Early lives of Alaska sockeye salmon accelerating with climate change

Early lives of Alaska sockeye salmon accelerating with climate change
Adult sockeye salmon returning to spawn in the lakes of Bristol Bay, Alaska. Credit: Jason Ching/University of Washington

An ample buffet of freshwater food, brought on by climate change, is altering the life history of one of the world's most important salmon species.

Sockeye in Alaska's Bristol Bay region are skipping an entire year in freshwater because change has produced more favorable conditions in lakes and streams, which allow the young to grow and put on weight much faster. Previously, these fish would spend up to two years in their birth lakes before heading to the ocean, where they feed and reach maturity two to three years later. Now they are more likely to head out to sea after only one year.

These findings were published May 27 in Nature Ecology & Evolution by University of Washington researchers.

"Climate change is literally speeding up the early part of their lifecycle across the whole region," said senior author Daniel Schindler, a UW professor in the School of Aquatic and Fishery Sciences. "We know climate warming is making rivers more productive for the food juvenile salmon eat, meaning their is speeding up. That puts the salmon on a growth trajectory that moves them to the ocean faster."

But this "jumpstart" in freshwater doesn't necessarily benefit salmon in the long run. The same fish are now spending an extra year in the ocean, taking longer to grow and mature. This extra year at sea is likely caused by climate stressors, as well as other fish: In the ocean, wild compete for food with close to 6 billion hatchery-raised salmon released each year throughout the North Pacific Ocean. That number has grown steadily since the 1970s, when only half a billion hatchery salmon were released.

Early lives of Alaska sockeye salmon accelerating with climate change
Two-year-old juvenile sockeye salmon, like this one, are becoming less common in freshwater as warmer lakes have accelerated juvenile sockeye growth, leading them to enter the ocean after only one year. Credit: Jonny Armstrong

"Hatchery fish have really changed the competitive environment for juvenile salmon in the ocean," said lead author Timothy Cline, a postdoctoral researcher at the University of Michigan who completed this work as a doctoral student at the UW. "In Bristol Bay, the habitat is totally intact and fisheries management is excellent, but these fish are living in lakes warming with climate change, then competing with other salmon for food in the ocean."

The researchers drew on nearly 60 years of Bristol Bay sockeye data to tease out these changes over time, including information gathered by scientists and students in the UW's Alaska Salmon Program. Close to half of the world's wild sockeye is caught from this region, and more than 40 million fish usually return each year to Bristol Bay's nine river systems to spawn.

Higher temperatures in the region have caused lakes and rivers to warm up earlier each spring, fueling the growth of tiny plankton that young sockeye eat. This extra food essentially fattens up the fish a year earlier, triggering their migration to the ocean.

Early lives of Alaska sockeye salmon accelerating with climate change
Wild Bristol Bay sockeye salmon are competing for food in the ocean with hatchery-released pink salmon (pictured above) and chum salmon. Credit: Jason Ching/University of Washington

This trend could negatively impact the resiliency of the Bristol Bay sockeye population, the authors said. Before, not every fish in a particular "age class" would migrate to the ocean in the same year, and any given year would see fish of different ages moving out to sea. This diversity of ages has helped the species navigate risks and survive.

But now, most sockeye are migrating at the same time, as 1-year-olds. This could devastate an entire age class if the ocean conditions happen to be poor one year. Additionally, scientists don't know how many salmon the North Pacific can actually support.

"With , is there a limit to how productive the ocean will become? We just don't know where there's a tipping point, especially as we fill the with hatchery competitors," Schindler said. "We need to be really cognizant about overstressing the marine resources that support wild salmon."

Early lives of Alaska sockeye salmon accelerating with climate change
The lakes and streams that support wild salmon in Alaska’s Bristol Bay region are warming rapidly. Credit: Jason Ching/University of Washington

Co-author on the study is Jan Ohlberger, a research scientist at the UW School of Aquatic and Fishery Sciences.

The study was funded by the National Science Foundation and the Gordon and Betty Moore Foundation.


Explore further

Hot spots in rivers that nurture salmon 'flicker on and off' in Bristol Bay region

More information: Timothy J. Cline et al, Effects of warming climate and competition in the ocean for life-histories of Pacific salmon, Nature Ecology & Evolution (2019). DOI: 10.1038/s41559-019-0901-7
Journal information: Nature Ecology & Evolution

Citation: Early lives of Alaska sockeye salmon accelerating with climate change (2019, June 4) retrieved 15 October 2019 from https://phys.org/news/2019-06-early-alaska-sockeye-salmon-climate.html
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Jun 04, 2019
what did the poor benighted salmon do during the Holocene Climate Optimum, eh?

Jun 04, 2019
@Shootist.
what did the poor benighted salmon do during the Holocene Climate Optimum, eh?
No problem, mate. They were able to fatten up earlier in the river/lake where they hatched because of more food; and migrated earlier than otherwise. That is what the above study points out. The only drawback is the younger they are when they migrate to the ocean, the longer they take to mature there before returning as adults ready to spawn in the river/lake where they originally hatched. But as long as the ocean had plenty of zooplankton, it didn't matter when the fish leave their spawning grounds, or when they return. It's just the migration to/fro timing that changes, not the survival of the species per se. Although now that we depend on such fisheries for food, the timing may be problematic if the fish take longer and longer to return and be caught en-masse incoming near the coast when/where returning to spawn.

Jun 05, 2019
More BS articles from the climate alarmist club of fools.
What crap media.

Jun 05, 2019
@Old_C_Code.
More BS articles from the climate alarmist club of fools.
What crap media.
Where was the BS and alarmist content in the above report, mate? It merely reported the observation that warming of the salmon's lakes/rivers meant that more food was available for salmons to fatten up earlier than when water colder. And that earlier fattening meant the salmon migrated toward the ocean earlier than before. And they also mentioned the sensible thing about doing the necessary to protect the ocean food chain sustainability so that salmon and other species survive and flourish to feed themselves and us also. That's just common sense self-preservation forward thinking like any farmer/agriculturist would think to do for the land and water system health sustainability for their own sake and also for the sake of sustainable food source into the longer term. You act/sound like a troll-factory "weaponised stupid" when repeating patently idiotic accusations like that. :)

Jun 05, 2019
LMAO.
I wonder how the "poor" salmon fared during the 1930's when it was just as hot, if not hotter.
http://climate.gi...ing.html

The Chicken Littles must be truly hungry, for the AGW Cult to be feeding them this bullshit.
Gobble up idiots.

Jun 05, 2019
@antigoracle.
LMAO.
I wonder how the "poor" salmon fared during the 1930's when it was just as hot, if not hotter.
http://climate.gi...ing.html

The Chicken Littles must be truly hungry, for the AGW Cult to be feeding them this bullshit.
Gobble up idiots.
Your obviously non-sequitur comment betrays that you didn't read either the article or my response to @Shootist who also like you didn't read/understand the article.

The study found the warming of the salmon lakes increased their food supply and their migration. Period.

The warming lakes (added to all the other environmental indications around the globe) is indication that AGW is real and affecting ecosystems/species which we depend on for food security.

You didn't read/understand what was written; which means you are also a "weaponised stupid and/or bot" programmed with crap by Russian/GOP/Fossil lobby 'troll-factory' operators.

You're a 'point-and-go' stupid/bot, @antigoracle. :)

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