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Masses of dead jellyfish in Alaska waters not unusual, says NOAA scientist

  • Author:
  • Updated: September 28, 2016
  • Published September 30, 2014

A jellyfish graveyard that settled on the beach of Clam Gulch last week proved a peculiar sight for some locals and prompted curious phone calls to the Alaska Department of Fish and Game.

But there's nothing unusual about the high number of lifeless jellyfish pushed ashore there, a biologist says. National Oceanic and Atmospheric Administration research fisheries biologist Kristen Cieciel says the jellyfish live only about a year and die off in the fall.

Chrysaora melanaster, more commonly known as the northern sea nettle, can grow to 23 inches across and weigh up to 8 pounds. "These sea nettles are the kinds of jellyfish people think of when they picture jellyfish," said Cieciel.

She said a typical jellyfish life cycle begins with the release of sperm and eggs from male and female jellyfish. A fertilized egg will then form into a larva, which floats near the water's surface. The larva eventually settles and becomes a polyp, which looks similar to a sea anemone.

"It will eventually kind of look like a pine cone, but really it is like nine to 15 jellyfish," Cieciel said. "They will release like little Frisbees in the water."

She said there is little time in the jellyfish's brief lives to do too much beyond growing, gaining energy and reproducing before they die. Cieciel noted that in mid-September she spotted numerous sea nettles floating dead in the northern region of the Bering Sea during a research voyage from Nome to Dutch Harbor.

Where a jellyfish's body ends up depends on weather and current, as well as how close to shore they were when they died. Cieciel added jellyfish often end up on Alaska beaches.

Sea nettles, which live as far north as the Chukchi Sea and as far south as California, are just one of several jellyfish species living in Alaska waters, all of which live similar, short life cycles.

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