Southern Sea Otters Nick Adler

Nick Adler

11/10/17

Southern Sea Otters (Enhydra lutris nereis): Super Cute Guardians of the Kelp Forest

Fig. 1 Smiling Sea Otter

Description: At first glance it can be hard to believe that this silly looking creature is absolutely essential to an entire ecosystem. But the Southern Sea Otter is just that, acting as a keystone species in Kelp Forests off the Pacific Coast of the U.S. The Sea Otter is the heaviest species in the Weasel family, though it is the smallest marine mammal native to North America. They have the densest coat of fur in the animal kingdom, which helps to insulate them against the cold ocean water as they no fat or blubber as many other marine mammals do. They influence the Kelp Forest primarily through their diet, which consists largely of Sea Urchins, which if left unchecked would devastate the kelp. Females typically give birth to one pup a year, which, despite being uncommon among carnivores, is “consistent with other marine mammals, except the Polar Bear” (Demaster 6).

                                               Fig. 2 Impact of Sea Otter on Kelp Forests

 Geographic and Population Changes: Sea Otters were nearly driven extinct in the 18^th and 19^th century due to hunting for their fur. Legal protection in 1911 from the International Fur Seal Treaty led to large population increases and recolonization of many areas in Alaska and Russia. Though the remnant population of Southern Sea Otters living off the coast of California appeared to increase in size throughout the 20^th century, the population did decline during two periods: from 1976-1984 and from 1995-1999. The population in 1976 was 1,789 individuals, while in 2002 the population was 2,139, showing a significant increase, which has remained stable in the years since. The most current population estimate from 2016 was over 3,090 individuals, which is very promising. The current range of the Southern Sea Otter runs from San Mateo County in the north to Santa Barbara County in the south. Despite some optimistic predictions, it seems unlikely that the Otters will reclaim their former range which ran along the entire Pacific coast of North America from Alaska to Baja California.

Fig. 3 Historical vs. Current Range of all subspecies

Fig. 4 Current Range of Southern Sea Otter

Listing and Threats: The Southern Sea Otter was listed as threatened in 1977 under the Endangered Species Act. The primary reasons for its listing were “reduced range and population size, vulnerability to oil spills, and oil spill risk from coastal tanker traffic” (Carswell). Though numerous other threats have been recognized since the otters were listed, such as pollution and bycatch, oil spills remain the number one threat. This is due in large part to the extraordinary mortality rate of Otters that are exposed to oil, which is estimated to be “no less than 50 percent”, though “this estimate is likely to be lower than actual losses” (Demaster 10). Exposure to recently introduced diseases is also a concern, though it has not yet proven to be a major issue for the Southern Sea Otters. Lastly, the slow rate of population growth means that any event which would negatively impact any populations would be particularly disastrous.

                                                 Fig. 5 Sea Otter affected by oil (SAD)

Recovery Plan: While the recovery plan for the Southern Sea Otter initially consisted largely of translocation programs, these have been largely abandoned after being deemed ineffective following multiple reviews. The recovery team believes that “range expansion of sea otters in California will occur more rapidly if the existing population is allowed to recover passively than it would under a recovery program that includes translocating sea otters” (Demaster 28). Therefore, the strategy has largely shifted to mitigating or eliminating the factors which are preventing natural population growth, which include disease, fishing bycatch, oil spills, contaminants, and intentional take of Sea Otters. The table below shows the tasks associated with each threat. In order for the Otter to be delisted, the population must be greater than 3,090 individuals for 3 years in a row, the first of which was 2016. “The ultimate goal of southern sea otter recovery is to reestablish ecological relationships in the ecosystems where sea otters and other nearshore species coevolved” (Carswell).

Table 1. Summary of Threats and Recommended Recovery Actions

LISTING FACTOR	THREAT	RECOVERY CRITERION	TASK NUMBERS
A	Restriction of range due to management zone	1	Evaluate translocation program in light of changed circumstances and determine whether one or more failure criteria have been met
C	Disease	1	Collect and analyze tissues for evidence of stress or disease; determine sources of disease agents and stress; minimize factors causing stress and disease
D	Incidental take in fishing gear	1	Evaluate causes of otter mortality; monitor incidental take in commercial fisheries; evaluate the effectiveness of fishing regulations for preventing sea otter take; evaluate incidental take in trap/pot fisheries; determine and take possible steps to reduce or eliminate sea otter mortality incidental to fisheries
E	Oil spills	1	Implement and monitor USCG vessel management plan; assess current risk of tanker accidents and other sources of oil spills, including off-shore oil platforms, pipelines, and marine terminals; implement an oil spill contingency plan that includes a sea otter response plan
E	Contaminants	1	Evaluate causes of otter mortality; analyze tissues from southern sea otters for environmental contaminants and archive tissues for future analysis; determine sources of environmental contaminants; determine contaminant levels in sea otter prey and habitat
E	Intentional take	1	Evaluate causes of otter mortality; minimize intentional take

What can we normal people do: The two biggest things the general public can do to aid the Southern Sea Otter is spread awareness about its endangered status and support legislation in California regulating or banning the extraction and transport of oil off the coast of California. The first is particularly important as many people have no idea that the Sea Otter is endangered and requires our help. The second is also very important because, as previously discussed, oil spills represent the gravest threat to Sea Otter populations, and these laws would also benefit many other species which don’t want to be covered in oil. Donating to any number of organizations and foundations which are dedicated to the preservation of Southern Sea Otters is of course also great, and I have included one such link below.

Other Resources:

Donate: http://www.seaotterfoundationtrust.org/adoptme/

If you haven’t seen the Sea Otters in Morro Bay, GO DO IT YA DINGUS!!!

Bibliography:

Fig. 1: Merideth, Cassidy. “11 Reasons Why Sea Otters Are The Cutest Animal Alive.” The Odyssey Online, 30 Oct. 2017, www.theodysseyonline.com/11-reasons-why-sea-otters-are-the-cutest-animal-alive.

Fig. 2: Media, Wharton. “Why Are Sea Otters Important? No Sea Otters. No Kelp Forests.”SEAOTTERS.COM – POWERED BY CUTENESS™, 23 May 2013, seaotters.com/tag/kelp-forests/.

Figs. 3 and 4: “Special Species Status: Southern (California) Sea Otter.” SIMoN -- Special Status Species: Southern Sea Otter (Enhydra Lutris Nereis), June 2006, sanctuarymonitoring.org/monterey/sections/specialSpecies/sea_otter.php.

Fig. 5: “Special Species Status: Southern (California) Sea Otter.” SIMoN -- Special Status Species: Southern Sea Otter (Enhydra Lutris Nereis), June 2006, sanctuarymonitoring.org/monterey/sections/specialSpecies/sea_otter.php.

United States, Congress, Demaster, Douglas, et al. “Final Revised Recovery Plan for the Southern Sea Otter.” Final Revised Recovery Plan for the Southern Sea Otter, 2003, pp. 1–179.

Carswell, Lilian. “Southern Sea Otter.” U.S. Fish and Wildlife Headquarters, www.fws.gov/ventura/endangered/species/info/sso.html.