On a sunny spring day on the California coast, a crowd of people snap photos of sea otters floating on the waves. Lately, sea otter sightings like this one have become more common in California. The state’s sea otter population is higher than it has been in decades. Scientists say the increase is something to celebrate. Sea otters aren’t just cute. They also help keep their ocean habitats healthy—and even play a role in protecting the planet from pollution (harmful materials that damage air, soil, and water).
BACK FROM THE BRINK
Hundreds of thousands of sea otters once lived in the northern Pacific Ocean. But in the 1700s, people began hunting them for their thick fur. Hunting sea otters was banned in 1911, but by then fewer than 2,000 were left.
Starting in the 1960s, scientists began moving some otters to places where they had completely disappeared. Over the years, sea otter populations have grown. Today there are about 125,000 otters, mainly near Alaska.
Scientists recently counted more than 3,200 sea otters near California. It’s the highest number they have found in that area in decades.
Sea otters are a keystone species. That means they play a major role in their ecosystems (communities of animals and plants interacting with their environments). “There aren’t a lot of them,” says scientist James Estes. “But they have a very big impact.”
Estes explains that otters love to chow down on spiky creatures called sea urchins. That’s important because too many sea urchins can cause big problems in the ocean. Sea urchins eat kelp, which is a type of giant seaweed that grows on the ocean floor.
When sea otters aren’t around, urchins often gobble up all the kelp in an area. That leaves animals like seals, fish, and crabs without a source of food or shelter. Kelp forests are also important in another way. They help absorb (take in) a gas called carbon dioxide. When people burn fuels to power cars and factories, large amounts of this gas are released into the air. It even gets into ocean water. There, it can cause problems for marine animals. For example, it can make it harder for some sea creatures to form shells.
By keeping the populations of sea urchins under control, sea otters help kelp forests grow—and other ocean animals survive.