A Word from the Watershed: A Steelhead By Any Other Name

By Corrie Aiuto

So the year 2020 is off to a bad start. Much of the world is currently battling the COVID-19 pandemic in one way or another. If you are like me, you are staying home as much as possible, washing your hands until they chap, and hoping your efforts are enough to keep you and your loved ones healthy. You may also be trying to stay positive in the face of overwhelming anxiety and a relentless 24 hour news cycle. If that’s the case, please keep reading because we are going to talk about something else.

In today’s column we are discussing Oncorhynchus mykiss irideus, otherwise known as steelhead. While most fish are caught up in such pedestrian affairs as catching food and avoiding predators, steelhead have larger considerations. This intriguing species has choices. They can, depending on the conditions, remain in freshwater their whole lives as rainbow trout or they can choose a seaward migration and become steelhead.

Conservation of Native Pacific Trout Diversity in Western North America, 2016. Art by Joseph R. Tomelleri.

I recently spoke to Troy Laws of the Oregon Department of Fish and Wildlife and Dale Webb, Vernonia City Councilor and longtime member of the Nehalem valley Izaak Walton League about steelhead. Both men are local watershed and fish aficionados (a-FISH-ionados?).

“Steelhead are fast swimmers and powerful jumpers,” Dale says. “They are also kind of picky eaters, and that makes them a bit of a challenge to anglers.”

Dale explains that their agility and strength allow them to reach areas of steeper and faster flowing waters for spawning and their offspring tend to favor these fast waters, as opposed to salmon, who seek out lower gradient reaches, main stem areas, and even side channels.

“This is their niche in the system,” he says, “Faster waters have more oxygen, but not everyone can withstand the current. They use that to their advantage rather than compete for the side channels.”

Steelhead are typically 5 to 15 pounds but can reach 45 inches in length and weigh up to 55 pounds. There is some debate about whether steelhead are a type of salmon or trout, due to their anadromous abilities (returning from the ocean to spawn in freshwater), but basically steelhead are trout in genetics, salmon-like in behavior, but unlike salmon can live to spawn more then once.

Their life cycle is familiar, as it resembles that of salmon with a few exceptions. Troy explains that summer and winter steelhead make their runs upstream in the summer and winter, respectively, with both types spawning in winter through early spring.

“Summer steelhead are known to run in late spring throughout summer and typically cover much greater distances than their winter counterparts,” Troy said, “They travel as far upstream as they can reach (think mid- and upper Columbia River
Basin and the upper Rogue, Umpqua, Siletz, and Wilson River basins for example), while winter steelhead tend to occupy the lower tributaries of these same rivers and all of the direct ocean coastal streams from the South Coast/California border on up to the Columbia river at the northern end.”

Steelhead life cycle chart courtesy of City of San Luis Obispo.

Females dig nests, or redds, in the loose rock of the stream bed and the eggs, once laid and fertilized by the males, are covered with gravel. Troy also explained that hatching is directly related to water temperature, so eggs could take months to hatch in very cold water but only a few weeks in warmer water. Juvenile steelhead stay in freshwater far longer than salmon, waiting two to five years before migration. When they reach the sea, they grow larger than their freshwater counterparts, change to a more solid silver color with a red or pink stripe, and become steelhead. They return to their natal streams to spawn after two to three years. Some even live to spawn again, making a second or even third ocean journey. Resident rainbow trout live a similar life cycle of spawning and rearing, but they do it all in freshwater habitat.

Dale says he does not know of any resident rainbow trout in the Nehalem and its tributaries, but he confirmed that winter steelhead spawn here. He reported that their numbers look good this year and he was even able to catch and release two or three (in an age long ago, back before the quarantine times).

The fact that not all rainbow trout become steelhead is fascinating. As I researched (from home, in my pajamas, drinking my third cup of coffee) I had to know why some rainbow trout stay in freshwater and some go to sea. According to a study by N.W. Kendall and J.R. McMillan published in 2014, many factors influence which life cycle is triggered: anadromy or residency. These include genetics, the size or growth rate of individual fish, and the environment. More residency is found in summer steelhead, who travel so far inland. Some fish become trapped by physical barriers and being unable to migrate, become resident. Others miss the migration window during their smolt stage, and become resident. There is also some evidence to suggest that resident rainbow trout have a higher fat content than steelhead and perhaps a lack of nutrients prompt fish to seek food at sea.

All of these details mean that steelhead, as a species, have variability. These “choices” allow them to be flexible and to survive; one bad season cannot wipe out the entire stock. Variability, or plasticity, is a crucial component to survival in a changing climate.

Despite this flexibility to stay or go, steelhead still face many challenges and their numbers are declining. Along the Pacific Coast 11 species are listed as endangered or threatened under the Endangered Species Act. While resident rainbow trout are far from extinction due to healthy stocks nationwide, native populations of seafaring steelhead are threatened by disease, high temperatures and loss of habitat due to dams, urbanization, deforestation, stream simplification and land development.

Like salmon, steelhead need our help to restore access to spawning and rearing habitat, stream habitat restoration and to protect our riparian areas and wetlands, from the headwaters to the bay, that keep streams cool and clear. For 22 years the Upper Nehalem Watershed Council (UNWC) has worked toward that end for the benefit of fish and humans. We believe that even in our times of chaos we can find answers that bring us in greater balance with the planet that sustains our lives with abundant provisions.

We here at the UNWC are faithfully working, from home and in nature for now, to continue that effort. We wish you all safety, health, and good spirits until we see you again.


Originally published on 4.2.20 in Vernonia’s Voice.