Too few young sockeye are surviving as they rear in Lake Washington before going out to sea, and the runs — not to mention the famed salmon fisheries — could peter out in 20 years or so if nothing’s done.
SOCKEYE SMOLTS FACE AN INCREASING HOST OF PREDATORS IN LAKE WASHINGTON (THESE WERE PHOTOGRAPHED IN IDAHO), INCLUDING NATIVE SPECIES SUCH AS CUTTHROAT TROUT AND NORTHERN PIKEMINNOW, AND NONNATIVE ONES SUCH AS SMALLMOUTH, LARGEMOUTH AND ROCK BASS, YELLOW PERCH, AND NOW WALLEYE AND NORTHERN PIKE. (MIKE PETERSON, IDFG VIA NMFS, FLICKR, CREATIVE COMMONS 2.0)
That’s according to modeling put together by Dr. Neala Kendall, a WDFW research scientist, and shared for the first time publicly last night.
“Our analysis suggests that only small numbers of sockeye salmon will persist in Lake Washington under current conditions, much less provide future opportunities for tribal and recreational fisheries,” read one of her slides.
“Maintaining the run and restoring fisheries will be very challenging but not impossible,” it also said.
Kendall was presenting to 50 to 60 anglers and members of the Cedar River Council who’d gathered in a banquet room at Renton’s Maplewood Golf Course on an unusually warm evening for April.
The findings were grim news for the fishermen and state managers, as there are few salmon seasons as popular — or that provide the local economic jolt — as Lake Washington sockeye.
It’s been 12 years since the last one, held in 2006 after “insanely high” ocean survival for that year-class of fish brought home one out of every two smolts that left the lake.
RUB A DUB DUB! THREE MEN TROLL FOR SOCKEYE DURING THE 2006 LAKE WASHINGTON SEASON, WHICH YIELDED THE HIGHEST CATCH IN A DECADE BUT HAS ALSO BEEN THE ONLY FISHERY IN A DOZEN YEARS. (ANDY WALGAMOTT)
Despite the promise and production of the new Seattle Public Utilities hatchery on the Cedar River, returns have only averaged 84,000 since then, with even the best of those years more than 200,000 fish shy of the mark to open the lake.
Aaron Bosworth, the state district fisheries biologist, was also on hand and said that smolt survival is now not only lower than it used to be but well below what it is to the north of the continent’s southernmost sockeye system, 2 to 4 percent versus 16 to 20 percent.
As for why that is, Bosworth said that University of Washington studies have ruled out forage and competition — there’s enough zooplankton in the lake to support the pelagic salmon as well as the huge biomass of longfin smelt.
A big and increasing problem is prespawn mortality on returning adults.
His data showed that between 1995 and 2013, from 45 to 85 percent of the sockeye that went through the locks turned up in the Cedar River. But since 2014 only 20 to 33 percent have. That may be function of warm waters in the ship canal making less-healthy fish more susceptible to disease. With the stock comprised of roughly 60 percent natural-origin fish, fewer spawners produce less eggs overall.
SOCKEYE MANAGERS SAY THAT THE PAST FOUR RETURNS OF SALMON THROUGH THE LAKE WASHINGTON SHIP CANAL (BACKGROUND) HAVE SEEN ABNORMALLY HIGH MORTALITY, WITH 67 TO 80 PERCENT OF THE FISH NOT SHOWING UP IN THE CEDAR RIVER. (ANDY WALGAMOTT)
Still, the “leading theory” now for why the runs aren’t better is predation by native cutthroat trout and northern pikeminnow, as well as nonnative species such as largemouth, smallmouth — Lake Washington was rated as the West’s eighth best for bass by Bassmaster as recently as 2016 — rock bass and perch.
The latter stocks might not eat as many smolts as the former, but they do exacerbate the problem, Bosworth said. With a warming climate, they’ll only do better too, it’s assumed.
Another invasive, walleye, are also now being found in the lake, and earlier this year a bass angler caught but unfortunately released a pike, the second known northern here in the past 15 months.
But sockeye snackers are also getting a helping hand from humanity.
Amy Windrope, who was WDFW’s director for the North Sound region before named acting deputy director for the agency, brought up a factor she’d heard a person in the audience mention: light pollution.
Essentially, between sunset and sunrise, all the bulbs we turn on to light the streets and highways, our sideyards, parking lots and more, create an overhead aura that has benefited the fish-eaters to the detriment of young sockeye as well as Chinook.
Kendall said that the effect has extended the time that salmon smolts are visible through the night, making them more vulnerable to predation and providing fewer hours for them to eat without risk.
Scott Stolnack, a King County watershed ecologist, said data showed that 20 years ago there was a definite period when cutthroat were not feeding, but for the past five years, their stomachs are now full at all hours.
“It’s always dusk for cutthroat,” he said.
Driving home afterwards as night fell on Seattle, that really hit home for me.
As I crossed the bridge between Bellevue and Mercer Island, I looked to the south and saw a particularly bright bank of big lights by the lake. And zipping along Interstates 405, 90 and 5 while illuminated for vehicle safety from above, it was like me and the other cars were smolts, any staters in the shadows cutts.
The question of the night really boiled down to: Do we want to do something about this in hopes of having sockeye fisheries again, and if so, What is that path?
Kendall’s modeling suggests the best way would be increasing survival of the young salmon, and that lifting it to rates of 4 to 8 percent yields a good response.
DR. NEALA KENDALL EXPLAINS LAKE WASHINGTON SOCKEYE MODELING. A MODEL SUGGESTS THAT INCREASING SMOLT SURVIVAL WILL HELP REBUILD THE SALMON’S POPULATION OVER TIME. (ANDY WALGAMOTT)
She did face questions from the audience about how confident she was in her work, which is based on current conditions continuing.
Tom Allyn, vice chair of the Cedar River Council, wanted to know how much increasing survival and other tweaks might cost.
When fellow panel member and sportfishing advocate Frank Urabeck called for a show of support for asking WDFW to crunch the numbers, most if not all fishermen raised their hands.
In other words, for our part we’re not ready to give up on the salmon.
“After having heard how difficult a challenge it will be to restore Lake Washington sockeye sport fisheries, the public attending the meeting last night overwhelmingly voted for us to continue to see if that can be done,” said Urabeck. “This means convincing the Department of Fish and Wildlife and other entities like the Muckleshoot Tribe, King County, City of Seattle, U.S. Army Corps of Engineers, etc., to engage in a feasibility assessment of a sockeye recovery action plan. I hope that my colleagues on the Cedar River Council will work with me to this end.”
Even as the Muckleshoots plan another year of walleye studies in the lake and WDFW biologists will again sample for diet and abundance of spinyrays in the ship canal, when talk centered around whether there were any current plans to actively remove predators — there are not — one fisherman pointed out, “You have a room full of volunteers.”