Millions of krill have been washing up on beaches in southern Oregon and northern California for the past few weeks, according to a report from Associated Press.
The reason why these tiny shimp-like creatures are washing ashore is unclear. National Oceanic and Atmospheric Administration oceanographer Bill Peterson says they may have been blown into the surf by strong winds while mating near the surface, and then been dashed on the beach, AP reports.
The species is Thysanoessa spinifera, and it helps form the basis of the marine food chain. Clouds of krill stretching for miles on beaches from Bodega Bay, California, to Newport, Oregon, are flooding beaches. Some of the krill are still alive when they wash ashore, according to AP.
"There has definitely been something going on," Peterson said from Newport. "People have sent us specimens. In both cases, the females had just been fertilized. That suggests they were involved, maybe, in a mating swarm. But we've had a lot of onshore wind the last two weeks. If they were on the surface for some reason and the wind blows them toward the beach and they are trapped in the surf, that is the end of them."
On the other hand, they may have fallen victim to low levels of oxygen in the water, said Joe Tyburczy, a scientist with California Sea Grant Extension in Eureka, California. A recent ocean survey showed lower than normal oxygen levels in some locations. If the krill went to the surface to get oxygen, they could have been blown on shore, he told AP. For some reason, people did not see gulls and other sea birds eating them, Tyburczy added.
Peterson said low oxygen conditions, known as hypoxia, are a less likely explanation because they normally occur later in the summer. The mass strandings are unusual, but not unheard of, Peterson reported to AP.
Krill represent a significant source of food for salmon, rockfish, lingcod and even whales along the Pacific Coast, but there is no way to tell yet whether this event will impact these or others marine species.