We otter get some help
KIN THE elp forests are a crucial California marine ecosystem. From kelp’s floating canopies to its “holdfast” roots, the giant seaweed—algae, actually—supports greater biodiversity and sequesters more carbon than a redwood grove.
Unfortunately, since 2013 the state’s kelp beds have been in an unprecedented state of collapse. From San Diego to Monterey the losses are patchy, and north of the Golden Gate more than 95 percent of the kelp is now gone. Warming oceans combined with past hunting and fishing practices upset the balance between predators and prey in the kelp forest, with devastating effects.
One possible remedy has a satisfying twist— return the sea otter, the keystone kelp forest predator, to its historical range along the North Coast.
Perhaps 300,000 sea otters once thrived along the north Pacific Rim from Japan to Baja until humans hunted them almost to extinction in the 19th century. They’ve rebounded since they were fully protected in the U.S. 50 years ago.
California’s kelp catastrophe has two immediate causes. In 2013, a marine heat wave that scientists dubbed “the blob” caused ocean temperatures to spike along the West Coast, weakening the kelp, which thrives in cold, nutrient-rich currents. Then a virus—probably supercharged by the warmer waters, according to a 2019 study—allowed purple urchins, voracious kelp eaters, to proliferate.
The virus, known as the sea star wasting syndrome, is on a par with horror movie scourges. It melts the limbs and bodies of what we used to call starfish, including the many-armed sunflower sea star, a purple urchin predator. On the North Coast, with sea otters long gone, sunflower sea stars have been the major purple urchin predator. Since the sea star die-off, the quarter-sized purple urchins have run amok.
Sea otters are nearly as insatiable as purple urchins. They lack the blubber common to other marine mammals and depend for warmth on their luxuriant fur (the prize that led to their slaughter in the 1800s). They run hot; their metabolism requires that they eat up to a quarter of their body weight each day in abalone, crab, octopus, and urchins.
North Coast fishermen may not welcome back otters. On the other hand, a lot of science— and in-the-water evidence at the Channel Islands and other MPAs (marine protected areas)—indicates that the more intact the near-shore ecosystem, with a healthy mix of predators and prey, the better the fishing will be in adjacent waters.
Conservationist Aldo Leopold once wrote, “To keep every cog and wheel is the first precaution of the intelligent tinkerer.”
On the North Coast, the way back to a healthy ocean will take planning, funding and cooperation and some intelligent tinkering. Reestablishing sea otters throughout their traditional range could be a start.