Tag Archives: krill

Ocean Biologists Excited By Early Arrival Of Coldwater Copepods Off NW Coast

“Friendly faces” turned up earlier this year than last and for only the second time in the past four years off the Northwest coast, a “dramatic shift” that might be good news for salmon and other fish stocks.

FEDERAL BIOLOGISTS CALL IT “A WELCOME ARRIVAL,” THE RETURN OF COLDWATER COPEPODS TO THE NORTHWEST OCEAN. (NWFSC)

Federal biologists say offshore samples they’ve been collecting in recent months have been “full” of three different species of coldwater copepods, and they report “healthy” numbers of adult krill are also being seen.

“These are all good indications that the zooplankton community is transitioning back to a more ‘normal’ state,” writes Samantha Zeman on the Northwest Fisheries Science Center’s always interesting Newportal blog.

It’s been all out of whack since The Blob began to affect the northeast Pacific beginning in 2013, with the “hangover” from the humongous pool of too-warm saltwater continuing into last year.

“These coldwater copepods are lipid-rich and represent a productive food chain for higher trophic levels,” explains Zeman.

Their arrival also marks a “biological spring transition” that is key for coho and Chinook, with the earlier they’re seen translating to higher survival for silver salmon.

“This is especially exciting because in recent years (2015 and 2016) we never saw the copepod community transition from a warm winter community to a cold summer upwelling community, and in 2017 the transition occurred very late in the season,” Zeman writes.

An NWFSC chart showing transition dates since 1970 simply says “Never” for both 2015 and 2016.

In the former year, the annual June survey of juvenile salmon at sea was marked by emaciated coho.

A SIDE-BY-SIDE COMPARISON OF JUVENILE COHO MADE IN 2015 BY THE NORTHWEST FISHERIES SCIENCE CENTER SHOWS A HEALTHY ONE AT TOP AND A SAD-EYED ONE IN POOR CONDITION AT BOTTOM. (NWIFC)

Sampling also began turning up pyrosomes, a tubular organism that feeds on plankton and is generally found in more tropical waters, but the numbers of which exploded last year, fouling fishing gear from Oregon all the way to Alaska. A new study suggests they may be adapting to our cooler ocean and could become a permanent part of the biome.

PYROSOMES CLING TO A WESTPORT ANGLER’S DOWNRIGGER BALL DURING 2017’S SALMON SEASON. (SALTPATROL.COM)

NWFSC’s chart also shows that coldwater copepods have otherwise been present for as long as 263 days in 2007 and 252 in 2009 to as few as 29 in 1983 and 57 in 2005.

The spring transition has begun as early as March 4 in 2008 and around the first day of spring in 1970, ’71, 2007 and ’09, to as late as July 21 in 1983 and June 28 in 2017.

Meanwhile, we’re waiting to learn more about results from this June’s juvenile salmon sampling.

Last year’s turned up some of the lowest numbers of juvenile Chinook and coho seen in the past two decades, which federal biologists could translate into “lean times” this year and next for some rivers’ stocks, including the Columbia.

But with the earlier arrival of copepods, hopefully this year’s fish are faring better.

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.”