Happy 40th Endangered Species Act!

sea otter mom and pup

On December 28, 1973, the Endangered Species Act (ESA) was signed into law.  Four years later, in 1977, California’s southern sea otter (Enhydra lutris nereis) was listed under the ESA as a threatened species – a conservation status which remains to this day. With the current population estimated at only 2,900 animals, sea otters still have a long road to recovery, but the ESA’s strong legal protections have been instrumental in the fight to save the species from extinction.

Why Are Sea Otters Important?
Sea otters are an iconic species, representing the beauty and diversity of marine life found along California’s coastline.  They’re also considered a keystone species because of their critical importance to the health and stability of the nearshore marine ecosystem.  They eat sea urchins and other invertebrates that graze on giant kelp.  Without sea otters, these grazing animals can destroy kelp forests and consequently the wide diversity of animals that depend upon kelp habitat for survival.  Additionally, kelp forests protect coastlines from storm surge and absorb vast amounts of harmful carbon dioxide from the atmosphere.  Sea otters are also considered a sentinel species because their health reflects that of California’s coastal waters.

Why Aren’t They Recovering?
Recent studies have shown that high mortality rates among prime-aged adult animals are the underlying cause for the population’s stagnant growth and disturbingly low numbers.  Scientists attribute up to 40 percent of southern sea otter mortality to infectious diseases alone, many of which are known to have anthropogenic (human) causes and land-sea linkages.  White shark attacks, pathogens and parasites, food limitation, nutritional deficiencies, habitat degradation, coastal pollutants and contaminant exposure are among many of the contributing factors threatening the recovery of the species.  And the risk of a major oil spill remains a serious threat.

What’s Being Done About It?
Researchers are working hard to gain a better understanding of what’s threatening sea otters so we can find ways to help them recover.  Determining precisely how all of the factors driving elevated mortality are impacting the overall health of the southern sea otter population and the nearshore marine ecosystem on which they and other species depend is critical.  The goal is development and implementation of effective, long-term management and mitigation strategies that can lead to the recovery of the species.


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Seaotters.com is dedicated to raising awareness about California's threatened sea otters and the role research plays in the species recovery and conservation. It's a collaboration of the Monterey Bay Aquarium, U.C. Santa Cruz, U.C. Davis, U.S. Geological Survey, U.S. Fish & Wildlife Service, California Department of Fish and Wildlife, among others. Seaotters.com is also home of the world's first HD live stream of southern sea otters in the wild.