In a glacial fjord in Southeast Alaska, a group of sea otters has gathered at a big kelp. Some have draped kelp blades across their bodies so they won't drift away as they doze in the spring sunshine. Otters are good for kelp, in a roundabout way, and this kelp bed is far larger than it was 20 years ago. Here's why:
Sea otters are relatively new here, although they were a part of this ecosystem for thousands of years after the glaciers that carved these fjords retreated. They were harvested in small numbers for their fur by Native Alaskans, but in the 1800s, Russian and British fur traders wiped them out. Sea otters eats eat sea urchins, and in the absence of sea otters, sea urchins thrived. And sea urchins eat kelp.
In the early 1970s, a few hundred sea otters from a surviving Aleutian Island population were re-introduced to Southeast Alaska. With abundant prey the otters thrived and they've grown to number in the tens of thousands. Feeding heavily on sea urchins -- kelp beds have noticeably expanded.
Fishermen harvest close to 80,000 blades of macrocystis kelp each spring in Southeast Alaska for the herring roe on kelp fishery and they've noted the increase.
"The kelp beds are just huge now because of the sea otters, there's no shortage of kelp," one fisherman told me.