Millions of glowing sea creatures known as pyrosomes have begun to bloom off the Pacific Northwest of the United States and Canada, causing problems in the area as the strange-looking organisms fill up fishing nets and clog hooks.

Invasion Of The Strange-Looking Pyrosomes

Pyrosomes, also known as "sea pickles" and "fire bodies," are composed of multicellular creatures known as zooids. They can be recognized by their cucumber shape and transparent jelly-like exterior.

The creatures are often found in tropical waters, but they started to show up in spring. Over the past month or two, swarms of them have been seen. Some of them have even been spotted in Alaska.

Scientists, who have described the phenomenon as "the invasion of the pyrosomes," are baffled as to why populations of the tube-like creatures explode and overwhelm the water column.

The organisms may look harmless, but some fear their overwhelming presence could be a sign of more ominous issues. Their growing population is also feared to have unwanted consequences.

Fishermen worry that presence of these creatures may negatively impact a fragile food network. Salmon and halibut fishermen, for instance, have started to feel the effect of the growing population of pyrosomes. Some of them have not been able to access their normal catch. What they get instead of fish are pyrosomes on their hooks.

"When fishermen were trolling for chinook in midwater, they were dragging these lines with 50 hooks and they were coming up with these things on basically every hook," said Leon Shaul, from Alaska Department of Fish and Game. "It got to the point where they couldn't effectively fish."

Climate Change And Influx Of Pyrosomes

What's causing the influx of the pyrosomes? While the answer to this remains unclear, researchers have theories. NOAA research biologist Rick Brodeur and marine biologist Lisa-ann Gershwin suspect the phenomenon may be related to increasing water temperatures.

The population of the strange creatures may have something to do with a warm water blob that temporarily transformed the eastern Pacific in 2014 and 2015. When this happened, animals appeared in places where they did not belong. Warm-water sharks and tunas, for instance, were caught in the cold waters of Alaska. Tropical sea snakes also emerged in California.

A handful of pyrosomes washed ashore, but for some reasons, even after the temperatures started to cool and the rest of the sea appear to have reverted to normal, the creatures started to multiply and dominated relatively large portions of the sea by early spring.

Further studies are needed to know if there is a definite connection between the appearance of pyrosomes and climate change.

"We have a lot of questions and not many answers," said Brodeur. "We're trying to collect as much information as we can to try to understand what is happening, and why."

Researchers also said that it may be too soon to say if the creatures will become permanent residents of the Pacific Northwest.

"We'll have to wait to see how it goes, but certainly, it's not a good sign for the ecosystem to have these critters out there instead of the normal fish and crustacean prey most fish, birds and mammals off our coast are accustomed to," Brodeur said.