Trolling fishermen along the Northern California coast have been getting their tackle in a tangle over jellyfish.
It”s not unusual to see more of the ghostly, sometimes glowing, floating creatures at this time of year, when upwelling currents near the shore typically weaken, allowing ”oceanic water”, and the sea life it carries, closer to land.
But this year”s jelly crop seems especially thick, according to charter boat Capt. Randy Thornton, and sea-watchers in places all over the world report seeing more jellyfish close to shores, with guesses but no conclusions about the cause.
According to Pete Kalvass, State Department of Fish and Wildlife biologist at Noyo Harbor, two types of jellyfish are common in local waters: moon jellyfish (Aurelia aurita) and brown jellyfish (Chrysaora melanaster), also known as a sea nettle.
Large numbers of the creatures have appeared in waters off the Mendocino Coast over the past few weeks, to the point where fishermen report it has impacted their ability to troll for salmon because lines get snagged.
Thornton said he has noticed the white and brown varieties, and an orange one even bigger than the brown, which carries the local nickname “goober.”
The Japanese sea nettle is orange. That cousin of the brown sea nettle has been reported interfering with fishing in the Sea of Japan:
“The fishermen”s nets are getting weighted down, or even broken, by hundreds of jellyfish. The jellies crush, slime, and poison valuable fish in the nets, such as the tuna and salmon that the fishermen rely on to make a living,” says an article called “Giant Jellyfish Invasion” in National Geographic Kids online magazine.
In fact, jellyfish are in the news quite a bit lately. Last week, billions of By-the-wind sailors (not really jellyfish but close) arrived on Washington State beaches. This week, a jellyfish swarm stung more than 400 people at a beach in Florida. The August issue of National Geographic magazine has an article called “Why Are Jellyfish Swarming This Summer?” which details global reports of a rise in jelly swarms. Irish publications are especially watchful. Millions of Mauve stinger jellyfish have killed large parts of Irish farmed salmon stocks more than once over the past several years. Jellyfish have invaded fish farms in Scotland and Florida as well.
“One scientist has said that the surge in jellyfish numbers has been ”sending us a message in a bottle.” Over-fished seas and global warming have cleared the way for them to prosper, and their population explosion is part of an international phenomenon,” said a recent article in the Irish Independent.
Some scientists think jellyfish populations are taking off because of warming oceans and possibly fertilizer pollution that causes plankton blooms, which can cause jellyfish populations to explode as well.
It could be a factor driving such things as the reappearance of giant jellyfish in the Adriatic Sea for the first time in 60 years, and the appearance of very poisonous Lion”s Mane jellyfish off the Irish coast. Both the Adriatic and the west coast of Britain are seeing higher than average ocean temperatures, as is the Northern California coast. That is not the same thing as saying the ocean in general is warming in those places, as ocean temperature often depends on current.
On the other hand, the end of summer has always been jellyfish season. Randy Davis, captain of the Salty Lady in San Francisco Bay, said jellyfish haven”t been particularly bad in his area, and are an occasional problem around this time of year.
“It”s nothing new,” he said.
