Good news for California Sea Otters. And those of us who enjoy watching them.
After tabulating the results of its annual census of the Sea Otter population along the California coast, the U.S. Geologic Survey announced that it had recorded 3,272 otters,* “the first year,” since the organization began assessing Otter populations in 1982, “that the official index has exceeded 3,090.”
The importance of that record? Nearly hunted to extinction for their fur, California Sea Otters have struggled to return to historic population levels. To afford them the opportunity to survive as a species, the southern Sea Otter has enjoyed protection under the Endangered Species Act (ESA) since 1977. That protection—and the efforts of many marine biologists and otter enthusiasts—allowed the species to slowly recover from just 50 individuals (an historic low) to the current population of over 3,200 pups and adults. Should the Sea Otter population exceed 3,090 for three consecutive years, it would become a candidate for delisting from the ESA.
And enjoy acclaim as the newest near-extinction survival hero.
A few notes of caution, however. Though the otter population has risen as a whole, its numbers are weakest in the southern and northern extremes of its range. USGS researchers note that the lower numbers in these two areas is “consistent with an increase in shark bite mortality over the last 10 years,”
Yes, while on the hunt for seals, sharks have been erroneously grabbing, but not consuming, otters as they swim by. Realizing their error, the sharks simply release the otters. Unfortunately, most otters don’t survive these encounters. These shark attacks may explain not only why otter populations have concentrated along the central coast but also why they have not further extended their southern and northern ranges beyond Santa Barbara and Pigeon Point, respectively.
Why is it important that the Sea Otter extend its range? Species that become isolated in environmental enclaves can suffer higher losses from natural crises (such as red tides or prey population collapses) or unnatural disasters (such as oil spills, nuclear accidents, or presidential elections.**) And inbreeding can also make them more susceptible to pathogens and parasitic infection. Having both diverse populations and dispersed populations help species to survive long term.
Just look at us. Our success as a species can partly be attributed to the fact that we left Africa 50,000 to 80,000 years ago to explore and populate all but the most extreme environments on the planet. We’re both genetically diverse and spread wide. More resistant to infection. Less susceptible to earthquakes, tsunamis, and volcanic eruptions.
Should otters spread beyond the central coast and further increase in population, they will be less threatened by a single (or multiple) catastrophic event(s), and the environment will benefit, as well. A keystone species, the otter contributes to the success of the Kelp forest, one of the most important marine ecosystems on the planet. Kelp forests help to nurture and protect myriad marine creatures worldwide. And the Sea Otter contributes to the health of Kelp forests by countering the population growth of Sea Urchin, a marine herbivore that dines on Kelp. When Sea Otter populations plummet urchins can multiply wildly and devastate Kelp forests, dispersing the marine species that depend on them and reducing the likelihood of their survival.
Ironically, the growth of the sea otter population may be related to the decline of another keystone species. USGS researchers suggest that the sudden collapse of the seastar (or starfish) population along the Pacific coast may have contributed to an increase in the urchin population. Like sea otters, seastars dine on Sea Urchin. The wasting disease that decimated seastar populations all along the Pacific coast may have allowed Sea Urchins to proliferate. And that increase may have also allowed Sea Otters to thrive.
Nature abounds in such relationships and dependencies. That’s why it is so important for us to value and protect the diversity that remains.
* The figure actually results from a “3-year average of combined counts from the mainland range and San Nicolas Island.” The USGS uses averaging to “reduce the influence of anomalously high or low counts from any particular year.”
** Seriously, if you care at all about the future of our environment, the continued existence of our national parks, clean water, breathable air, or the vitality of our marine ecosystems, you might want to compare the environmental positions of the two candidates as outlined in “Where Clinton And Trump Stand On The Environment — In One Simple Graphic” and “Trump, Clinton on the Environment: a Handy Guide.” And you may want to consider what such diverse publications as Salon, The New York Times, Gizmodo, The Washington Post, and The Street have conveyed about the potential effect one of the two candidates may have on the environment if elected.
You can learn more about the Sea Otter’s population growth, and other related topics, in the following sources:
• California Sea Otter (Enhydra lutris nereis) Census Results, Spring 2016
• California Sea Otter Population Reaches Record High Number
• California’s Sea Otter Population Makes a Comeback
• Fact Sheet: Sea Otter
• Sea Otter: Enhydra lutris [National Geographic]
• Southern Sea Otter
• Sea otter [Wikipedia]
• The Otter Project
• What Is a Kelp Forest?
• Giant Kelp
• Kelp forest [Wikipedia]
• Photo Gallery: Sea Urchins
• Sea urchin [Wikipedia]
• Sea Urchins