Biologists ponder effects of a warmer ocean as pink salmon fry leave early

 

And, they’re off! This season’s first batch of salmon fry will soon be entering the open ocean with lots of food and plenty of predators. Some will be back in a few years to spawn, others will be back as soon as next year after they swim a giant counterclockwise circle of the North Pacific.

But fisheries biologists wonder about one salmon run that just left Juneau’s Auke Creek earlier than ever before. And they’re curious about how a new, large mass of warm ocean water will affect those young salmon as they grow up.

“It’s good to separate them because the little fish don’t like being in with the big fish,” says John Joyce, a fisheries research biologist with the National Oceanic and Atmospheric Administration, who points out the various cages for separating outgoing fry and smolt at the Auke Creek weir.

NOAA fisheries biologist John Joyce explains how different species and sizes of  out-migrating fish are routed into different tanks for hand counting at Auke Creek weir. (Photo by Matt Miller/KTOO)
NOAA fisheries biologist John Joyce explains how different species and sizes of out-migrating fish are routed into different tanks for hand counting at Auke Creek weir. (Photo by Matt Miller/KTOO)

“There’s physical characteristics on the shape of their fins and the shape of their eyes, and their coloration,” Joyce says. “You have the ability to tell them apart. But it does take some time to get your eye educated because we do rely on that to separate out the species.”

On the last day of April 2015, he counted just one pink salmon passing out of the weir. The tiny, inch-long fry is a straggler. Most of his or her 14,175 siblings have been hanging out in Auke Bay before venturing into the open ocean.

Based on data collected over the last 35 years at the weir, Joyce says Auke Creek’s out migration of pink fry is one of the lowest on record and two weeks ahead of schedule. Joyce suspects that recent mild winters and climate change are behind the subtle, yet steady trend of earlier pink migrations.

But Joyce is not so sure about another relatively new phenomenon of a huge, evolving, moving mass of warm ocean water in the eastern North Pacific.

Washington state climatologist Nicholas Bond, who nicknamed it “The Blob”, says they’re not quite sure how it will affect Alaska salmon, but he believes it’ll be bad news for Lower 48 salmon since the warmer water attracts less nutritious prey species.

“We do know that in 2014, because of that warm water, that the base of the food web production of phytoplankton that supports the whole food web was reduced because that warm water served to isolate the near surface waters from the more-nutrient rich water below,” Bond says.

Over the last two winters, The Blob has moved and stretched out along the West Coast from the Gulf of Alaska down to Baja California. That’s right in the counterclockwise path of pink salmon coming home this year. How will they be affected? For the answer, Joyce refers to a prognosticating colleague at NOAA’s Ted Stevens Marine Research Institute whom he calls ‘Joestradamus’.

Research fisheries biologist Joe Orsi says they’re cautiously optimistic about a strong run of about 55 million fish this year. Those pinks will be the children of 2013’s big return. But they’ll be running through The Blob as they approach the Oregon shore and start heading north.

“The implications of climate change on fish species is important, for them all,” Orsi says.

“Salmon will be first ones reporting back to us if there’s a problem out there,” Orsi says. “We’ll know this year if the warm blob of 2014 caused something terrible to happen to the pink salmon because they’re just basically not going to return in high numbers this year.”

Pink salmon or humpies usually don’t get a lot of love. They’re physically smaller than the other four Pacific salmon species. But they’re still a major part of the Southeast Alaska commercial salmon industry, worth $124 million during 2013’s blockbuster season. They’re also ecologically important with the fry serving as food for their larger Chinook and Coho cousins. Bears, eagles, and marine mammals like whales will go for the adult humpies.

Orsi also wonders about those pink fry heading out from Auke Creek earlier this spring. He uses the term “mismatch” to describe how the out-of-sync fry may wander around and wait for their zooplankton breakfast to show up.

“If they can’t grow, they spend more time in the near shore, the littoral zone near the beach, when they’re small,” Orsi says. “They’re more vulnerable to predators, both avian and fish predators. They need to grow to a certain size before they actually start moving off shore and migrate out into open waters.”

And how will The Blob affect those out migrating, still developing pinks? Orsi says salmon will grow faster in slightly warmer water, but they’ll also need more food. And the warmer water could attract other unusual species and potential predators like blue shark and thresher shark, and Humboldt squid.

NOAA fisheries biologist Joe Orsi poses with Humboldt squid caught during a 2005 Gulf of Alaska survey that coincided with a warm water event. (Photo courtesy of Joe Orsi)
NOAA fisheries biologist Joe Orsi poses with Humboldt squid caught during a 2005 Gulf of Alaska survey that coincided with a warm water event. (Photo courtesy of Joe Orsi)

Excerpt of interview with NOAA’s John Joyce at the Auke Creek weir:

Joyce says they won’t be getting any quick and easy answers about the effects of The Blob. They’ll also have to consider other ecosystem factors.

“It’s all very interesting how these populations can optimize their productivity over time, be successful, and continue to deal with changing environmental conditions,” Joyce says.

“They have the ability to adapt and to change their behavior,” Joyce says. “At what point is it too much or too little?”

Biologists may find a few clues about the effects of warm ocean water when the first pink salmon from the 2013 brood year begin returning home to Auke Creek in August.

Support critical access for all. Become a member today.