2 Tiny Rivers, 18 Different Steelhead Life Histories

Most of us are probably pretty familiar with two main life histories of steelhead:

  1. Hatch in hatchery, rear in raceway ponds for about a year and a half old, get released, head quickly for Puget Sound and the North Pacific, mostly return to hatchery a year and half later, with some spending a second year in the salt.
  2. Hatch in the gravel, spend two to three years in the river, head quickly for Puget Sound and the North Pacific, mostly return a year and half later, with some spending a second year in the salt.

Turns out there are a few more possibilities — at minimum a dozen and a half in two small streams on the Washington side of the central Straits.

That’s according to federal researchers based at the National Marine Fisheries Service’s Montlake science center, as well as tribal and private biologists.

They placed passive integrated transponders in young winter-runs in the West and East Twin Rivers between Port Angeles and Sekiu and monitored their movements over time.

“Movement patterns revealed at least 18 life histories of steelhead O. mykiss with variations in age and seasonal migration of juveniles, juvenile use of the ocean prior to migration, years spent in the ocean, season of adult return, and iteroparity,” the authors state in the abstract of their paper, published in August.

By the way, you are iteroparitous — that is, like steelhead you have the ability to make multiple spawning runs over your life.

THE TWIN RIVERS ARE ONE OF THREE INTENSIVELY MONITORED WATERSHEDS IN WESTERN WASHINGTON. (RECREATION AND CONSERVATION OFFICE)

THE TWIN RIVERS ARE ONE OF THREE INTENSIVELY MONITORED WATERSHEDS IN WESTERN WASHINGTON. (RECREATION AND CONSERVATION OFFICE)

One of the authors notes that while 18 is just half of all the life histories observed in two large California and British Columbia systems, the diversity is “not bad” for rivers all of 13 square miles or so.

“… Coolest of all, is that we documented two cool life histories,” adds John McMillan of Trout Unlimited. “Some fish left the river at age-1 during the summer as parr, not the spring when most fish smolt, and then returned in late-fall before eventually migrating out to the ocean for good at age-2. Sound like a half-pounder? Further, some age-0 fish (fry) migrated to the ocean, though none were documented to survive to adulthood. More remarkable, about 1% of those age-0 migrants left one of the Twin Rivers, entered the ocean and then swam up the other river. A few fish even then returned back to the ocean and swam up the river from which they first came. We are not aware of this behavior being previously documented, but it is likely the same behavior is occurring in other watersheds. Regardless, those are some indecisive fish. Reminds me of Goldilocks.”

Steelhead as well as coho in West and East Twin Rivers and Deep Creek to the west, are being intensively studied by a number of outfits, including NMFS, EPA, WDFW, Department of Ecology, state Salmon Recovery Funding Board, Lower Elwha Klallam Tribe and Weyerhaeuser.

Starting in 2004, instream restoration projects began in East Twin and Deep, with West Twin as a control, and according to a grant proposal last year, “Preliminary results suggest some small improvements in pool habitat and small increases in Coho and steelhead adults in East Twin and Coho adults in Deep Creek, relative to West Twin.”

However, it’s felt that more time is needed for the habitat work to take effect.

In the meanwhile, the work is yielding new insight on winter-runs themselves.

“The study underscores that there really is no normal steelhead, and that frankly, it appears that the way we define a steelhead is more complex than ever,” notes McMillan.

And here you thought getting them to bite was tough enough!

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