The Southern Sea Otter is Otterly Invaluable
The Southern Sea Otter (Enhydra lutris nereis) is a beloved, iconic species of Monterey Bay. Beyond the sea otter’s undeniable charm, the southern sea otter is a keystone species. Ecologist Robert Paine coined the term in the 1960s on a trip to Mukkaw Bay in the Pacific Northwest, observing the cascading negative impacts to a rocky intertidal ecosystem if its top predator—a starfish—was removed. Paine concluded the starfish was “the keystone of the community’s structure, and the integrity of the community and its unaltered persistence through time.” Here in California, southern sea otters are the keystone species in coastal ecosystems. The otters prey on sea urchins—a voracious consumer of kelp. By keeping the sea urchin populations at bay, sea otters maintain the health of coastal kelp forests. The presence of sea otters even serves as an indicator of health for the entire ecosystem.
Southern sea otters have been listed as threatened under the Endangered Species Act since 1977, having been historically decimated by the fur trade. As a keystone species in California’s coastal habitats, defending the southern sea otter is an investment in our local communities. Beneficial ripple effects of a recovered southern sea otter population include healthier kelp forests, abundant fisheries, and increased ecotourism - valued at $53M annually. In the near term, Santa Barbara and Ventura Counties alone could incur income gains of $1.5-8.2M each year with an added 62-326 direct tourism related jobs if sea otter populations returned.
Most important is the sea otter’s role in the survival of California’s underwater forests. Kelp serves as abundant habitat for rocky subtidal ecosystems that support thousands of diverse wildlife species, while providing economic support for coastal communities. Kelp is uniquely able to attach to submerged rocks, reducing ocean currents within its forest environment to provide a calm sanctuary for fish, invertebrates, and marine mammals. The calmer waters provided by blooming kelp forests also prevent coastal erosion, increase the ability for kayakers, surfers and the-like to recreate, and enable commercial fisheries to operate. Perhaps most importantly, these submerged forests operate as massive carbon sinks—absorbing CO2, to combat ocean acidification. It is estimated that farming kelp in just 3.8% of California’s federal waters could offset the state’s entire load of agricultural emissions.
But the kelp needs our help. A 2014 El Niño marine heat wave wiped out over 90% of California’s north coast kelp. Simultaneously, a breakout of sea star wasting disease led to a boom in purple sea urchins due to the lack of predators. Yet, in Monterey Bay, where the sea otter’s population is at its strongest, small patches of kelp forests persevered where the small, yet mighty, marine mammal consumed enough urchins to prevent forest devastation. Not only would a loss in sea otters contribute to a loss in kelp forests, but sea otters rely on these rocky, kelp-dominated habitats, where their populations tend to be most stable year to year. Treasured across the state, the value of these kelp keepers goes well beyond the surface.