The Sea Otter's Role in the Ecosystem
Sea otters are the textbook example of a "keystone" carnivore. Sea otters dramatically change the structure and complexity of their ecological community. Sea otters increase diversity and productivity.
By consuming 'grazers,' the animals that feed on kelp, the sea otter enhances kelp production.
California kelp forests are the most diverse ecosystem of the temperate latitudes on earth.
California kelp forests have some of the highest primary productivity rates (conversion of sunlight to living material) of any naturally occurring ecosystem on earth.
Sea otters eat between 20-35% of their own body weight daily. Because of their voracious appetite, they are occasionally accused of driving their prey species into decline by fishermen who compete for the same prey species. In fact, sea otters do not cause the local extinction of species. They do however alter the distribution of prey species, which adapt to a predator-prey relationship. Abalone numbers are often high within the sea otters range. However, the abalones are restricted to deep crevices, out of reach of otter and human harvesters. It is a widely accepted ecological concept that the more diverse and complex an ecosystem, the more stable it is.
Some researchers hypothesize that sea otters and their voracious appetites have played an important role in shaping the natural history of the California coastline and the Pacific Rim. Rather than driving their extinction, sea otters may be responsible for the relatively large size of abalones in California, in comparison with other parts of the world.
Sea otters are an indicator of the health of the nearshore marine ecosystem. An indicator species is an organism that is relatively sedentary and tends to bio-magnify and/or be sensitive to contaminants.
The sea otter tends to be relatively sedentary in comparison to other marine mammals.
The sea otter eats a wide variety of foods, including but not limited to ablone, sea urchin, crabs and lobster.
The sea otter is closely related to mink, a carnivore with established sensitivities to contaminants.
Incidence of disease in sea otters is correlated with the contaminants tributyltin (used as an anti-fouling agent in boat paint) and DDT (a banned pesticide). High levels of other contaminants, such as PCB, are also found in sea otter tissues.
The sea otter is an umbrella species. Protections given to the otter tend to 'shelter' and offer benefits to other species, habitats, and ecosystems.
Sea otters have the notoriety of an 'Endangered Species'. They are listed as threatened under the Endangered Species Act, and as depleted under the Marine Mammal Protection Act.
Sea otters have broad appeal to a worldwide audience.
Sea otters have proven to be an effective tool in enacting ecosystem wide protections including:
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