Wildlife Success Stories: Sea Otters

“One person started a movement that saved otters and most other marine mammals from extinction”

One of my all-time favorite experiences as a marine biologist was kayaking with sea otters in Monterey Bay. Although several laws prohibit going near sea otters, otters may come to you if they feel bold and curious—and they have even been observed climbing on kayaks to preen and eat sea urchins. What made my experience so memorable was otter moms all around me were wrapping their pups in floating kelp fronds so they could dive for urchins, molluscs, and crustaceans to feed themselves and their babies.

A mother sea otter with twin pups in fronds of the kelp Macrocystis pyrifera. Photo by Mike Baird.

Watching these cuddly little balls of fur swaddled in kelp was just one of the coolest ocean wildlife encounters I’ve ever had. It’s what makes my job so much fun and why I am so passionate about saving ocean wildlife. Sea otters were hunted to the brink of extinction over a century ago, but citizens, scientists, and politicians worked together for many decades to bring about one of the greatest wildlife success stories in history.

What are sea otters and where are they found?

Otters are found in saltwater (ocean) or freshwater (rivers). There are two kinds of saltwater otters: marine otters whose range is along the Pacific Coast of South America, and sea otters whose range extends from Japan to Mexico along the North Pacific Rim (coasts of Japan, Russia, Alaska, Canada, United States, and Mexico). Even though marine and sea mean essentially the same thing, in otters these terms differentiate them. For this blog, we will be talking about sea otters along the North Pacific Rim.

Sea otters (Genus: Enhydra species: lutris) are the heaviest members of the weasel family that includes weasels, badgers, and minks, but the smallest species of marine mammal that includes whales, dolphins, porpoise, manatees, dugongs, seals, sea lions, and polar bears (that’s right, polar bears are considered marine mammals because they spend a lot of time in and on the ocean).

Two sea otters playing among the kelp Nereocystis luetkeana. Photo by Kieran Wood.

There are three subspecies of Enhydra lutris with distinct geographical distributions along the North Pacific Rim:

Enhydra lutris lutris, the Asian sea otter, ranges from the Kuril Islands north of Japan to Russia’s Commander Islands in the western Pacific Ocean.

Enhydra lutris kenyoni, the northern sea otter, ranges from Alaska’s Aleutian Islands in the northern Pacific Ocean to Oregon in the eastern Pacific Ocean.

Enhydra lutris nereis, the southern sea otter, ranges from central to southern California in the eastern Pacific Ocean. The southern sea otter is sometimes referred to as the California sea otter.

Sea otters are a keystone species

A keystone species is a crucial member of its ecosystem critical to the survival of other species. Without its keystone species, an ecosystem undergoes a significant transformation that most experts consider to be negative because it decreases the biodiversity of species within the ecosystem, harming the ecosystem as a whole.

Sea otters are a keystone species in kelp forest ecosystems, one of the most diverse and productive ocean ecosystems in the world because of the protection and foraging opportunities provided by the forest. Sea otters control the numbers of their prey in kelp forest ecosystems by eating them. Their prey—sea urchins, molluscs, and crustaceans—eat kelp at the base of the ecosystem. Without sea otters, prey populations become too large, overwhelming the kelp and harming the ecosystem. New research suggests sea otters may also play a key role in managing carbon dioxide levels in the oceans and atmosphere by protecting kelp forests.

Sea otters were hunted close to extinction for their fur

Most marine mammals have a thick layer of fat, or blubber, that serves as insulation against frigid ocean waters. But the sea otter’s primary form of insulation is a thick fur coat, the densest in the animal kingdom. Sea otter fur has a density between 120,000 to 140,000 hairs per square centimeter (hairs/cm2). By comparison, Arctic foxes and chinchillas both have between 16,000 to 20,000 hairs/cm2, house cats 800-1600 hairs/cm2, dogs 300-600 hairs/cm2, and the densest human hair comes in at just under 200 hairs/cm2.

Sea otter fur has two layers, an insulating inner layer for warmth and a waterproof outer layer to minimize ocean water removing that warmth. These two features—insulation for warmth and waterproof—made sea otter fur one of the most valuable furs to trade during a period of extensive hunting and trading from Russia to Alaska to California. A single sea otter pelt could fetch up to $100 (about $3000 today). Between 1741 and 1911, hunting decimated populations of sea otters from a peak estimated at around 300,000 otters to fewer than 2,000.

By 1911, what had once been a continuous population of sea otters along the entire coast of the North Pacific Rim had dwindled to just 13 discontinuous remnant groups. The only surviving group south of Alaska was discovered in 1915 off Point Sur, California. There were about 50 California Sea otters in this group and they are the genetic ancestors of all Enhydra lutris nereis today.

One person started a movement that saved otters and most other marine mammals from extinction

We often wonder what one person can really do to save ocean wildlife, but movements often start with the vision and action of a single individual. In the case of sea otters (and most other marine mammals), that person was Henry Wood Elliott. Elliott worked for the US Treasury Department in the North Pacific fur seal trade in the late 1800’s and early 1900’s. He came to realize that populations of marine mammal species hunted for fur were being decimated.

In 1905, Elliot persuaded the US Secretary of State to co-author an international treaty placing a five year moratorium on hunting to allow decimated herds to recover. The North Pacific Fur Seal Treaty of 1911 was ratified by Japan, Russia, Great Britain (for Canada), and the United States. It was the first international treaty protecting endangered species of marine mammals, establishing a clear precedent for future national and international laws and treaties, including the Fur Seal Act of 1966, the Marine Mammal Protection Act of 1972, the Marine Protection, Research and Sanctuaries Act of 1972 (which established the National Marine Sanctuary Program), and the Endangered Species Act of 1973. Sea otters were listed as a threatened species off the California coast in 1977.

As a direct result of Elliott’s treaty in 1911 and all subsequent treaties and laws protecting marine mammals and their habitats, sea otters have been able to make a partial recovery to around 150,000 individuals (about half their peak number) scattered throughout their historic range.

Factors limiting complete sea otter recovery to historic numbers and range include disease, predation, resource limitation, pollution, human activities, and genetics.

How you can make a difference

1) Keep plastics and other marine debris out of the ocean.

2) Don’t flush kitty litter down the toilet. Kitty litter contains harmful microbes that kill sea otters when wastewater makes it to the ocean.

3) Respect laws that protect sea otters, including laws for boaters, paddlers, and everyone else visiting sea otter habitats.

4) California residents can contribute to the California Sea Otter Voluntary Tax Contribution Fund on their state tax return. When preparing your California Resident Income Tax Return, go to the Contributions section on side 4 of Form 540 or side 3 of Form 540-2EZ. Enter the amount of money you wish to donate in the box next to code 410.

5) Support scientific research, conservation, and legislative efforts to protect sea otters, marine mammals, and marine sanctuaries. Environmental protections were significantly scaled back from 2017-2020, so let your federal and state representatives know that you want those protections restored, strengthened, and new protections passed to help sea otters fully recover.

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