The blobs that ate our oceans -- Are jellyfish the cockroaches of a climate-warmed seas?

Michael Casey's lede from Kokonogi, Japan makes it hard to stop reading, eh?

A blood-orange blob the size of a small refrigerator emerged from the dark waters, its venomous tentacles trapped in a fishing net. Within minutes, hundreds more were being hauled up, a pulsating mass crowding out the catch of mackerel and sea bass.

Dinnertime! Yum, jellyfish again!

That's what it could come to, a leading fisheries expert believes. But first, a few more details from Casey's story for the Associated Press that was published this week:

• These explosions in jellyfish explosion along the Japanese coast used to occur maybe every 40 years or so. Now they're becoming pretty much an annual affair.
• They're occurring along thousands of kilometers of the Japanese seaside, imperiling the livelihoods of Japanese fishermen.
• These jellyfish blooms are thought to be increasing along with climate change, (although I have to note: that could be correlation rather than causation. Read on.)
• Another factor that could be at work is overfishing of the jellyfish's predators.

According to the National Science Foundation, jellyfish are about the only living creatures in some 400 ocean "dead zones" around the world. This suggests that they survive pollution better than other creatures. The NSF noted that Europe's horribly polluted Black Sea "was transformed into a veritable jellytorium" in the '90s.

A big NSF report also detailed jellitorium-like conditions in Australia, the Gulf of Mexico and the U.S. East coast.

It appears that warm temperatures may be allowing some jellyfish to expand their range.

But it's not a linear correlation. In the Bering Sea, for example, jellyfish populations exploded in the 1990s -- but moderated after 2000, when the water warmed demonstrably. (Of course, one possibility is that the population decrease was related not to water temps, but rather to overfeeding by the massive numbers of jellyfish, which could have knocked back the plankton they feed on, leading to lower numbers of jellyfish. If so, that gives me pause, because it suggests these perturbations are beginning to muck with the carrying capacity of the oceans that feed us.)

And right in Washington's San Juan Islands, something similar happened, Lisa Stiffler and I discovered in researching a big project on the decline of Puget Sound.

Casey's image of the sea bass and mackerel being crowded out of the Japanese fishing net by grotesque seagoing blobs perfectly encapsulates what could happen across vast swaths of the ocean.

Casey's piece is not the first word of an impending Great Jellyfish Explosion. My ears perked up when I was covering a conference a few years ago where a fish scientist started talking about the declining biodiversity of the oceans. That story started:

Jellyfish?

That's the picture of the not-too-distant future painted yesterday for 1,500 fisheries scientists from around the globe by one of the world's leading fisheries researchers, Daniel Pauly of the University of British Columbia.

Bon appetit!

-- Robert McClure