An Accidental Science Project Reveals How Crucial Sea Otters Are to Kelp Forests

Photograph by Norbert Wu/Minden Pictures
Photograph by Ethan Welty
Photograph by Paul Souders

An Accidental Science Project Reveals How Crucial Sea Otters Are to Kelp Forests

Fur traders exterminated them in Washington. A hydrogen bomb helped restore them. These events have given ecologists startling insight into the power of these kelp forest carnivores.

By Susan McGrath
Published: January-February 2014

On a foggy day in mid-September, I go looking for a glimpse of a colossus on the outer edge of Washington State's Olympic Peninsula, the wildest stretch of coastal wilderness in the Lower 48. Olympic National Park doesn't much cater to the faint of heart; it's infamous for its vertiginous headlands and remote beaches where hikers get cut off by rising tides. Fortunately for lilydippers like me, there's a rare soft opening from Lake Ozette out to the rugged seashore at Cape Alava.

I ditch my car at the Ozette ranger station and, from a rack of pamphlets, pick up the otter equivalent of a baseball card. It profiles the North American league's only two players--Enhydra lutris and Lontra canadensis--and right away it proves useful. Crossing the footbridge over the idle Ozette River, I flush a pair of otters resting below. They scamper into the water and streak away along the bottom, swimming facedown, paws pulling hard fore and aft, long, tapered tail streaming behind. I consult my card. Agile on land. Check. Swims facedown. Check. Paddles with webbed feet of roughly the same size. Check. Found in freshwater as well as salt. Check. This is Lontra canadensis, the river otter. Common as rain in the Pacific Northwest.

I walk on.

A boardwalk of split cedar slabs angles out to Cape Alava, through towering western hemlock and Sitka spruce, blue huckleberry, bunchberry, and salal. Three miles along it drops sharply. A silvery sea opens ahead and smacks me with its briny tang. Boardwalk gives way to red-brown duff; duff slopes down to gray-brown shingle and sand. Now cue the roar of the ocean. Cue the squeaky-hinge soprano of glaucous-winged gulls. Cue the raucous bellowing of a thousand male sea lions on the Bodelteh Islands offshore. I clamber aboard a titanic drift log and glass the kelp-ruffled slackwater.

Three adult otters loaf belly up in the kelp, riding the glittering sea. They cock their heads forward out of the water and, three feet astern, their flipperish, clown-shoe hind feet, too. Clutching their slender forepaws high on their chests, they look like pious little vicars lying in bathtubs a bit too small.

Checkmate. Here is Enhydra lutris, the sea otter, smallest of marine mammals and the most influential. This is the animal whose luxuriant fur drove Russian then British and American exploration of the Pacific Northwest, fueled the transformation of New England's economy, and made Alaska Russia's to sell. Whose appetite for shellfish shapes the kelp forest. Whose presence and then absence, extermination and then unlikely partial restoration to Pacific coastal habitats have given ecologists startling insight into the power of top carnivores. Whose tenuous survival may have stunning implications for the survival of wild species and habitats not only here on this remote coast but everywhere.


Though the sea otter is thought to have evolved some two million years ago, its story doesn't really pick up until 1742--the year the shipwrecked crew of explorer Vitus Bering's Russian expedition limped back to Kamchatka in an improvised boat. The crew had survived nine months on a barren island by eating the flesh of a winsome and gregarious little sea mammal that lived in the shallows and was clumsy as a seal ashore. When the men finally made their escape, they crammed their boat to the gunwales with its heavy pelts.

The sea otter is something of an arriviste among marine mammals. The only ocean-dwelling member of the mustelids--think saltwater weasel--it lacks blubber, the layer of specialized fat that insulates other marine mammals against the the heat-sucking properties of water. It makes do instead with its fur, the densest of any on earth. Sea otter fur packs an astounding 645,000 hairs to the square inch. Too heavy for women's wear, the fur was fashioned into hats and trim for men's robes. There was already a brisk Asian coastal trade in Bering's day. But the western Pacific held few sea otters. Bering's tattered crew brought news that a gold mine of sea otters lay just 200 miles offshore to the east. The fur rush was on.

By the time 1743 was out, legions of promyshlenniki--Siberian sable hunters--were crossing the Bering Sea in barely seaworthy boats. They soon enslaved Aleut hunters, with their nimble, skin-covered baidarka canoes, to do their sea otter hunting for them. During the next 90 years, promyshlenniki progressed slowly east across the arc of the Aleutian Islands and down the North American main, from one rocky, kelp-strewn inlet to the next, laying waste to otter and Aleut as they went.

British and American exploiters weren't far behind. In 1778 Captain Cook touched in at Vancouver Island (not yet so named), where his sailors did a little trading. When they put in at Macao months later, they were astonished to discover that Chinese buyers would pay handsomely for the bedraggled sea otter furs they'd been sleeping on. Within a decade Americans and Englishmen were trading for sea otter furs on the Northwest Coast; trading the furs for tea, silk, and spices in China; and selling those luxury goods in the West Indies, England, and New England. The influx of new wealth from this triangular trade transformed New England's fishing, whaling, and farming economy in the early 1800s. New England textile mills were built on sea otters' silky backs.

The commercial sea otter trade went bust by the mid-1800s. But a velvety sea otter pelt still brought big bucks. Here on Washington beaches, sharpshooters built 60-foot derricks from which they plinked at otters far out in the kelp, letting the incoming tide float the buoyant little bodies ashore.

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