The North — including the Yukon and Alaska — is warming much faster than the rest of the world due to climate change.
Researchers want to know how that will affect the baby salmon hatching in rivers in the Yukon and Alaska.
A recent study looked at the temperature of the Porcupine River, as well as temperatures in the Teedriinjik, Aniak, Andreafsky, Koyukuk, Takotna and Chena. It found that the warming in the Porcupine River may be enough to limit the growth of Chinook salmon based on the frequency of days and river length which will warm to the upper limit of the temperature range for individual growth.
The Porcupine River connects to the Yukon River at Fort Yukon in Alaska, and flows out to the Bering Sea. Salmon hatch inland in freshwater and migrate out to sea, returning inland as adults to spawn and then die.
Warming in the Chena, Takotna, and Koyukuk may also be enough to limit Chinook salmon growth.
“The warmest years in rivers such as the Chena, Koyukuk, Porcupine and Takotna will likely result in smaller Chinook salmon size at the end of summer due to increased metabolic demand at temperatures above their thermal optima,” reads the study.
However, the study does also state that year-over-year Chinook salmon growth could increase slightly due to the warming in most of the basins it looked at.
Peyton Thomas — a postdoctoral researcher at the University of Colorado Boulder and at the University of Quebec in Rimouski — is one of the lead researchers behind the study.
“So fish, just like us as humans, we kind of operate in like, pretty narrow temperature ranges before we get too hot and stressed out, or we’re, like, freezing cold,” Thomas said.
“And so all of that influences how they’re going to feed or reproduce, whether they’ll be able to escape from predators, and it describes a lot of their behaviour.”
Thomas said she used data from stream gauges, which monitor the temperature of the water, in place across multiple river systems in Alaska and the Yukon. She used this data to inform models which would predict how rivers may warm over time, and how that would affect fish growth.
Thomas also used information shared with her in interviews to help inform the projections of river temperature and salmon growth.
Thomas said she did individual one-on-one interviews and workshops with Yukon First Nations and Alaska Native community knowledge holders at the Arctic Rivers summit in Anchorage in 2022. They helped to identify the species and locations this research would focus on, Thomas said.
The models found that as rivers warm, it may introduce more challenges to salmons at the beginning of their life cycles: the model simulations are projecting that those temperatures are likely to exceed juvenile salmon growth, Thomas said.
“It’s not like they can’t exist there, but populations that are there may struggle a little bit more to to continue to grow,” Thomas said.
Thomas also said that the analysis can help to identify rivers which may remain colder and can act as places of refuge for young salmon, given that there is enough food.
The findings can also identify areas where rivers may become prohibitively warm for young salmon, Thomas said.
At the same time, Thomas stipulated that the results weren’t wholly negative for the Chinook salmon.
“In most of the rivers that I simulated, Chinook salmon were still able to grow pretty much at the same trajectories that they would from previous observations. So at least for juveniles, it doesn’t look too dire.”
At the same time, the research found that other species of fish, specifically Dolly Varden, may benefit from warmer river water. Historically, the temperature of these rivers have been unfavourable for these fish, and simulations of future river warming suggest that the growth of these fish will increase across all the rivers in the study.
After the modelling was complete and results were ready, Thomas shared the results with community members for verification.
“We want to know how the models results align with people’s experiences in individual communities, because we need validation, and obviously, we want the models to reflect real things that are going on in the world,” Thomas said.
She said she spent the past year doing interviews in three communities in Alaska: Aniak, which is on the Kuskokwim River, St. Mary’s on the Andreafsky River, and Elim, on the Tubutulik River.
“We interviewed people like all around the village. So whether they were part of Native councils, Native corporations, whether they were just, you know, hunters or fishers in the village, really looking for everyone’s input,” Thomas said. She said that there are plans to do more interviews as well.
She said she wants the information that comes out of this research to be useful and useable and accessible to communities.
“We’re taking requests from other communities who may be interested in this data, because we can generate reports pretty quickly once we have the draft together for what they should look like,” she said. “So yeah, it’s sort of an iterative process.”
Thomas said that her interactions with Indigenous people across Alaska and the Yukon underlined the importance of Indigenous knowledge.
She remembers hearing about the old stewardship practices of a tribe from the Upper Yukon, creating protective habitats for juvenile salmon, and how the tribe is trying to get the right to do so once again .
“It is so powerful because it’s like it shows that people are obviously already knew that juveniles were really important before we came out with this finding, before all of these other research articles came out about how important juvenile fish are to these areas,” Thomas said.
“Obviously people that live and are from these places know that this is the right way to go in terms of management and stewardship.”
Thomas said she is happy to hear from anyone — from community representatives to community children — who are interested in knowing more about the project.
Thomas said she’s transitioning into the role of an assistant professor at the University of Colorado Boulder, and people can reach her through her email address.
“I’m like, definitely excited about having more opportunities to work with individual communities, to do more monitoring and, like, use whatever skills I have to be able to facilitate community interest in fish research.”
Contact Talar Stockton at talar.stockton@yukon-news.com
