Group 9: Southern sea otter

Southern Sea Otter

Enhydra lutris nereis

Alyssa Slattery

https://seaotters.com/sea-otters/

Description and Ecology

Aside from the obviously adorable face of the Southern Sea Otter, there are many characteristics that make these critters unique. Simultaneously the largest Mustelidae and smallest marine mammal, they weigh in around 45 pounds for females and 65 pounds for males. The Southern Sea Otter is about four feet long, with a tail making up less than one third of the body. Their famous, luxurious fur is a dark brown to reddish brown color, accompanied by a dense underfur that provides warmth from trapped air. This fur is essential for survival due to their lack blubber and small amounts of fat.

metro.co.uk

While the otters' back limbs are used for their agile swimming, the front paws are used for grooming and eating. Nearly 20-50% of their day is spent foraging because of their high metabolism. They eat 25% of their body mass daily. So what do otters eat? With their dietary diversity, otters can consume a variety of invertebrates but are most famously known for their consumption of kelp-associated fish and sea urchins. As a keystone species, the Southern Sea Otter's abundance has a great impact on other species in the ecosystem--one of the critical reasons we need to conserve these little guys. Their presence has an indirect positive effect on kelp forests which serve as habitats, reduce coastal erosion, and act as a carbon sink.

Sexual maturity is reached after three years for females, and five years for males. They have about one pup per year typically in-between February and April, but can reproduce anytime during the year. The mothers care for their pups for six months and are extra vulnerable to stressors during this time. Southern Sea Otter remain prominent creatures, although can be easily put in danger due to a variety of stressors.

Geographic and Population Changes

The Southern Sea Otter thrives along a rocky shoreline with nearby kelp beds. Originally found along the North Pacific Rim from Japan to all the way to Mexico, their range has dramatically been reduced in recent years. The southern subspecies used to range from parts of Oregon to Baja California, although has been reduced to 13% of that area--now only recorded from San Mateo County to San Diego County.

http://sanctuarymonitoring.org/monterey/sections/specialSpecies/sea_otter.php

During the 18th and 19th centuries, otters were almost hunted to extinction for their precious fur. Fortunately, in 1911, the International Fur Seal Treaty was passed in order to legally protect them. The surviving 50 otters along the coast of Big Sur soon became the ancestors for all future California otters and nutured a growing population into the 1970's.

https://soundwaves.usgs.gov/2002/07/

Just when the future was looking bright, increased incidents of mortality due to entanglement in fishing gear led to a population decline in the late 1970's and into the 1980's. State regulations worked to limit these fishing related mortalities, and in turn, increased the population to over 2000 otters in the 1990's. Into the 2000's, populations seem to stop growing, but this time from different threats: shark attacks, disease, starvation, habitat degradation etc. For many years now, the Southern Sea Otter has been been reduced to a small range and continues to see unstable population shifts due to a variety of dangers.

Listing Date and Type of Listing

From the obvious hardships these precious creatures have faced, the Southern Sea Otter is declared threatened under the Endangered Species Act of 1973 and depleted under the Marine Mammal Protection Act of 1972.

Cause of listing and Main threats to the Southern Sea Otter

According to the U.S. Fish and Wildlife Service, the Southern Sea Otter is listed as threatened due to their dramatically reduced range, lack of population growth, and susceptibility to extreme damage from potential oil spills.

https://www.treehugger.com

Whether it be getting caught in fish netting or pollution, human actions have huge effects on otters. Oil hinders the fur's insulation, leading to hypothermia and death--not to mention the habitat degradation. If an oil spill were to occur off the coast of California, the otter population would be in great danger due to the catostrphic damage. Obvious hunting or harassment interrupts their chance for survival as well.

Although, not all threats are human-related: Turns out 40% of deaths are disease related, and more and more otters are being impacted by the infestation of acanthocephalan parasites. Their restricted range leads to limited resources, which tends keep populations from increasing as well. While humans can sometimes step in to lessen these stressors, current lack of growing populations are a puzzle scientists struggle to piece together. There are so many factors that target the already vulnerable Southern Sea Otter, making it hard for prevention and an ultimately strong recovery.

Recovery Plan

https://giphy.com/gifs/otters-dQ234KLlgOgWA

The Final and Revised Recovery Plan was published Februrary 2, 2003 in efforts to get the Southern Sea Otter delisted--requiring that the population grows larger than 3,090. While they would delisted, researchers inquire that the population wouldn't be actually sustainable along the California coast until it reaches about 8,400.

Since 2003, the plan has been working to limit human impacts on the otter to increase their number and range. Although the plan has more detailed inter-workings, the overall recovery actions emphasize minimizing potential for human damage. Putting more research into disease causing factors, implementing stricter fishing regulations, evaluating translocation programs, enforcing the ban on intentional take, locating the sources of environmental contaminants, and regulating methods used by oil-carrying are all ways we hope to conserve these top predators. By monitoring demographics and habitats, scientists can analyze the effects of their efforts.

What can you do?

1. Adopt a Sea Otter: Make a donation to the World Wide Fund for Nature (WWF) or the California Sea Otter Fund to go towards conservation efforts

2. Report stranded otters: If you happen to live along the coast, keep a close eye out for a potential opportunity to assist an otter by contacting professionals

http://www.montereybayaquarium.org/conservation-and-science/our-priorities/thriving-ocean-wildlife/southern-sea-otters#report-a-stranded-otter

3. Follow the 3 R's: Reducing, reusing, and recycling can help prevent possible contaminants and pollutants from entering the otters' habitat

4. Eat less fish: By not supporting the fish industry, less otters are likely to be entangled during fishing activities

5. Volunteer: Spend a couple hours on a weekend at your local beach to clean up and preserve the little habitat the otters' have left

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