Warm-water fish increasingly spotted in Alaska waters

Scientists and fishermen have reported more unusual species in Alaska waters, likely because of warming sea surface temperatures. Meanwhile, an Alaska research organization has created an online clearinghouse of all the news and research related to the anomaly called The Blob.

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An ocean sunfish is captured in research trawl in July 2015. (Image courtesy of National Oceanic and Atmospheric Administration)
An ocean sunfish is captured in research trawl in July 2015. (Image courtesy of National Oceanic and Atmospheric Administration)

Many of the unusual sightings this summer have been of mola mola, or ocean sunfish. They’re the heaviest known bony fish in the world, and they’re normally found in temperate and tropical climates where ocean temperatures are at least 50 degrees Fahrenheit — not the North Pacific.

“It’s really interesting when you see a fish from a thousand feet that looks like a bedsheet floating in the ocean,” says Scott Pagau of the Oil Spill Recovery Institute in Cordova. Pagau says he and a colleague spotted as many as four large sunfish during their August aerial surveys off of Hinchenbrook Island.

“I used to do work in the tropics and had seen the fish on the surface in the past,” Pagau says.

“You don’t expect to see it so you kind of go. ‘Did I really see a mola mola down there?’”

Pagau says three of the four sunfish were swimming upright, but the largest was about 7 to 8 feet long and about 4 to 5 feet tall.

“And it was laying on its side, kind of sunning itself,” Pagau says. “It’s got these two little fins in back that kind of flop around a little bit. That’s what really kind of grabs your attention. Not only is it something big in the ocean, but it’s got an odd little movement to it.”

Joe Orsi, research fisheries biologist at NOAA’s Ted Stevens Marine Research Institute, says they caught a 900-pound sunfish back in June while pulling a surface research trawl for juvenile salmon. They caught a 400-pound sunfish during another trawl in late July. An underwater camera recorded video of the flat fish as big as a door drifting into the trawl with its fins flapping around while trying stay upright.

NOAA research fisheries biologist Joe Orsi narrates this video of a large ocean sunfish captured in a surface trawl off of Icy Point in July 2015. Video courtesy NOAA. 

Orsi says it’s pretty striking to catch ocean sunfish two months in a row.

We’re only doing four trawls offshore there,” Orsi says. “So, it’s just a very strange coincidence for them to occur that soon back to back.”

Orsi says they released the sunfish after taking its measurements.

Commercial fishermen have also reported catching the large subtropical fish while seining for pink salmon in Southeast Alaska. Pictures of the unusual catches were posted on Facebook in early August.

“We’re seeing some odd occurrences this year out in the open ocean because of the warmer temperatures,” Orsi says.

Orsi says Pacific sea surface temperatures are at least 1 degree Celsius above the 19 year average, and the ocean sunfish is not the only species reported found in warmer Alaska waters. Their trawl camera in late July captured video of market squid drifting through the trawl and Pacific pomfret darting in and out. Those are more temperate marine species.

They’ve also received reports of market squid spawning off of Little Port Walter on Baranof Island, albacore sighted off Noyes Island, and Pacific bonita caught in the Ketchikan area.

In addition to the sunfish, Orsi remembers catching other unusual species over the previous two summers.

“The thresher shark that was caught in the survey was the furthest north ever recorded,” Orsi says.

Orsi and his colleagues just returned last week from their latest trawl survey. Nothing unusual was found this time around.

He says the big question is how are Alaska’s salmon affected by the warmer temperatures and the appearance of unusual species?

Stories about the sunfish catches and other unusual ocean phenomena have been compiled in a blog called the Alaska Blob Tracker created by the Alaska Ocean Observing System. The Blob is the nickname assigned to a large mass of warm surface temperatures in the North Pacific that has stretched down to the California coast.

Carol Janzen, AOOS’s director of operations and development, says The Blob has been showing up in the news periodically.

“I think people are noticing the weather and the warmer-than-usual conditions up here in Alaska, dry conditions,” Janzen says. “And they’re seeing it on the national news, too, because this particular feature has affected pretty much the west coast of the United States.”

The Blob is different than El Niño, which just formed in the tropics and is gaining strength. The Blob has increased temperatures an average of 2 degrees Celsius since it was discovered in spring of last year.

“It’s been a fairly persistent feature which is what makes it so interesting and unusual,” Janzen says.

The Blob may be a factor behind the ongoing drought conditions on the West Coast and algae blooms that have crippled shellfish fisheries offshore.

It’s still unclear how The Blob and El Niño will interact and how they will affect fisheries, marine mammals and weather.