Michael: For the fur of an animal

Here on the West Coast, there is hardly a more emblematic and likeable animal than the sea otter (Enhydra lutris). Whether it’s for their cuteness or their important ecological role as keystone predators, we like having them around. But it hasn’t always been that way. For most of recent history, sea otters were valued for one thing and one thing only: their fur. In fact, the trade in otter furs was so profitable and so intense that it almost drove the species to extinction.

 Image: https://www.nps.gov/glba/blogs/otters-on-ice.htm

Image: https://www.nps.gov/glba/blogs/otters-on-ice.htm

Instead of an insulating layer of blubber, as most marine mammals have, sea otters are equipped with a coat of thick, dense fur—a marvelous adaptation for staying warm, but an irresistible prize for fur traders (Kenyon 1969). Indigenous people had long hunted otters for their pelts and for food (Reidman and Estes 1990), but it wasn’t until the Russians arrived in North America in 1741 and began making their way down the Pacific Coast—eventually reaching as far south as Fort Ross, in Sonoma County—that widespread exploitation of the otters took hold. Once news spread of their luxurious coats, and of the amazingly high prices they fetched on the Chinese market (Ogden 1941), other nations were quick to capitalize on the trade, including Spain, Britain, and the newly formed United States. Hunting of sea otters continued unregulated until 1911, when the worldwide population had been reduced from over 150,000 individuals to less than 2,000. That year, they were protected under the International Fur Seal Treaty (Reidman and Estes 1990).

 A man standing next to a sea otter pelt in the Aleutian islands.  Photo taken in 1892, from NOAA’s  Historic Fisheries Collection .  Public link:  https://commons.wikimedia.org/wiki/File:Skins_of_sea_otters_1892_right.jpg

A man standing next to a sea otter pelt in the Aleutian islands.

Photo taken in 1892, from NOAA’s Historic Fisheries Collection.

Public link: https://commons.wikimedia.org/wiki/File:Skins_of_sea_otters_1892_right.jpg

Since then, the species has begun to recover. They’re still a long ways off from inhabiting the full extent of their original range, which stretched from northern Japan to Baja California, but their numbers are now locally increasing in many regions. Here in California, sea otters—specifically the southern subspecies, Enhydra lutris nereis—were thought extinct until a remnant colony of around 50 individuals was discovered in 1938 near Bixby Creek in Big Sur (Gagne et al. 2018). Remarkably, it is from this single colony that the entire California population has since rebounded, almost to the point of being de-listed as an endangered species (Tinker and Hatfield 2016).

This comeback has positive consequences not only for the otter population as a whole, but for the health of California’s coastal ecosystems. By eating urchins, which graze on kelp, otters allow kelp forests to thrive, and these forests in turn support the biologically rich fisheries and food webs that characterize the West Coast. When the otters disappeared, as they did from hunting prior to 1911—or from killer whale predation, as in the case of the Aleutian island “urchin barrens” of the 1990s (Estes et al. 1998)—the kelp forests suffered, decimated by overly populous urchins. As otters have returned to parts of their former range, so has the kelp (e.g., Lance, Richardson, and Allen 2004).

While the long-term trend for sea otters is encouraging, there are some troubling indicators. California’s otter population is growing slowly, and has struggled to expand its range north or south of a core region centered on Monterey Bay. Reintroduction efforts have met with mixed success, and have been hindered by questions over habitat suitability and regional population differences that continue to spark debate in the academic community (Kone 2018). Washington’s Olympic Peninsula, for instance, is now home to a growing otter population that was translocated from Alaska in the late 1960s (Lance, Richardson, and Allen 2004), but similar efforts in the 1970s off of Oregon failed (Jameson et al. 1982). In southern California, with the exception of an experimentally established colony on San Nicolas Island, southward sea otter expansion was actually blocked by the US Fish and Wildlife Service in the hope of minimizing conflict with commercial fisheries. This “no-otter” mitigation zone ended in 2012, but the species’ expansion in the region is expected to remain episodic (Lafferty and Tinker 2014).

In additional to these logistical challenges, sea otters are also vulnerable to the spread of disease. The parasite Toxoplasmosis gondii, which infects otters via contact with feline feces—from wild animals as well as pets—has recently been suggested as a cause of their slow recovery (Lafferty 2015), and is particularly worrisome in light of the otters’ low genetic diversity and therefore low disease resistance (Gagne et al. 2018). A mysterious rise in great white shark attacks has also been documented at the peripheries of the otters’ California range, slowing the species’ expansion even more (Tinker et al. 2016).

All of these problems, from translocation failures to predation, are active areas of scientific research. But to fully recover the sea otter, we must do more than simply address these issues. We must continue to tell the story of the otters’ past: their ruthless exploitation, their surprising rediscovery, their recent comeback. Only when we are mindful of this historical context can we properly address the species’ current challenges, and ensure we never again lose sight of what really matters—not the fur, but the living, breathing sea otter.

Michael Montgomery is a third-year student at UC Davis. He is majoring in Marine and Coastal Science, with planned minors in History and Professional Writing, and is considering a career in science writing.

Learn more on the student research blog!

Works Cited

Estes, JA, MT Tinker, TM Williams, and DF Doak. 1998. “Killer whale predation on sea otters

linking oceanic and nearshore ecosystems.” Science, 282:473-476.

http://science.sciencemag.org/content/282/5388/473

Gagne, RB, MT Tinker, KD Gustafson, K Ralls, S Larson, LM Tarjan, MA Miller, and HB

Ernest. 2018. “Measures of effective population size in sea otters reveal special considerations for wide-ranging species.” Evolutionary Applications, 1-12.   https://doi.org/10.1111/eva.12642

Jameson, RT, KW Kenyon, AM Johnson, and HM Wight. 1982. “History and Status ofTranslocated Sea Otter Populations in North America.” Wildlife Society Bulletin,

10(2):100-107. http://www.jstor.org/stable/3781726

Kenyon, KW. 1969. The Sea Otter in the Eastern Pacific Ocean. Dover, 352 pp.

Kone, D. 2018. “Oregon sea otter reintroduction: opinions, perspectives, and theories.” Geospatial Ecology of Marine Megafauna Laboratory, Oregon State University.

http://blogs.oregonstate.edu/gemmlab/2018/05/28/oregon-sea-otter-reintroduction-

opinions-perspectives-theories/

 Lafferty, KD. 2015. “Sea otter health: challenging a pet hypothesis.” International Journal for Parasitology: Parasites and Wildlife, 4(3):291-294. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4491668/

Lafferty, KD, and MT Tinker. 2014. “Sea Otters are recolonizing southern California in fits and starts.” Ecosphere, 5(5):50. https://doi.org/10.1890/ES13-00394.1

Lance, MM, SA Richardson, and HL Allen. 2004. “Washington State Recovery Plan for the Sea Otter.” Washington Department of Fish and Wildlife, 91 pp.

https://wdfw.wa.gov/publications/00314/wdfw00314.pdf

Ogden, A. 1941. The California Sea Otter Trade, 1784-1848. University of California Press, 251 pp.

Reidman, ML, and JA Estes. 1990. “The Sea Otter (Enhydra lutris): Behavior, Ecology, and Natural History.” US Fish and Wildlife Service, Biological Report 90(14): 126 pp.

https://www.fort.usgs.gov/sites/default/files/products/publications/2183/2183.pdf

Tinker, MT, and BB Hatfield. 2016. “California Sea Otter (Enhydra lutris nereis) Census Results, Spring 2016.” USGS Data Series 1018, 10 pp. http://dx.doi.org/10.3133/ds1018

Tinker, MT, BB Hatfield, MD Harris, and JA Ames. 2016. “Dramatic increase in sea otter mortality from white sharks in California.” Marine Mammal Science, 32(1):309-326.

https://doi.org/10.1111/mms.12261