Hakai Magazine

Sockeye salmon
Geneticists believe river-type salmon, like those in Alaska's Koktuli River, were the first to colonize Bristol Bay, and that they have repeatedly evolved into the lake-type sockeye that now dominate the region. Photo by Hiroya Minakuchi/Blue Planet Archive

A Rare Salmon Type Is in the Crosshairs of Alaska’s Proposed Pebble Mine

The Koktuli River watershed, potential home of the future open-pit mine, is also home to a distinctive river-type sockeye.

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by Ashley Braun

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The sockeye salmon that come from the Koktuli River aren’t like most other fish in Alaska’s Bristol Bay, where a thriving fishery provides nearly half of the world’s wild sockeye. These salmon represent a rare class of sockeye with unique genes and a singular life strategy that sets them apart from the millions of fish that spawn in the rivers and streams that feed into Bristol Bay. Now, Koktuli River sockeye are in the spotlight because the Pebble Mine, a copper and gold mine proposed for southwest Alaska, is slated for the water in which they live.

On Monday, August 24, the latest development arrived in the long and controversial story of the Pebble Mine. The US Army Corps of Engineers (USACE), the agency in charge of permitting the mine, posted a letter officially informing the project’s developer, Pebble Limited Partnership (PLP), that the open-pit mine, as proposed, would “cause unavoidable adverse impacts” to the surrounding watershed, resulting in “significant degradation.”

That determination would be a death knell for the project per the Clean Water Act—unless the company takes appropriate steps to mitigate or offset the damage it will cause to more than 1,300 hectares of wetlands and nearly 300 kilometers of streams, most of which lie within the Koktuli River watershed. In recent weeks, prominent Republicans, including President Trump’s oldest son, Donald Trump Jr., and Fox News commentator Tucker Carlson, have voiced opposition to the mine, feeding speculation ahead of Monday’s letter that the administration might block or delay the project.

Bristol Bay is one of the last places in the world that consistently produces huge numbers of wild sockeye, and the fishery that relies on them contributes US $1.5-billion a year in economic activity. That consistency stems from the region’s diversity: it is home to many different salmon populations and many different kinds of salmon habitat. Each year, the contributions of each to the total catch in the bay varies considerably. And the variation creates resilience—a so-called portfolio effect—that is key to this region’s ongoing productivity, according to Daniel Schindler, a University of Washington ecologist who has studied Bristol Bay salmon for decades. But even among this diversity, Koktuli River sockeye are particularly interesting.

After hatching, most Bristol Bay sockeye swim downstream and spend a year or two fattening up in the region’s abundant lakes before continuing on to the Pacific Ocean. These are the plentiful “lake-type” sockeye. But the rarer “river-type” sockeye—including those in the Koktuli River—don’t have the luxury of lakes to serve as a nursery. Instead, they head out to sea in their first year of life.

Lake- and river-type sockeye differ not only in their survival strategies but in their genes. Furthermore, a growing body of genetic evidence suggests that river-type sockeye are the ancestral form of the species that “acts as a seed source” for establishing new populations in new habitats, says Gordon Reeves, a retired US Forest Service fisheries ecologist. Geneticists believe these more versatile salmon were likely the first to colonize Bristol Bay after the last glaciers retreated, and have repeatedly evolved into the lake-type sockeye that now dominate the bay.

Analyses first published in 2012 by the Alaska Department of Fish and Game (ADFG) suggest that the Koktuli’s river-type sockeye are a separate genetic population, though one that is closely related to three other river-type populations in the Nushagak River, which drains into Bristol Bay. That and subsequent research seems to have flown under the radars of USACE and the US Environmental Protection Agency (EPA) until recently, but it shows that, together, these four populations make up half of the river-type sockeye in the Bristol Bay watershed, says Tyler Dann, an ADFG fisheries geneticist who is also Saint Lawrence Island Yu’pik and grew up in Alaska subsistence and commercial fishing.

Of the 98 populations the state has identified in its genetic analyses in Bristol Bay sockeye, only eight are river-type, he says. Dann adds that they represent an important and unique life strategy among sockeye and are “certainly part of the variability that helps maintain an overall stable and healthy commercial fishery and ecosystem.”

In May, the EPA wrote a letter to USACE calling attention to Dann’s research and Koktuli River sockeye, writing that these river-type fish are “evolutionarily important and distinctly unique within the Bristol Bay watershed and Alaska.”

The distinctions of this rare class of sockeye make the ones in the Koktuli River a potential problem for the proposed Pebble Mine.

According to USACE spokesperson John Budnik, PLP’s path to securing a federal permit for the mine lies in it producing a suitable compensatory mitigation plan. USACE says that for every hectare of wetland and kilometer of stream damaged, the company must make up the difference by restoring, mitigating, or preserving an equal amount elsewhere. But USACE’s most recent stance is that these mitigation efforts must now occur in the same watershed as the damage. And the mine is planned to be built squarely in the largely undisturbed, wetland-rich Koktuli River watershed.

Reeves says that though USACE’s final environmental impact statement for the mine acknowledges the EPA’s focus on the Koktuli salmon, the document goes on to dismiss how the project could undermine the portfolio effect that sustains the region’s broader salmon population.

At the end of July, USACE suggested that the mine would not measurably hurt Bristol Bay’s salmon, citing “the vast breadth and diversity of habitat (and salmon populations).” But this view, says Schindler, is shortsighted.

“It is easy to assume that habitats, and their associated salmon populations, are interchangeable across any river basin,” Schindler says. But that isn’t the case. Lake-type sockeye are not adapted to thrive in the Koktuli River—there is no lake—meaning the Koktuli is an important habitat for these rare river-type fish.

Though river-type sockeye are not necessarily the biggest contributors to the Bristol Bay fishery in a given year, Schindler’s research shows that can change suddenly. That’s why maintaining a mosaic of genes, life histories, and habitats is one way to protect a system already disrupted by climate change, let alone a mine, says Schindler.

“Pretending that we don’t need all the component parts, and that the component parts are not critical to the system, is really an arrogant and misguided perspective,” Schindler says. Any mitigation plan should take into account the diverse populations of Bristol Bay sockeye, both those directly in the mine’s crosshairs and those living downstream, he says.

“Given the unusual life history of Koktuli sockeye salmon and their associated genetics, mitigation would have to compensate for their losses by providing reasonable alternative habitats for those life histories elsewhere,” says Schindler.

Mike Heatwole, a spokesperson for PLP, says the company expects to finalize its comprehensive wetlands mitigation plan within the next month or so. “From our perspective, and in line with the final [environmental impact statement], Pebble will not result in a population-level effect on Koktuli River salmon or any other fish population in the region,” he says.

“We are confident that once it has been finalized, it will be more than adequate to offset the project’s impacts,” he says.

The mining company now has until mid-November to submit its mitigation plan, with a final decision from USACE on whether to approve the Pebble Mine to follow.