How to Identify Baby Steelhead from Other Similar Species

September 24, 2021

Steelhead are a curious, delightful encounter that you could come across during your fishing trips. The reason why it’s a curious encounter lies in the fact that they come out of the same eggs as rainbow trout.

However, they are anadromous creatures, meaning that, just like salmon, they live most of their life in the ocean, not in river streams. This is mainly why they’re often confused for different fish species. Steelhead babies are especially liable to that confusion. 

Knowing how to identify a baby steelhead could be a bit tricky as they share many features with other trout and salmon species.

In this post, we’ll discuss the most notable features of baby steelhead as well as the differences between the steelhead parr and other river-found parr. Stick around. 

How to Identify Baby Steelhead

Steelhead trout begin their life cycle in a freshwater stream. When they mature, they migrate to the ocean and only swim back to their birthplace during the spawning period.

From around late October to early May, spawning females search for areas in the river where they could find moderate-sized gravel. Thereafter, they dig a pit underneath it to lay their eggs. The males then fertilize those eggs. After a month, they become eyed eggs ready to hatch. 

Adult steelhead have a pretty distinctive appearance. They are silvery, streamlined with a red stripe running along their sides. In the ocean, adult steelhead gain a metallic head color that looks like shiny steel, which is why they are called steelhead.

On the contrary, differentiating juvenile steelhead from those of rainbow trout and salmon trout isn’t an easy feat. 

A baby steelhead goes through multiple metamorphic stages before it becomes a smolt. During those stages, it changes its external features and habits multiple times until it becomes an adult. 

So, to put a clear line between all those confusing species, you will need to pay attention to four differentiating aspects:

  • Appearance
  • Size range
  • Eating habits
  • Typical behaviors

Appearance

Steelhead

During the life cycle of a trout, it changes its external appearance multiple times to adapt to environmental changes and hide from predators. A newly hatched juvenile trout would pass through three stages before maturing: 

  • The alevin stage
  • The fry stage
  • The parr or fingerling stage

The alevin stage is the second life stage for a steelhead. Alevins are the newly hatched steelhead babies. They can’t depend on their surrounding environment for feeding, which is why they are born with a big, red feeding sack attached to their bodies.

Alevin steelheads grow to become a fry within three months to a year. A fry can swim around in the cold fresh water and feeds on zooplankton. They have spots on their sides to help them camouflage and hide from predators.

If a fry was able to survive for long enough, it grows into the size of a finger. They are then called parr fish or fingerlings.

You could easily trace the differences between steelheads and other species by looking closely at those different developmental stages. 

Steelhead vs Salmon Trout

A baby steelhead is most distinguishable during the parr stage when it starts to develop some of its prominent features. Unlike Chum and Sockeye fingerlings, steelhead have spotted dorsal fins and a red lateral line on their sides.

In addition to that, a baby steelhead doesn’t have red or yellow marks on its throat, and it doesn’t have teeth on the base of its tongue.

The difference is not as easily distinguishable when we’re talking about Coho salmon, Chinook Salmon, or Cutthroat salmon. 

All of the four species have parr marks across the lateral line on their scales and similar coloration patterns. However, if you examine a steelhead closely, you will find that it has a white mouth with white gums and a tail with many spots aligned in distinct rows.

Steelhead vs Rainbow Trout

Rainbow Trout Swimming

If you’re trying to identify whether a baby trout is a steelhead or a salmon, checking the colors and patterns on the scales might be enough. However, external features alone aren’t enough to tell a baby steelhead apart from a baby rainbow trout.

Steelhead and Rainbow trout are essentially the same. They carry the same scientific name (Oncorhynchus mykiss). What’s even more confusing is that a rainbow trout could hatch out of a steelhead egg, and a steelhead could hatch out of a rainbow trout egg. 

Rainbow trout gain the features of a steelhead only after migrating to saltwater. On reaching an estuary, they undergo irreversible changes in their physiological construction adapting to their new environment. So, at birth, a rainbow trout and a steelhead trout would have the same colors and patterns. 

Size Range

Salmon species are known for their large bodies in comparison to other anadromous fish. Some of them are as large as 55mm fingerlings. You could easily distinguish Coho and Chinook from steelhead by looking at the size alone. 

Despite that, some salmon trout stay as small as 39mm during their parr stage. Chum, Sockeye, and Cutthroat cannot be differentiated from steelhead only by looking at their size difference.

Surprisingly, when comparing sizes, you could find some fine differences between baby steelheads and baby rainbow trouts. Some people might argue that a baby steelhead has a thinner body and a disproportionate head in comparison to that of a rainbow trout. 

Eating Habits 

Steelhead is known to be a carnivorous fish that could eat almost anything in its environment such as: 

  • Zooplanktons 
  • Small insects 
  • Fish eggs 
  • Small fish

Due to their fragile birth state, baby steelheads tend to only pick up zooplanktons and other microorganisms within their surroundings.

In comparison, young salmon mostly eat small insects that come across the river stream. Their diet includes:

  • Mayflies 
  • Blackflies
  • Stoneflies 
  • Riffle beetles
  • Caddisflies

Typical Behaviors

Steelhead

Even though they’re almost the same, steelhead trout and rainbow trout lead a completely different life. 

Because steelhead will eventually move to a richer, more dangerous ecosystem, they tend to be more agile than most rainbow trout. 

After one to three years of living in a river, the parr steelhead grow into smolt and migrate upstream to adapt to their new lifestyle.

Due to their huge range in maturing age, you would often find a varied population of steelhead across many rivers.  

Additionally, they’re known to travel for thousands of miles across the western coast of North America. Some of them are found as far as Japan coasts.

In addition to their difference in appearance, steelhead can live up to eight years. Salmon species could only live up to five years on average. They also have the ability to spawn multiple times.

Frequently Asked Questions

Steelhead trout species are some of the most popular species in the world, which is why they carry huge economical and cultural importance. This is also why there are plenty of questions that revolve around steelhead. 

Here are some of the frequently asked questions about steelheads:

What do steelhead eggs look like?

Steelhead spawn a range of colored eggs between red and orange. They’re round in shape and resemble other salmon eggs. They could also be as big as 3/8 inches in size.

Is steelhead an endangered species?

Steelheads aren’t an endangered species. However, many of them are currently subjected to different threats. As we continue to build dams across the river banks, we prevent many of them from going through their natural life cycle.

Because steelheads are an extremely special type of rainbow trout, some of them are protected under the Endangered Species Act.

Is there any difference between hatchery steelhead and wild steelhead?

By carefully examining hatchery and wild steelhead, you’ll find that most of the hatchery steelhead are missing their adipose fin, which is a small sack found on the back of a fish and is used for food storage purposes.

The reason why they are missing is that hatcheries clip them from juvenile fish to identify them from wild steelheads.

Where can you find steelheads?

Even though steelheads are natives of the western coasts of North America, they’re often found in many states. You could also find them on every other continent except for Antarctica. 

Depending on their developmental stage, you could find them in many rivers and estuaries.

In Conclusion

Steelhead fish are distinct among many other types of fish in the Salmonidae family. Their silvery grayish color and lateral red stripes add to its aesthetic value. They’re well known for their high jumps while going up steam during their migration season. 

Learning how to identify baby steelhead is a demanding task that requires paying attention to details. They share many of the characteristics of both rainbow trout and salmon trout, which makes them difficult to identify on the spot. 

Amidst those similarities, though, you could find some recognizable differences in their scale patterns, colors, and shapes.

Happy Hunting!

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