Tag Archives: PYROSOMES

Survey Finds Good Krill Numbers Again Off Oregon, But Even More Pyrosomes

An annual spring survey off the Northwest Coast came up with some good and bad news for key stocks.

Krill — hugely important near the base of the ocean food web — and young Dungeness crab numbers were as high as they’ve been in some time, but there are even more pyrosomes off Oregon’s Central Coast and to the south than last year.

RESEARCHERS CALLED THE RETURN OF KRILL TO THEIR SAMPLING NETS “A WELCOME SIGHT SINCE THESE IMPORTANT FORAGE HAVE LARGELY BEEN ABSENT OVER THE PAST COUPLE YEARS SINCE THE ANOMALOUS WARMING” FROM THE BLOB. (NWFSC)

Jennifer Fisher, fresh off a 10-day survey between San Francisco Bay and Newport, reported the findings on the Northwest Fisheries Science Center blog.

“These are the most Dungeness larvae and juveniles we’ve collected in a long time, and we have not seen krill numbers like this since before 2015,” Fisher followed up via email.

That year, 2015, was the height of The Blob — the huge pool of warmer than usual water in the Northeast Pacific that messed things up at sea and on land — and it was also a year after pyrosomes first began to be found in our coastal waters.

By last year, the tropical gelatinous, sea-pickle thingies that are actually colonies of organisms were clogging fishing gear off our coast and even turned up as far north as the rim of the Gulf of Alaska, also a first.

While rockfish were observed feeding on pyrosomes, it’s not clear how their numbers will affect the food web. Another NOAA blog from last October states, “At this point, there are more questions than answers.”

But the May survey answered the question whether they’re still out there.

“The pyrosome catches appear slightly larger and the colonies are larger compared to last year,” reports Fisher.

They can be found starting about 10 miles off the coast, living on the bottom during the day and rising to the surface at night.

PYROSOMES FILL A COOLER ABOARD THE NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION’S VESSEL, THE BELL M. SHIMADA. (NWFSC)

The Science Center will soon conduct another closely watched spring survey, collecting information on young Chinook and coho off Oregon.

Last year’s produced very low catches while one a couple years ago found very small fish. But the resurgence of krill is a hopeful sign that the food web could be rebuilding coming out of the hangover from the Blob.

Fisher also reported on Science Center’s blog that copepods are in a state of flux between winter warm-water communities and summer, cold-water ones that come with the upwelling.

So what does it all mean?

“The krill is a good sign, but the pyrosomes are not, since they are indicative of warm water,” she says. “And the transitional copepod community is also not a great sign for salmon. But it’s still early in the summer upwelling season, so things can certainly change.”

‘Unprecedented’ Pyrosome Explosion Off Northwest Coast; Not Seen Before 2014

THE FOLLOWING IS A NEWS STORY FROM THE NATIONAL MARINE FISHERIES SERVICE’S NORTHWEST FISHERIES SCIENCE CENTER

By Michael Milstein

Call it the invasion of the pyrosomes.

Researchers from NOAA Fisheries’ Northwest Fisheries Science Center are collaborating with colleagues from Oregon State University and the University of Oregon to unravel the mystery of why the strange jelly-like organisms have exploded in number off the Northwest Coast in recent months.

PYROSOMES ARE “BASICALLY LIKE WADS OF GOO” THAT DON’T DO MUCH FOR THE FOOD CHAIN BUT EAT PLANKTON THAT OTHERWISE MIGHT HAVE FED ORGANISMS THAT YOUNG SALMON WOULD HAVE EATEN. (HILARIE SORENSEN/NOAA FISHERIES)

Generally found in more tropical waters around the globe, the tubular pyrosomes were rarely if ever seen off the Northwest until about two years ago. They have since multiplied and this spring appear to be everywhere off the Oregon Coast to the point they are clogging fishing gear by the thousands.

A five-minute midwater tow of a research net off the Columbia River in late May brought up approximately 60,000 pyrosomes. Scientists spent hours sorting through the massive catch to find the rare fish they were targeting.

A LONGTIME FEDERAL RESEARCHER BASED IN NEWPORT SAYS THAT HE’D NEVER SEEN PYROSOMES HERE BEFORE 2014. A NUMBER OF THEM COVER FISHING GEAR. (HILARIE SORENSEN/NOAA FISHERIES)

“We have a lot of questions and not many answers,” said Ric Brodeur of the Northwest Fisheries Science Center’s research station in Newport, Oregon. Brodeur has worked off the Oregon Coast since the 1980s and had never seen a pyrosome before 2014. “We’re trying to collect as much information as we can to try to understand what is happening, and why.”

Underwater video captured by the NOAA research ship Bell M. Shimada in May show legions of pyrosomes in extremely high densities from approximately 40 to 200 miles off of the Oregon Coast. They ranged in size from 4-6 cm (about an inch) to a whopping 78 centimeters, or more than two feet long. Researchers found larger and more abundant pyrosomes farther offshore.

PYROSOMES RANGE FROM A FEW INCHES TO MORE THAN 2 FEET LONG. (HILARIE SORENSEN/NOAA FISHERIES)

Pyrosomes are as mysterious as they are strange. Each pyrosome is made up of individual zooids – small, multicellular organisms – linked together in a tunic to form a tube-like colony that is closed on one end. They are filter feeders and use cilia to draw plankton into their mucous filter.

Some bony fish, dolphins and whales are known to eat pyrosomes, but scientists know little about their role in the offshore ecosystem or how they may affect the food web in areas where they are now appearing in such high densities.

“At first we didn’t know what to make of these odd creatures coming up in our nets but as we headed north and further off shore, we started to get more and more,” said Hilarie Sorensen, a University of Oregon graduate student who was aboard the Shimada on its May research trip off Oregon. “We began counting and measuring them to try to get a better understanding of their size and distribution related to the local environmental conditions.”

PYROSOMES DRIFT AT SEA. (HILARIE SORENSEN/NOAA FISHERIES)

Pyrosome numbers in the Northern California Current – which encompasses Northern California, Oregon and Washington – increased in 2015 and again in 2016. As far as scientists know, however, their abundance this year is unprecedented. Salmon and shrimp fisheries reported large catches of pyrosomes off Oregon early in the season and the odd organisms are turning up in large numbers as far north as Southeast Alaska.

The feeding behavior of pyrosomes, the environmental variables that may affect their numbers and their impacts on the food web are largely unknown. Researchers are interested in unraveling those mysteries by exploring pyrosome population dynamics and determining what could be driving such high abundances in the Northern California Current.