Reddish-brown patches in the water of Gastineau Channel as seen from the Douglas Bridge on Tuesday, July 31, 2018. (Michael Penn | Juneau Empire)

Reddish-brown patches in the water of Gastineau Channel as seen from the Douglas Bridge on Tuesday, July 31, 2018. (Michael Penn | Juneau Empire)

Possible algae increase dyeing Gastineau Channel waters red

No reason to believe it’s dangerous, scientists say

Eric Prestegard saw it for the first time Sunday.

A shade of rust-colored red crept its way through the waters of Gastineau Channel as Prestegard, the executive director of Douglas Island Pink and Chum (DIPAC) Inc. watched and worried. This is a vital time of year for the hatchery, which is midway through its egg taking process, Prestegard said.

Two days prior to that, the Alaska Department of Environmental Conservation had gotten a call that something unusual was floating around in the channel. Dave Pikul, an environmental program specialist for the Southeast Region’s Spill Response Unit, went down to the water and took a look.

“It was pretty widespread,” Pikul said. “Our observations down at the shoreline identified it was not oil, but it was some kind of biological mass.”

Exactly what that biological mass is, however, is still yet to be determined. Kate Kanouse, a habitat biologist for the Department of Fish & Game, said the overriding current theory is that it’s an algae bloom, or algal bloom. An algae bloom is a rapid increase in the amount of algae in the water, usually brought on as a result of rising water temperatures.

“That’s the most likely cause,” Kanouse said. “We’ve had a nice warm summer and it fits the criteria of what we would see of an algal bloom. I wouldn’t expect it to be anything else, and I don’t expect it to be dangerous.”

Algae blooms can be harmful, but not all of them are, according to the National Ocean Service. Vera Trainer, a research oceanographer with Northwest Fisheries Science Center, said blooms can cause a lack of oxygen in the water, which can kill small fish. More commonly in Alaska, she said, blooms affect shellfish.

“The most common in Alaska that are known of right now are the paralytic shellfish poisoning events that are resulting in accumulation of toxins in shellfish that can then be dangerous to humans,” Trainer said.

Trainer said algae blooms in Alaska are old news, as Aleuts have known about toxic shellfish for generations. Trainer said people should pay attention to health authorities’ websites and announcements about shellfish.

For many in Juneau, the reddish hue of the water is a new sight. Prestegard said he can’t remember a time when algae or phytoplankton were this widespread, even in the hot summer of 2004.

As he’s watched from his spot along the channel, Prestegard said that so far, everything seems to be fine.

“We’ve observed it the last three days,” Prestegard said. “At this point, it doesn’t seem to be affecting our fish in any way, shape or form.”

Prestegard said they’re a bit concerned about their aquariums, though. While the fish seem to be holding up well, DIPAC employees aren’t certain that smaller animals will be so immune. Prestegard said the algae bloom — or whatever it might end up being — has not made its way right up to the hatchery quite yet, but they’re watching closely.

Trainer said blooms will likely become more and more common in Alaska as ocean temperatures continue to rise. As ice melts, she said, sunlight will penetrate the water easier and promote more growth among plant life such as algae.

“Certainly with warming water,” Trainer said, “there’s going to be a larger suite of algal bloom problems that can occur in Alaska.”


• Contact reporter Alex McCarthy at 523-2271 or amccarthy@juneauempire.com. Follow him on Twitter at @akmccarthy.


More in News

Jasmine Chavez, a crew member aboard the Quantum of the Seas cruise ship, waves to her family during a cell phone conversation after disembarking from the ship at Marine Park on May 10. (Mark Sabbatini / Juneau Empire file photo)
Ships in port for the week of June 8

Here’s what to expect this week.

Bill Thomas, a former Republican state representative from Haines, announced Friday he is dropping out of the race for the District 3 House seat this fall. (U.S. Sustainability Alliance photo)
Bill Thomas drops out of District 3 House race, says there isn’t time for fishing and campaigning

Haines Republican cites rough start to commercial season; incumbent Andi Story now unopposed.

U.S. Rep. Mary Peltola, D-Alaska, speaks at the Alaska Democratic Party’s state convention on May 18 at Elizabeth Peratrovich Hall. (Mark Sabbatini / Juneau Empire file photo)
Peltola among few Democrats to vote for annual defense bill loaded with GOP ‘culture war’ amendments

Alaska congresswoman expresses confidence “poison pills” will be removed from final legislation.

A celebratory sign stands outside Goldbelt Inc.’s new building during the Alaska Native Regional Corporation’s 50th-anniversary celebration on Jan. 4. (Mark Sabbatini / Juneau Empire file photo)
Medical company sues Goldbelt for at least $30M in contract dispute involving COVID-19 vaccine needles

Company says it was stuck with massive stock of useless needles due to improper specs from Goldbelt.

(Michael Penn / Juneau Empire file photo)
Police calls for Wednesday, June 12, 2024

This report contains public information from law enforcement and public safety agencies.

A yearling black bear waits for its mother to return. Most likely she won’t. This time of year juvenile bears are separated, sometimes forcibly, by their mothers as families break up during mating season. (Photo courtesy K. McGuire)
Bearing witness: Young bears get the boot from mom

With mating season for adults underway, juveniles seek out easy food sources in neighborhoods.

A chart shows COVID-19 pathogen levels at the Mendenhall wastewater treatment plant during the past three months. (Data from the U.S. Centers for Disease Control and Prevention’s National Wastewater Surveillance System)
Juneau seeing another increase in COVID-19 cases, but a scarcity of self-test kits

SEARHC, Juneau Drug have limited kits; other locations expect more by Saturday.

Gov. Mike Dunleavy speaks to reporters during a news conference Feb. 7. (James Brooks/Alaska Beacon)
Gov. Dunleavy picks second ex-talk radio host for lucrative fish job after first rejected

Rick Green will serve at least through Legislature’s next confirmation votes in the spring of 2025.

A used gondola being installed at Eaglecrest Ski Area may not begin operating until 2027, according to Goldbelt Inc. President and CEO McHugh Pierre, whose company is providing $10 million for installation costs. (Eaglecrest Ski Area photo)
Eaglecrest Ski Area gondola may not open until 2027 due to CBJ delays, Goldbelt CEO says

Agreement with city allows Goldbelt to nix $10M deal if gondola doesn’t open by May 31, 2028.

Most Read