How a Hot Summer Could Be Deadly for Salmon

Coho fry are rescued from pools that had become disconnected from the Hoh River.
Coho fry are rescued from pools that had become disconnected from the Hoh River.

After a winter of record low snowfall and Gov. Jay Inslee’s May declaration of a statewide drought, treaty tribes in western Washington are concerned about high water temperatures, low flows and pre-spawn mortality in returning salmon.

“This drought will have catastrophic, far-reaching effects for many years to come,” said Scott Schuyler, natural resources director for the Upper Skagit Tribe.

By May a lack of water had stranded coho, cutthroat and steelhead on the Olympic Peninsula and coast.

Some rivers, such as the Stillaguamish, are setting low flow records every day.

Temperatures higher than 60 degrees are bad for salmon, because pathogens such as ichthyophthirius multifiliis (ich) and columnaris (gill rot) thrive in warm water. The diseases spread more quickly when the rivers are crowded by low flows, and can lead to increased pre-spawn mortality.

Low Snowpack

“We’re not a little below minimum snowpack; we’re a lot below minimum snowpack,” said Jamestown S’Klallam Tribe’s natural resources director Scott Chitwood. “Fish need to get from Dungeness Bay to their spawning grounds about 15 miles upriver and they’re going to have a hard time doing it if we don’t help.”

The Nisqually Tribe is expecting the lack of snow in the Mashel watershed to have a detrimental impact on salmon.

“Without the snowpack we were expecting, I’m not sure how much water we’re going to have in the ground for the creek come August,” said David Troutt, natural resources director for the tribe.

Crowded Rivers

By early June, the Nisqually was already seeing temperatures around 63 degrees, which is problematic for salmon survival.

“In addition to warm water, which could cause pre-spawn mortality of returning chinook salmon, we’re expecting a massive return of pink salmon, which would limit oxygen and habitat available for returning chinook,” Troutt said.

Pink salmon, which return in odd-numbered years, are expected to exacerbate already stressful conditions for fish throughout the region.

Low Flows

On the Skagit River, Schuyler said the drought threatens the future sustainability of salmon runs.

“As fish return this year, there’s no water for them, the available spawning habitat becomes severely limited, and all the salmon species are competing for the remaining spawning areas that haven’t been dewatered,” he said.

In the Skagit River watershed, some water can be stored behind the hydroelectric dams on the Baker River and mainstem Skagit, but that doesn’t help the tributaries.

“The tributaries are where much of the coho spawning occurs,” Schuyler said. “When those are dry, we lose that habitat, and all the species have to compete for the same little patch of gravel in low flow areas of warmer water.”

Reduced Harvest

Effects of the drought were seen during the Upper Skagit Tribe’s spring chinook fishery.

“Chinook are returning later, with no high water flows to bring them in,” Schuyler said. “A secondary effect is that the low water decreases our fishery efficiency and our boats cannot maneuver.”

To access harvestable fish, the tribe is considering future fisheries using dip nets, a less efficient method than gillnets.

“People have high expectations for these fisheries, but this extremely low water is going to affect where, when and how we access fish.”

On the coast, Joe Gilbertson, fisheries biologist for the Hoh Tribe, said that fisheries managers are talking now about what management strategies might be needed in August and September for returning adult fish.

“We saw the lowest flows ever recorded in 50-plus years of records during several days of last September,” he said. “It was a bad year for coho smolts last year and we’re still compiling the data, but it’s not looking good for this year either. You combine that with poor ocean feeding conditions present and it’s looking bad for coho in the future.”

Shared Concerns

As elsewhere, potential problems on the Nooksack River – where temperatures already run high – include pre-spawn mortality, increased stranding of fish and disconnecting of side channels.

“It’s not uncommon for us to find individual pre-spawn mortality in a normal year. This could be a situation that’s worse than usual,” said Ned Currence, biologist for the Nooksack Tribe. “I expect the drought will affect spawning distribution.”

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