Species Spotlight: Steelhead

Mark Darnell

Author: Scott R. Bowler  |  Published: April 20, 2022  |  Category: Species Spotlight

The long & short life history of Oncorhynchus mykiss

Did you know that the fish we call steelhead and the fish we call rainbow trout are essentially the same fish? They are both Onchorhynchus mykiss – just different manifestations of this iconic species.

The differences between the two forms of O. mykiss are dependent upon their origin story and their habitat.

Both forms of O. mykiss inhabit several of our eastern Oregon rivers, notably the Deschutes, and especially the John Day, living and spawning throughout these river systems. The John Day River is the second-longest undammed river in the Lower 48 states, and drains a huge watershed area, rising primarily in the Blue Mountains. This relatively pristine and diverse watershed, with its many tributaries, is absolutely vital to the success of both steelhead and rainbow trout.

 

fact

Young Horny Toad Lizard

Young Horny Toad Lizard

In the summer these lizards begin foraging for food as soon as their body temperature rises as the heat of the day increases. They feed on slow-moving, ground-dwelling insects. In the fall they hibernate by burying themselves in the sand.

Latin name: Phrysonoma platyrhinos

voices

John Cunningham, ONDA member and volunteer

John Cunningham, ONDA member and volunteer

Restoration is hard slow work. It takes hold, or it doesn’t, in fits and starts. The immensity of the need can be discouraging, but we must carry on. I am so thankful ONDA carries on.

watch

Time Lapse: a night at Canyon Camp in six seconds

Time Lapse: a night at Canyon Camp in six seconds

Rainbow trout Steelhead
length: 15-21” long or so 32” long or more
weight: up to a few pounds up to 35 pounds, but often smaller
catchability: generally pretty easy generally pretty difficult
ocean-going: no yes

The early life cycles of both fish are initially similar, beginning with eggs laid,fertilized and matured in a nest structure—the “redd”—excavated in the river gravels and cobbles by the female.

Two key factors are crucial to young fish development:

  1. cold, clear, well-oxygenated water. A stable cold temperature reduces the heat stress that can come with low water flows.
  2.  low “scour rate.” Scour refers to a specific form of erosion, and the key is to protect the redds from large flood events.

Both of these requirements for successful spawning come as a result of a reasonably stable landscape, which is characterized by:

• relatively steady flows, like the spring and aquifer fed Deschutes
• well-vegetated stream banks to shade and cool the water, common in the upper reaches of the John Day
• plant material to provide food for aquatic invertebrates on which they feed, common in the Deschutes and the John Day
• natural meanders, big rocks, and plenty of large woody debris to slow the flow and offer protection to young fish, especially common in rivers without dams to impede debris flow, such as the John Day

From alevin to smolt

The young fish have several names at different stages, depending upon their level of maturity.

First, they are an alevin, a tiny fish with the yolk sack still attached, who mature into fry, and later into smolts. The smolts of both trout and steelhead grow well initially in freshwater, where they eat insects and other aquatic foods, but must also avoid predation. Steelhead young grow fast, yet can remain stream bound for up to three years. At this stage, it can be close to impossible to tell them from young trout.

Head to the sea, or stay in the stream

At some point, steelhead smolts feel the call of the ocean, and this is where their life stories dramatically diverge.

As they migrate downstream, steelhead must pass several dams in the Columbia River to get into the ocean. Once there, the abundant marine food supply enables them to quickly grow quite large. Adult steelhead spend up to seven years in the ocean, and upon reaching spawning age will migrate back upstream, once again pass over the several dams that stand in their way.

Meanwhile, their stream-bound rainbow cousins are limited in the diversity of their habitat, especially regarding abundance of their food supply, and they just cannot grow as fast or as big. Life in a smaller stream also means that they are more likely to suffer to predation, and more vulnerable to heat increases, flooding or low water stresses, plus all of the other threats inherent in their more proscribed habitat.

You might wonder why all O. mykiss babies don’t just opt for the anadramous (ocean-going) lifestyle and migrate. Genetics comes into play: a fish spawned from an anadramous mother will most likely become an anadramous adult. And, habitat plays a role: the larger the stream the fish are spawned in points to them becoming larger, likely anadramous, steelhead. This is because larger streams and tributaries tend to be more resilient, offer a more diverse habitat, provide more food and better protection, thus creating larger, more likely to be anadramous, fish. Conversely, smaller tributaries give rise to smaller fish, offering a home to the rainbows who stay put.

If you want to have more steelhead, the short answer is to protect and enhance the quality of their habitat and ensure that they can spawn in larger streams.

Juvenile steelhead, Bridge Creek

Bridge Creek is federally designated critical habitat for steelhead, and a good place to go if you want to see the excellent results of several years of volunteer work and happy, productive beavers. This creek is currently proposed for overlapping protection in pending legislation that would create a national monument at Sutton Mountain and under the River Democracy Act.

Ben Goldfarb

Giving native fish a fighting chance

Any number of streamside activities, including water withdrawals, widening channels, construction, agricultural chemical use and floods, can have a negative impact on these fish.

To address these issues, ONDA has designed and implemented several critical projects to restore streamside habitat in high-priority desert locales. In particular, our expansive riparian tree planting efforts not only provide direct improvements to desert waterways for fish but also attract one of the most valuable and prolific improved fish habitat creators: beaver.

Beaver are consummate hydrologic engineers and habitat creators that, unfortunately, were once nearly eliminated from this landscape. But, there is good news: beaver are happily increasing their range again now, spreading throughout the John Day River Basin, thanks in part to ONDA-led habitat restoration projects. At the same time, ONDA advocates are making sure that the desert creeks and rivers that are important to steelhead are protected, through measures like the River Democracy Act.

Here are three ways you can look out for these mighty fish:

  1. Advocate for strong protection for desert rivers and streams
  2. Donate to support conservation work
  3. Volunteer for a riparian restoration project

Thank you! Your help is key to ensuring these fish have the cold, steady water and diverse habitat they need.