Rainbow Trout vs Steelhead

Ontario Steelhead Fishing, Introduction – Part 2

What is the difference between a Rainbow Trout and a Steelhead?

If you check the Ontario Ministry of Natural Resource’s (OMNR) fishing regulations, you will not find Steelhead listed. Instead you’ll simply find Rainbow Trout. The distinction between Rainbow Trout and Steelhead is often a source of confusion among novice and casual anglers.

Resident Rainbow Trout or Steelhead?

Steelhead are often referred to as “sea-run”, or as is the case in Ontario, “lake-run” Rainbow Trout.

A Steelhead is an “anadromous” Rainbow Trout. In other words, a Steelhead is a Rainbow Trout that migrates from the tributary waters where it hatched, out to sea, or in this case, one of Ontario’s Great Lakes to mature. Once in the large body of water, Steelhead growth rates rapidly accelerate. They are able to attain much larger sizes than would be possible had they remained in their birth stream.

Non-anadromous Rainbow Trout or “Resident Rainbow Trout” on the other hand, remain in their native rivers and streams throughout their entire life cycle and do not migrate out to the Great Lakes. Because of this, Resident Rainbow Trout remain small relative to Steelhead. Steelhead and Rainbow Trout are however genetically the same species of fish.

Steelhead offspring are capable of converting into Resident Rainbow Trout if an event occurs that blocks access to the larger body of water, such as the erection of a dam. Similarly, Resident Rainbow Trout offspring are capable of migrating to a larger body of water if it becomes accessible and/or if conditions in the resident stream become unfavorable.

One parent of each type, Steelhead and Resident Rainbow Trout, can produce offspring of both types.