrived in 1799. Marine mammals remained central to the Southeast economy, in ways we might prefer to forget. When otters were gone, facilities such as Port Armstrong whaling station appeared, converting leviathons to corsets and lamp oil from 1912 to 1922. Today, with most whales endangered, they’re more valuable spouting for tour vessels than clamping waistlines or rendered into lubricant.
Our living marine mammals belong to two separate orders. The Cetacea include whales, dolphins, and porpoises. Carnivora include sea otters, seals, and sea lions. Some biologists place seals and sea lions in a third order—Pinnipedia or “finfeet.” Others suggest seals descended from early members of the weasel family and sea lions are separately derived from early bearlike creatures that became aquatic. If this is correct, the order Pinnipedia is an artificial category.
Cetaceans—Whale ancestors appear suddenly in fossil records about fifty million years ago. Their closest contemporary relatives are even-toed ungulates like pigs (“porpoise” is Latin for “pig-fish”). Cetaceans are now totally aquatic, even bearing young in water, while other marine mammals give birth on beaches or icebergs. Cetaceans have no hind limbs, while other marine mammals retain four appendages, albeit highly modified in seals and sea lions.
Cetaceans include toothed whales—sperm whales, killer whales, and porpoises—and baleen whales, with fringed baleen plates of keratin suspended from upper jaws to trap small prey as water rushes through them. Since baleen whales have teeth before birth, it’s believed they evolved from toothed ancestors.
Humpbacks belong to the rorqual family of baleen whales, whose pleats along throat and belly allow the body wall to expand when sieving huge quantities of water. Humpbacks lunge feed, gliding open-mouthed through concentrations of krill (shrimplike crustaceans) or schooling fish. Another method, first described by Charles Jurasz of Juneau, is bubble-net feeding, in which the whale spirals upward, blowing a curtain of bubbles concentrating prey. The whale then bursts through the surface inside the “net,” trailing foam and fish. Sometimes several humpbacks blow bubble nets in a tightly coordinated group. It’s a good idea not to float above a bubble net in a small boat!
Southeast humpbacks belong to the Central North Pacific population, which feeds from northern British Columbia through Prince William Sound between April and November, and winters mostly in Hawaii (a few overwinter in Southeast). Southeast Alaskan whales comprise a distinct feeding aggregation within that greater population. Mating occurs on the wintering grounds, and since pregnancy lasts about eleven months, calves are born there the following year. Since the calf is nursed for up to eleven months, babies are produced only every other year. Over their life span females may bear up to fifteen calves.
Southeast whale biologists participated in the 2008 SPLASH study (Structure of Populations, Levels of Abundance and Status of Humpback Whales in the North Pacific) summarizing numbers and trends. At that time, the Central North Pacific population was thought to number between 7,120 and 10,425 animals. Estimated annual increase was 7 percent between 1993 and 2000.
While humpback whale recovery is good news, it comes with cost and controversy, just as for crab-loving sea otters. Baleen whales compete with commercial fisheries for herring. Exceptionally long pectoral fins make humpbacks more manueverable in tight quarters than other rorquals. At several Southeast salmon hatcheries, humpbacks perform aquatic ballet between net pens as fry are being released. Managers are not amused.
Humpbacks are often seen breaching and slapping the surface with tail or flippers. They have a small humped dorsal fin well back on the body, and many lumps, or “stovebolts,” on head and jaws. Much of their skin is covered with barnacles, a different species from those on intertidal rocks. These barnacles filter plankton and don’t parasitize the whale, but do create drag, so humpbacks come into shallow waters to rub them off on the rocks.
Other baleen whales—Minke whales look much like small humpbacks and are the second most often-seen baleen whale in Southeast’s inside waters. Unlike humpbacks, they surface snout first. Look for a weak, bushy blow, and no fluke display when diving. Minkes are the world’s most abundant rorquals. Although stable in most of their range, they’re still hunted by Japan and Norway.
Alaskan minkes are considered migratory—a population distinct from that of Washington’s, where home ranges are established. Only selected portions of the Alaskan stock have been surveyed. For example, about 1,000 minkes were estimated between Kenai Fjords and the central Aleutians in shelf and nearshore waters in 2001-2003. Most of these were in the Aleutians in water less than 650 feet deep.
Gray whales don’t reside in Southeast, but large numbers move past the outer coast between summer arctic feeding grounds and winter calving grounds in the lagoons of Baja California. Once called devilfish for propensity to attack whaling boats, they now approach tour vessels for chin-scratching. In addition to straining plankton with short baleen plates, gray whales scoop mud off the bottom and sift out marine worms and shellfish, a unique behavior among whales.
Killer whales—The killer whale, or orca, is the world’s largest dolphin—at thirty feet, the ocean’s pinnacle predator. Seen from a kayak, an orca’s dorsal fin is memorable—two or three feet high on females, and six feet on older males.
Biologists describe nonassociating resident and transient killer whale populations. Resident groups feed on fish and squid, while transients hunt mammals and occasionally sea birds. The term “resident” is somewhat misleading, as pods have ranged eight hundred miles. Resident pods are larger and more flamboyant—leaping and tail-slapping, active at the surface. Summer feeding studies suggest resident pods largely ignore pink salmon, selecting more fat-rich cohos. Some resident orcas are adept at stripping even fattier sablefish and halibut from longlines.
Southeast Alaska appears to lie in the zone of overlap of great killer whale geographies. For both resident and transient behavioral types, northern and southern stocks meet in our waters. Among resident, fish-eating groups, the widespread Alaskan stock reaches as far southeastward as Stikine River. Three pods, named AF, AG, and AZ, and totaling about one hundred whales in replicated counts between 1999 and 2009, hunt within Southeast Alaska, The Northern Resident stock (actually southern from an Alaskan perspective) is centered in British Columbia but ranges as far north as Lynn Canal.
Unlike resident orcas, transients travel quietly, remaining below the surface for up to a mile, usually in groups of five or less. The stealthy travelers can surprise porpoises and pinnipeds in this manner. Harbor seals scarcely react to resident orcas but on hearing or sighting transients, they either hide or leave the water, sometimes even leaping into occupied boats. About five hundred orcas comprise the Aleutian and Western Stock, some of whom overlap with animals of the West Coast Stock, which extends to California and totals about 350.
Harbor porpoises—Even without a close look, swimming styles immediately distinguish harbor from Dall’s porpoises. Harbor porpoises are usually seen close to shore, backs and small dorsal fins rising and falling sedately. These quiet, energy-conserving phocids feed mostly on bottom-schooling fish and cephalopods (squid and octopus). Estimated Southeast Alaskan population is about 17,000.
Dall’s porpoises—Dall’s are the porpoises seen sprinting, kicking up spray in midchannel, or riding bow waves of larger boats. With their black-and-white markings, Dalls resemble miniature orcas. They feed on mid- to deepwater schooling fish and cephalopods, often at night when prey ascend toward the surface. Dall’s porpoises range from our inside waters out over the continental shelf, roaming oceanic waters nearly two miles deep. Population estimates are not available for Southeast Alaska, but the entire Alaskan stock numbers about 83,000. Boat-based surveys may be biased by their attraction to vessels.
Pacific white-sided dolphins—In April 1993, pulling into Petersburg on the ferry, we witnessed the aftermath of an orca attack on a large school of white-sided dophins. Several of the victims had panicked and rushed up on shore. One large male was completely unscarred but had preferred death on dry land to the teeth of his larger delphinid relative. This is a mostly pelagic species that sometimes enters inside waters. There are estimated to be at least 26,000 white-sideds in the Gulf of Alaska north of 45o.
Harbor seals—Like our two common porpoises, seals and sea lions are easily distinguishable by behavior. When a round head comes up quietly, turns 90° or so to take in the view, then slips gently under, it’s a harbor seal. When you hear a vigorous whoosh, and see a bearlike head plowing purposefully through the waves, it’s a Steller sea lion. Harbor seals play at the surface only on special occasions, but sea lions do it routinely, rolling, slapping, and sometimes leaping mostly out of the water.
Harbor seals eat squid, shrimp, and fish, especially pollock and capelin. Steller sea lions consume all these plus more cod and herring. Seals fish more often in estuaries and take more sand lance and eulachon than do sea lions. Seals stay down longer, hunting solitary or hidden prey such as octopus, while sea lions target mostly near-bottom schooling fish.
Many seals and all sea lions give birth on rocky islands mostly free of predation by wolves and bears. In northern Southeast, harbor seals also breed in icy waters near tidewater glaciers, where fast-weaned pups on icebergs are safe from all but winged or paddled harassment.
Although long-distance travel has recently been documented for Glacier Bay harbor seals, Southeast populations are considered mostly nonmigratory, with strong fidelity to haul-out sites in breeding season. Six geographic stocks were defined for Southeast Alaska in 2010. Aerial surveys between 2003 and 2006 yielded an estimated 60,000 harbor seals, exclusive of the Yakutat unit. Largest populations are south of Stikine River; the Clarence Strait stock has nearly five times more seals than the comparably-sized Glacier Bay-Cross Sound unit.
Steller sea lions—Our cacophonous otariids breed principally on storm-denuded rocks off the outer coast. Largest colonies are at Forrester, Hazy, and White Sisters Islands. Haulouts viewable from tour ships include Benjamin Island, near Juneau, and Marble Islands in Glacier Bay. Large males exceed a ton—more than three times the weight of females. Unlike harbor seals, sea lions can turn their hind flippers forward for walking. It’s amazing to watch a ten-foot breaker crash harmlessly over a sea lion’s back as it clambers determinedly up the precipitous haulout ramparts.
Northern fur seals don’t reside in Southeast, but females and young pass by our outer coast in transit between pupping grounds in the Pribilofs and wintering waters as far south as California.
Sea otters—These eighty-pound marine weasels favor submerged reefs off rocky beaches. Sea otters give birth at any time of year. Unlike harbor seals, pups enjoy prolonged maternal tutelage. Diet reflects tenure of occupation: on first arrival, colonists enjoy large crabs, octopi, and juicy urchins; later, as pickings diminish, otters make do with small molluscs, snails, and crustaceans.
In the early 1700s, sea otters numbered 150,000 to 300,000 worldwide. When finally protected by international treaty in 1911, less than 2,000 remained in thirteen colonies—none in Southeast. In the mid-1960s, 412 otters were reintroduced to six sites along our outer coast. From those well-chosen nuclei, much of the sea otter’s former range has been recovered; about 10,000 animals inhabited Southeast as of 2012. Glacier Bay—distant from any of the reintroduction sites—has been closely monitored. By 2006 the National Park hosted 2,785 sea otters—a growth rate too rapid for reproduction alone, suggesting substantial immigration.
Unlike other preceding marine-mammal range maps, our map of sea otter concentrations was assembled from various unofficial sources and personal observations and should be considered incomplete. Although sea otters are occasionally sighted deep into the Archipelago (sidebar A puzzling entanglement), trend data suggest rate of expansion into inner, protected waters has slowed notably.
Ups and downs—Although stewarded today by the Marine Mammal Protection Act of 1972, most Southeast species are recovering from numbers reduced nearly to vanishing. Those survivors were vestiges of prior opulence that geneticists are venturing to reconstruct statistically. Some estimate that pre-industrial humpback whale populations, for example, were vastly larger than figures derived from whaling-ship logs. Imagine not dozens but hundreds of thirty-ton keystone krill-recylers, mowing and manuring the pastures of our sea.
Most marine trends are invisible, even to cutting-edge science. Cause-detection is a guessing game, as are recovery strategies. Meanwhile, rapacious global markets seek foods progressively lower on food pyramids. Escalating herring and pollock fisheries compete with baleen whales for food. Well over half of all United States trawl catches come from Steller sea lion habitat.
Steller sea lions are divided into Western and Eastern “distinct population segments” (DPS) at Alaska’s Cape Suckling. While the Western DPS has plummeted, the Eastern DPS (our group) is considered stable or increasing. In 2012, federal managers proposed to remove the eastern Steller sea lion, classified “threatened,” from the list of endangered wildlife. Within that Eastern DPS, the estimated Southeast Alaskan non-pup population increased 88 percent (from 6,376 to 11,965) between 1979 and 2009.
Glacier Bay harbor seals declined about 75 percent from 1992 to 2002, and more recent counts suggest the trend continues. Hunting is prohibited in the National Park, so why are numbers dropping faster here than almost anywhere in Alaska? “Bottom-up” hypotheses include climate change and shifting prey abundance. In the East Arm, for example, grounding and cessation of glacial calving in 1993 eliminated floating ice resulting in abandonment of upper Muir Inlet. “Top-down” possibilities include tourism impacts, orca predation, and sea lion competition. And finally, telemetry studies show unexpected migrations from Glacier Bay breeding sites to wintering grounds as distant as Sitka and Prince William Sound. Three of those seals wandered more than a thousand miles. As with migratory birds, these travels hint that declines among Glacier Bay breeders could well be unrelated to changes within the Park.
The world’s oceans are in trouble. Vast dead zones bracket heavily developed shores, where jellyfish and toxic dinoflagellates dominate the fauna, and large vertebrates are functionally extinct. In coastal seas, large whales have declined 85 percent, sirenians 90 percent, pinnipeds and otters 55 percent, shorebirds 61 percent, sea turtles 87 percent, and oysters 91 percent. In deeper pelagic waters, large predatory fish fell 90 percent since 1950.
What a miracle then, to live where all nine of the commonest marine mammals—with only localized exceptions—are deemed stable or increasing overall! Certainly, fate of other oceans withers complacency. Marine microfossil studies of system-unravelling show zero examples of complete recovery to predegradation benthic communities. And yes, the Tongass mourns its own cetacean and human tragedies. Only coastal resilence—little aided by human wisdom or restraint—fetched back our sea-fauna from the still-yawning brink. Rose-colored glasses are useless to sea-lovers.
But it slights the Tongass not to celebrate her flippered denizens. For those who reside within daily earshot of huffing, submarine lungs, the fat of the land, often enough, is an emanation from the sea.