Species Spotlight: Steelhead

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.

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.