Figure 18.1 - 18.3. 18.1. Oncorhynchus gairdneri (Steelhead Trout); scale bar = 1.0 mm. 18.2. Oncorhynchus gairdneri (Steelhead Trout); scale bar = 1.0 mm. 18.3. Oncorhynchus gairdneri (Steelhead Trout); sketch of living specimen; length = 114 cm. (To see enlargement, click on image.)