A dead sockeye salmon, dried in an interesting shape, in the Bristol Bay watershed on August 9, 2018. (Mary Catharine Martin | SalmonState)

A dead sockeye salmon, dried in an interesting shape, in the Bristol Bay watershed on August 9, 2018. (Mary Catharine Martin | SalmonState)

The Salmon State: “Surfing the salmon wave” in Bristol Bay

Habitat diversity produces salmon diversity — and well-nourished predators

By mid-August Bristol Bay’s river systems are choked with fish, but early July, when most of the bay’s sockeye salmon are fighting their way in from the sea, is another story. What’s a bear — or a grayling, trout or gull — to do?

The short answer is: start surfing.

The diversity within Bristol Bay’s landscapes and rivers means two salmon that arrive at the mouth of the same river system at roughly the same time might spawn weeks apart, depending on their ultimate destination. It’s a phenomenon researchers call the salmon wave — and the predators that follow the salmon are its surfers.

Colder streams’ salmon spawn first. Often, those streams are smaller. They hold relatively few fish, but, because of when those fish are available, are “disproportionately important” to the ecosystem as a whole, said University of Washington Professor of Aquatic and Fisheries Sciences Daniel Schindler, who’s been studying salmon in Bristol Bay’s Wood River watershed for two decades through the university’s Alaska Salmon Program.

“A single salmon to a predator in the middle of July is way more important than a single salmon to that predator in the middle of August,” Schindler said. It can be easy to overlook the importance of tiny streams when developing, he said, but “it’s the network of sites that’s important for ecological function.”

After the colder streams, salmon whose natal streams are warmer spawn mid-August to September. Last of all in the Wood River system, salmon spawn on lake beaches starting in September. All of those spots have genetically distinct salmon populations. And throughout it all, bears and other predators “surf the salmon wave,” moving from creek to creek to get salmon protein for the longest span of time possible — and bettering their chances of surviving to the next year.

High-grading

In times and places bears can find lots of salmon — like August in Bristol Bay — they tend to high-grade for the most nutritious parts, frequently eating just the brains of the males (which are big and fatty) and the eggs from the females.

“Out here, in a typical small stream, (predators) aren’t limited by how much salmon is available — they’re limited by their ability to process it,” Schindler said.

In the spring, in contrast, a person walking along a riverbank might see bear scat full of the backbones of salmon. Bears have found and eaten the old, dried up carcasses, so the “salmon wave” can last through the spring, even if live salmon don’t.

In some places in Alaska, Schindler said, fish spawn from mid-May all the way to February — though, of course, in far-reduced numbers outside the main spawning months. Bears and other predators surf those salmon waves, too.

Climate, and the way it’s changing, also matters. Steep streams tend to be cooler because they’re getting snowmelt. Snow cools them for less time following dry winters than snowy winters, which means more streams across the river basin are similar temperatures. This has the potential to shorten the duration of the “salmon wave.” Mountainous, glacier-filled landscapes like Southeast Alaska can offer even more complexity of habitat than a place like Bristol Bay, which has an effect on those that prey on salmon. The hypothesis of a paper Schindler and former PhD student Jonny Armstrong — now assistant professor at Oregon State University’s Fish and Wildlife Department — are talking about is that places with the most “geomorphic and hydromorphic complexity” (the most diversity of land and water) have the biggest bears.

This summer was a stellar one for Bristol Bay, with a record return of more than 62 million sockeye salmon to the entire region by Aug. 2 and more than 7.5 million making it up the Wood River system alone. In addition to sheer abundance, however, what’s equally important to a system’s overall reliability for salmon-eaters, humans included, “is the diversity of salmon that come back to watersheds,” Schindler said. “And that diversity is produced by habitat diversity.”


• Mary Catharine Martin is the communications director of SalmonState, a nonprofit initiative that works to ensure Alaska remains a place wild salmon thrive.


A bear catches salmon at Middle Creek on Admiralty Island of Southeast Alaska on a recent year. Research from Bristol Bay and other Alaskan salmon strongholds shows that bears and other predators “surf the salmon wave,” moving from stream to stream depending on when the salmon are spawning. A diversity of spawning times depends in large part, on a diversity of habitat. (Mary Catharine Martin | SalmonState)

A bear catches salmon at Middle Creek on Admiralty Island of Southeast Alaska on a recent year. Research from Bristol Bay and other Alaskan salmon strongholds shows that bears and other predators “surf the salmon wave,” moving from stream to stream depending on when the salmon are spawning. A diversity of spawning times depends in large part, on a diversity of habitat. (Mary Catharine Martin | SalmonState)

More in News

(Juneau Empire file photo)
Aurora forecast through the week of Nov. 10

These forecasts are courtesy of the University of Alaska Fairbanks’ Geophysical Institute… Continue reading

Students arrive at Thunder Mountain Middle School on the first day of school Thursday, Aug. 15. The school now houses all students in grades 7-8, who were in two middle schools last year, and the students at Thunder Mountain last year when it was a high school have been consolidated into Juneau-Douglas High School: Yadaa.at Kalé. (Laurie Craig / Juneau Empire file photo)
Report: 11 high school fights during first quarter of school year, up from 3 each of past two years

Consolidation seen as possible factor; middle school incidents more typical compared to recent years

People gather outside Resurrection Lutheran Church as it hosts its weekly food pantry on Tuesday afternoon. (Mark Sabbatini / Juneau Empire)
Resurrection Lutheran Church leadership dispute intensifies with accusations of assault, theft, sabotage

Pastor removed, lawsuit lingers as competing groups try to continue worship services, food pantry.

Nick Begich, center, the Republican candidate for Alaska’s lone U.S. House seat, talks with supporters during a meet-and-greet Oct. 12 at the Southeast Alaska Real Estate office near the Nugget Mall. (Mark Sabbatini / Juneau Empire file photo)
Updated vote counts show Begich, repeal of ranked choice voting likely to prevail

Most ballots uncounted on Election Day have now been tallied, with final results due Nov. 20.

Letters of support are posted to the window of the Kachemak Bay Family Planning Clinic on Tuesday, Nov. 12, 2024, following a shooting incident on Monday, Nov. 11 at 5:45 a.m. in Homer. (Delcenia Cosman/Homer News)
Man arrested for three shooting incidents at reproductive clinic, recovery organization in Homer

Kachemak Bay Family Planning Clinic was targeted twice Monday, suspect cites “religious beliefs.”

A sign welcomes visitors to Hoonah on Aug. 7, 2021 just outside the Icy Strait cruise ship port. (James Brooks/Alaska Beacon)
State commission approves new Xunaa Borough government in northern Southeast Alaska

Area would include Hoonah and much of Glacier Bay National Park, exclude three nearby small towns.

Juneau Assembly Member Ella Adkison (center) helps state Sen. Jesse Kiehl load donated groceries into a van on Saturday during a food drive at Super Bear IGA Supermarket hosted by the Juneau Central Labor Council. (Mark Sabbatini / Juneau Empire)
Nonprofits say need is high as collections for annual Thanksgiving events approach

Food bank, other agencies say number of people seeking help is rising due to cost, other factors.

(Michael Penn / Juneau Empire file photo)
Police calls for Saturday, Nov. 10, 2024

This report contains public information from law enforcement and public safety agencies.

Gov. Mike Dunleavy poses with then-President Donald Trump during a refueling stop by Air Force One at Joint Base Elmendorf-Richardson in February of 2019. (Official White House photo)
Update: Dunleavy and Dahlstrom plan, cancel live Tuesday night announcement as Trump post for governor rumored

Dunleavy being considered for Interior secretary; also backs Trump on eliminating Dept. of Education

Most Read