By, the end of the year they may have reached five inches in length, and by their second birthday seven inches or more. At this stage, the steelhead parr are indistinguishable from the parr of freshwater rainbow trout that will never go to sea. But the following year, when they are seven to ten inches long, the steelhead parr become smolts. While sea-run cutthroat trout tend to remain in tidal waters close to the estuaries of their natal rivers, steelhead shoals will frequently travel a few hundred miles from their home river in search of marine foods. Some steelheads tagged as smolts in rivers in British Columbia have been reported from the seas around Kodiak Island in Alaska, and others have been reported by commercial fishing boats in mid-Pacific up to 2,500 miles away from their natal rivers.
Some rivers have a reputation for producing big steelheads, others produce smaller fish.
Even though they are all steelheads, the pattern does suggest that each river system has its own variety of steelhead. Hence the greater size of these fish. However he also argued that the ecology of rivers such as the Columbia and Skeena influenced trout size, because the heavy flow of these rough rivers and the very large stones of the river bed meant that smaller steelheads could not breed there successfully. Only the older and much larger steelheads could mate, cut redds and spawn in these torrent-like conditions. Because of their size and the spectacular rivers they inhabit, steelheads are possibly the most exciting trout to catch.