The Southern Sea Otter

Courtesy of Monterey Bay Aquarium (montereybayaquarium.org)

The Southern Sea Otter, also commonly known as the California Sea Otter, belongs to the mustelidea family, along with weasels, skunks, and river otters. Sea otters are the only exclusive marine mammal to belong to this family. Southern Sea Otters are the smallest marine mammal in North America. Unlike other marine mammals, the Southern Sea Otter does not have a layer of blubber to stay warm; instead, they have dense fur. In fact, Southern Sea Otters have the world’s densest fur. Their two-layer fur consists of a million hairs per square-inch (Monterey Bay Aquarium)! That’s a lot of hair! But this fur also requires maintenance; otters spend many hours a day grooming and cleaning their fur, and this helps to keep their coat waterproof. Southern Sea Otters can grow up to four feet long and weigh up to 50 pounds (for females) and 70 pounds (for males) (Monterey Bay Aquarium). Sea otters usually give birth to one pup, but can give birth to twins, and they usually carry their pups for about six to eight months before giving birth (Defenders). 

The Southern Sea Otter is often found floating and foraging for food among the kelp forests. Their diet consists of crabs, sea snails, urchins, clams, mussels, and other small invertebrates. The Southern Sea Otter plays a crucial role in maintaining the health of the kelp forests. Several of the animals that they eat tend to pray on the kelp forests, so the otters help the kelp to thrive. As a result of saving this kelp, they help to provide a healthy community, as well as maintaining the habitat for other animals that call the kelp forests home and rely on the kelp forests for cover or food. 

Southern Sea Otters used to call the range from the Pacific Northwest to Baja California home, but their range has since decreased; their current range runs from San Mateo County to Santa Barbara County (Monterey Bay Aquarium). The hunting of sea otters for their fur nearly drove the sea otters to extinction by the 1920s (Monterey Bay Aquarium). By 1911, there was only a small group of about fifty otters left near the coast off of Big Sur and they were put under the protection of the North Pacific Fur Seal Treaty (Monterey Bay Aquarium). In 1977, the Southern Sea Otter was listed under the Endangered Species Act. Since then, there has been dedication in increasing the sea otter population. Today, it is estimated that their population is approximately 2,150 individuals here in California (Recovery Plan). 

(were.usgs.gov)
Area highlighted in yellow off of California is the Southern Sea Otter's current range. 

The Southern Sea Otter is currently listed as threatened. They were first listed in 1977, and their recovery plan was approved in 1982. However, additions continue to be made to their recovery plan, with the most recent additions being made in 2003. While their population has slowly recovered, their population still remains far below original population numbers. The primary portion of their range, which is between Monterey Bay and just south of the coast off of Big Sur, can’t support higher populations of sea otters, so in order to keep their population growing, they must expand their range to find new areas with an abundance of food (Monterey Bay Aquarium). 

While the primary reason for their listing under the Endangered Species Act was due to intensive hunting, the Southern Sea Otter faces many new challenges today that prevent their populations from steadily increasing. One major risk that the Southern Sea Otter faces is the potential for an oil spill (Monterey Bay Aquarium). When sea otters get oil on their fur, the oils causes it to mat, which then prevents the otter from being able to insulate its body. Without the protection of their fur from the icy, cold waters of the Pacific Ocean, the sea otter can quickly die from hypothermia (Defenders). The oil can also cause kidney and liver failure, as well as damage to their lungs and eyes (Defenders). Southern Sea Otters are highly susceptible to being caught in fishermen’s nets. Sea otters like to eat crabs and other shellfish, and as a result, they tend to hang out in areas with high concentrations of these animals. Sadly, crabs and other shellfish are also foods that humans like, so when fishermen go out to catch these shellfish, the otters get caught in the nets and can drown or be seriously harmed (Defenders). Sometimes fishermen also see sea otters as a threat to their economic gain, and will intentionally harm the sea otters (Defenders). Fortunately, sea otter deaths due to human conflict have been decreasing as a result of the increased regulation of fishing nets under the Endangered Species Act. Lastly, habitat degradation is affecting the Southern Sea Otter’s ability to increase their populations. When pollution runs from the land into the ocean, it can contaminate the sea otter’s habitat, and jeopardize their food sources (Defenders). Southern Sea Otters are often contaminated with pollutants and disease-bearing parasites. These disease-bearing parasites cause up to 40% of sea otter deaths (Defenders). 

Courtesy of Monterey Bay Aquarium (montereybayaquarium.org)

The objective of the recovery plan for the Southern Sea Otter is manage human activities that could potentially jeopardize the existence of the Southern Sea Otter, or damage or destroy their habitat. According to the recovery plan, in order for the Southern Sea Otter to be removed from its endangered listing, their population would need to reach at least 3,900 individuals. There are several actions to be taken outlined in the recovery plan. First, one objective is to “monitor the Southern Sea Otter’s demographics and life history parameters to determine population size, rate of change, and distribution” (Recovery Plan). Next, the objective is to evaluate the habitat for changes in “types, abundances, distribution, and use, and changes in its estimated carrying capacity” (Recovery Plan). This includes feeding, breeding, birth area, etc. Then, the objective is to protect the Southern Sea Otter population and reduce, or possibly eliminate, any potential limiting factors to their increase in population due to human activities, such as some of the activities that were previously discussed. Afterwards, research must be conducted to understand what exactly is limiting the growth rate of the Southern Sea Otter population. From these findings, the recovery goals will be able to be refined and “management actions can be identified and implemented” (Recovery Plan). Lastly, the translocation program will be evaluated for “failure criteria” and will be determined if the experimental population at San Nicolas Island met any of the failure criteria (Recovery Plan). This will help to determine if sea otter containment may jeopardize the population or hinder its recovery. The colony at San Nicolas Island contained approximately twenty seven individuals, including pups, and even though there were approximately seventy births at this location between 1987 and 2002, the population remained very low (Recovery Plan). The total estimated cost for this recovery plan over the next twenty years is $10,219,700 (Recovery Plan). Since the Southern Sea Otter population hasn’t been increasing at a steady rate, it is not possible to predict when the Southern Sea Otter will actually be considered recovered. However, even if the population grew at a steady rate of 5% per year, it would take at least ten years before it could reach delisting criteria. 

In order to help continue the fight to save the Southern Sea Otter, you should become a member of and donate to the Monterey Bay Aquarium, who is active in the research of the Southern Sea Otter. The Monterey Bay Aquarium’s Sea Otter Program has been studying the threatened Southern Sea Otter since 1984 to understand the threats to their population and promote their recovery (Monterey Bay Aquarium). The Monterey Bay Aquarium also rescues, treats and releases injured otters; they have a surrogate mother program to raise and release stranded pups as well (Monterey Bay Aquarium). The Monterey Bay Aquarium also helps find homes for otters that cannot return to the wild (Monterey Bay Aquarium). Their research is helping to make a difference in the Southern Sea Otter’s population, and by contributing to the Monterey Bay Aquarium, you can assist in keeping their research going so we can find a way to bring the Southern Sea Otter’s population back to their previous levels and delist them from the Endangered Species List. 

You can watch the Southern Sea Otters of the Monterey Bay Aquarium here on their Live Web Cam: http://www.montereybayaquarium.org/animals-and-experiences/live-web-cams/sea-otter-cam

Sources: 

"Final Revised Recovery Plan for the Southern Sea Otter." U.S. Fish and Wildlife Service. U.S. Fish and Wildlife Service Region 1, 24 Feb. 2003. Web. 8 Nov. 2015.

"The Sea Otter Exhibit." Sea Otters at the Monterey Bay Aquarium. Web. 8 Nov. 2015.

"Southern Sea Otters." Southern Sea Otter Priority at the Monterey Bay Aquarium. Web. 8 Nov. 2015.

"Southern Sea Otter." (Kelp Forest, Marine Mammals, Enhydra Ultras Nereis) at the Monterey Bay Aquarium. Web. 8 Nov. 2015.

"Threats to Sea Otters." Defenders of Wildlife. 19 Mar. 2012. Web. 8 Nov. 2015.

"Basic Facts about Sea Otters." Defenders of Wildlife. 19 Mar. 2012. Web. 8 Nov. 2015.



"The Southern Sea Otter": Emily Veith