axonomically, steelhead are related to rainbow trout, which are themselves a desirable catch. But trout live their lives in the same freshwater stream. Steelhead migrate down to the sea, like salmon. After growing big and strong in the open ocean, they return to the stream where they were spawned.

In technical terms, that makes them anadromous. Even more precisely, Oncorhynchus mykiss — a trout that acts like a salmon.