"It was a big mystery," Lubchenco said. "We didn't know what was killing them."
"I'd tell my crewmen, be careful with these cute little things," said Dennis Krulich, a longtime fishermen in Newport. "Peel them off the rope, and we'll put them back."
Only later did he realize that these babies were coming up from oxygen-depleted waters that hover near the seafloor, climbing to save their lives. "In 30 years of crabbing, I'd never seen anything like it before, Krulich said. "It's spooky, this dead-zone thing."
The size of the zone has fluctuated over the years. In 2006, it was the largest ever measured, covering an expanse slightly larger than Rhode Island.
Last year, it was smaller but detected over a longer stretch of coastline.
To make sure the phenomenon was actually new, Oregon State marine ecologist Francis Chan reconstructed data from water sampling at 3,100 stations dating to 1950.
He found that low-oxygen areas have long existed in deeper waters, but there was virtually no evidence until recently of hypoxic waters in prime fishing waters, which extend down to 165 feet.
"It's pretty clear this is unprecedented," Chan said. "It's never been detected since we began to measure oxygen levels."
So far, the seasonal dead zones, which begin as early as June and wrap up in September, have not hurt the crab fishery, which mostly operates in the winter. Many crabs and fish manage to flee the low-oxygen area. And fishermen have learned to set their traps in the wasteland of the previous year's dead zones, to catch crabs that return to feed on the detritus of all the suffocated animals.
Scientists say seafood caught in low-oxygen zones is not harmful to eat.