Jellies belly up — Life’s no beach for jellyfish washing ashore in large die-off

Photo by Joseph Robertia, Redoubt Reporter. Jellyfish have been washing up on Kenai Peninsula beaches for the past few weeks, with the highest concentrations between clam Gulch and Kasilof. The die-off of jellyfish is part of its annual life cycle, but it usually occurs later in the year and doesn’t often leave such noticeable evidence.

Photo by Joseph Robertia, Redoubt Reporter. Jellyfish have been washing up on Kenai Peninsula beaches for the past few weeks, with the highest concentrations between clam Gulch and Kasilof. The die-off of jellyfish is part of its annual life cycle, but it usually occurs later in the year and doesn’t often leave such noticeable evidence.

By Joseph Robertia
Redoubt Reporter

The low-angle sun setting behind volcanoes across the glimmering water and painting the sky a vivid orange red, the last of the seasonal birds calling out overhead, the cessation of seasonal crowds and the lapping of waves breaking on the smooth stones and sand of the shore — going for an evening stroll on the beaches of Cook Inlet can be a serene endeavor in the fall.
But this year, beach walkers are finding the aesthetics of this autumnal experience impacted by a strange sight — thousands of slimy, brown, gelatinous jellyfish strewn along the surf.
“I usually get a couple of calls a year from people back in bays, but this year there’s been a lot of calls coming in, many from the Kenai Peninsula. There seems to be more washing up earlier and at once,” said Kristin Cieciel, a research fisheries biologist with the National Oceanographic and Atmospheric Administration in Juneau.
The species of jellyfish she is referring to is Chrysaora melanaster, commonly called the Northern sea nettle or brown jellyfish. Its genus ranges along the entire west coast of Canada and the Lower 48, but this particular species makes its home from the Gulf of Alaska north to the Chukchi Sea.
For the past 10 years, NOAA has conducted numerous fisheries and oceanographic surveys around the state, of which a jellyfish component has been an integral part of a much broader fall survey for pollock, cod and salmon. The jellyfish are caught while surface-trolling in such large quantities that they’re counted not by numbers, but by weight.
“This year we had catches that were enormous. The final numbers are still coming in, but anecdotally I can say the numbers were in the tons,” Cieciel said.
This isn’t particularly out of the ordinary for jellyfish, but two things did strike her as odd. The surface temperatures were higher than average — as much as 5 degrees above average by some estimates — and many of the jellyfish she was seeing were already beginning to die.
“When they’re dead, they just float there and often with damaged tentacles or no tentacles at all, but when alive they’ll be pulsing and moving up and down the water column, and their tentacles, which are around 3 to 9 feet long and spindly, are easily noticeable,” she said.
“The thought is that this species only lives one year. In earlier winter the gametes — eggs and sperm — are released, and by fall that’s it for them. But, the annual die-off is usually later. It’s usually October that we start seeing them die off. This year I was seeing them dying in the southeast Bering Sea survey at the end of August and in September,” Cieciel said.


It’s too soon to say if the warm surface temperatures are directly correlated to the early die-offs, she said, but there have been sightings of numerous warmer-water species of fish reported in Alaska this season, including a mola sunfish caught in Prince William Sound, a skipjack tuna caught in a salmon net off of the Copper River and a thresher shark photographed near Yakutat earlier this summer.
The jellyfish dying earlier is only part of the conundrum. There also is the mystery of why so many are showing up on Cook Inlet beaches.
“We really don’t have an answer for that yet. It could be related to storms or current. We just don’t know at this time,” Cieciel said.
The ones washing up from Homer to Ninilchik are typically clear or golden with a brownish to reddish tint, sometimes with a darker sun pattern of stripes. And unless washed back to sea, they’re likely to stay onshore. Unlike salmon, halibut and flounder carcasses, which are feasted on by eagles, gulls and occasionally bears and other carnivores, the jellyfish just linger on the shoreline until the sun, wind and elements claim them.
“Seabirds will peck at them, but nothing really eats them. They’re basically just water, though, so there’s not a lot of odor associated to their decomposition,” Cieciel said.
Still, she said that people shouldn’t move them.
“It’s a stinging species, so even with the tentacles damaged or broken off, they still shouldn’t be handled,” she said.

Leave a comment

Filed under Cook Inlet, ecology

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s