The 2020 chinook spawning season is drawing to a close, and we’ve seen a lot of fish spawning in Issaquah Creek! The hatchery concluded the chinook spawning season on Oct. 13 with the fourth weekly egg take of the run. Hatchery staff and volunteers, all wearing masks, socially distanced, spawned a season total of 881 chinook hens and bucks, and collected 1.8 million eggs. Disappointingly, this number fell short of our goal of 3.2 million, so the Soos Creek Hatchery has provided 1.5 million extra chinook eggs to the Issaquah Hatchery for a total of 3.3 million eggs.
For the season, our hatchery saw roughly 2,348 chinook (35 natural origin) jump up the fish ladder and into the holding ponds. For the Greater Lake Washington Watershed, more than 12,000 chinook were counted entering the fresh water at the Ballard Locks. Some of those salmon headed to other streams to spawn, and many spawned downstream of the hatchery in Issaquah Creek.
Gallery: Spawning Chinook, 2020
Due to our warm, dry weather this fall, it was feared that a number of the chinook would not make it back to their spawning grounds. Those that did arrive were overwhelmingly male: about 75 percent, as the females are preferred by predators such as seals, sea lions and orcas.
Although the number of fish arriving at the hatchery this year was fewer than average, the hatchery released 51 chinook upstream above the weir to spawn in the upper reaches of Issaquah Creek. These were fish that were not ripe by the final spawning day at the hatchery.
The good news is that the weekend rains brought lots of coho upstream! At least 1,200 are currently trapped in the holding pond as of this writing. Coho spawning is expected to start in late October and continue through mid-November. Let’s route for big numbers this year!
Oct. 9, 2020: Hatchery staff and volunteers have been spawning our chinook salmon since Sept. 22. After the third spawn, the hatchery has collected just 1.7 million eggs. This year’s goal is 3.3 million eggs, so this may be difficult to achieve.
While the chinook run is bigger than average this year, the vast majority of fish returning to the hatchery are males. The reason for the lopsided return is unknown, but we do know that predators generally prefer to feed on females with their tasty and nutritious eggs. WDFE staff will be picking up chinook eggs Tuesday, October 13 from the Soos Creek Hatchery to supplement our harvest and reach our goal for egg production — as they did last year as well.
Meanwhile, Issaquah Creek is full of spawning chinook below the hatchery, and coho are starting to return as well — although they won’t start spawning until later in October. We have also seen four sockeye in the creek so far.
The unseasonably warm and dry weather this fall has kept fish in Lake Sammamish for the last couple of weeks as they wait for rain to migrate upstream. The next storm should bring an influx of new fish to the hatchery.
One of the miraculous facets of a Pacific salmon’s life is its death. All Pacific salmon die after they spawn. In doing so, they enrich their home stream with their harvest of years of nutrition on the high seas. This chinook will feed the local ecosystem, and perhaps even its progeny when they emerge from the gravel in 4 months time.
Betcha Didn’t Know This:
The sharp-eyed among you may note that this chinook’s tail has been cut off. This indicates that a Fisheries Biologist has sampled, measured and counted this fish. Severing the tail ensures that this fish is not counted more than once.
Did you know that ducks are not vegetarians? This photo of mallards feasting on a dead salmon was also taken today on Issaquah Creek.
Spawning salmon returning from the ocean to the Greater Lake Washington Watershed and our own Issaquah Creek are getting a helping hand to get past predators at the Ballard Locks. That is where many Issaquah chinook and coho – squeezed into a small space to navigate the fish ladder into fresh water – are getting waylaid and devoured by hungry harbor seals.
And it is not just the adult salmon that become dinner for seals. Smolts migrating from the Issaquah Salmon Hatchery out to the ocean spend several months just below the locks as they adapt to saltwater, and many become snacks for the resident harbor seals. The U.S. Army Corps of Engineers, in partnership with non-profits and tribes, is experimenting with a new noise-making technology that will deter salmon-fishing by seals and potentially improve the salmon survival rates.
According to the Seattle Times:
A new gadget is being tested at the locks, intended to startle seals to deter them. The so-called Targeted Acoustic Startle Technology, developed by scientists from the Sea Mammal Research Unit at the University of St. Andrews, is marketed by GenusWave Ltd. based in Edinburgh, Scotland. The device was made for use at fish farms, to keep seals away from net pens. The device is housed in a metal canister that looks like an upscale water bottle, and produces a sound played through two underwater speakers at randomized intervals. The sound it makes is not particularly loud or unpleasant … to a person. The acoustic technology replaces conventional, loud noisemakers that seals just get used to. The sound made by the startle device provokes a flight response — a fundamental mammalian reflex — without causing harm to the seal, or bothering salmon.”
Updated from the original post on Friday, September 25, 2020: Some of the salmon in this year’s return are sporting a highly visible plastic string, telling any observer there is something important about this fish. In particular, this Chinook was captured at the Chittenden Locks by the Muckleshoot Indian Tribe, equipped with an internal tag (acoustic transmitter) that will ping multiple receivers in fixed positions as the fish makes it way from the Locks, through the Lake Washington Ship Canal, Lake Washington, the Sammamish River, Lake Sammamish, and finally, Issaquah Creek. The main purpose of tagging the hatchery fish is to document survival during their migration from the Locks to the hatchery. The last couple of years we have noticed a difference in numbers between the Lock counts and what shows up at the hatchery so we are trying to find out if and where we are losing fish.
Wednesday, Sept. 23, 2020: The forecasted chinook return to the Issaquah Salmon Hatchery was about 4,000 fish. The number counted through the Chittenden Locks was 12,780 as of 09/20. What?!? Historically, 50 to 70% of the fish counted through the Locks make it to the Issaquah hatchery. Some of the chinook are headed to the Cedar River, where they are considered an endangered population, but most are headed our way.
Another brush with reality: this time, the males outnumbered the females almost 3 to 1! We know that pinnipeds (and our beloved orcas) prefer female chinook – they are loaded with fat and protein-filled eggs, but this season that tendency is extreme.
The WDFW set a pretty high bar to assure the safety of the staff and volunteers at the spawning shed, but the shortfall of female chinook made it a short day, resulting in 328,000 fertilized eggs — a small but significant step to the 3,200,000 chinook egg goal for the year. The holding pond is full, the creek is full, so we are on a good path to meeting the goal.
What can we conclude from this?
Salmon return forecasting is even tougher than weather forecasting. And, we need to get good data on where the female attrition is happening, and whether something can be done about that.
Please note that the WDFW is not allowing tours on Tuesdays, spawning days, as keeping staff, volunteers and possible visitors safe is paramount.