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A discussion on the Life Cycle of Steelhead Trout

Distribution

WRIA 20

Winter Steelhead in the Quillayute River system are found in all of the major and most of the minor tributaries as well as the mainstem Quillayute. The Dickey, Sol Duc, Calawah, and Bogachiel all have populations which inhabit reaches in fairly high gradient streams, if enough cover is available.

Summer steelhead have a sparser distribution, limited to the Calawah (including the north and south forks), the Bogechiel, the Sol Duc, but are not found in the Dickey. Unlike winter Steelhead, they do not inhabit as many of the smaller tributaries of these four major rivers in the Quillayute system.

WRIA 21

Distribution of winter Steelhead in the Hoh and Queets systems is similar in character that of the Quillayute: They are present in most of the tributaries, major and minor, as well as the mainstem Hoh and Queets rivers

Summer steelhead are generally restricted to the mainstem Hoh, the north and south forks, and Mount Tom creek. In the Queets, they inhabit the mainstem to the upper reaches of that river, the Clearwater, the lower reaches of Matheny creek and the Snahapish river.

WRIA 24

The Bear river and the larger tributaries host winter Steelhead only.

Steelhead Life Cycle Habits

The Steelhead life cycle is impacted considerably by resource partitioning where their life stages bring them into contact with Chinook, and Coho, in particular.

Steelhead spawners look for structures in streams that provide suitable substrate and a refuge from predators. If suitable structure and substrate can be found, they will inhabit virtually any stream from small to large hosting such structures, even within higher gradient streams. The authors of the 2008 WDFW draft Steelhead assessment[1] note that Steelhead are stronger jumpers than either Coho or Chinook and can surmount natural barriers that are not passable to either of the other two species.

After hatching, Steelhead fry move into the shallower portions of riffles and pools to feed. establishing territories rather than schooling like the fry of Coho and Chinook[2].

The juvenile phase for Steelhead lasts a minimum of one summer and one winter, and is in general longer in duration than what is seen for Coho. As the fry mature, they move from the edges of streams, which provide predatory refuge, towards the centers of channels as they grow. Agrawal notes that juveniles have adapted a streamlined body in response to competitive pressure from Coho to move into these areas where flow velocities are higher.

Larger, older juvenile steelhead do not appear to be subject to competitive pressure[2].

The following excerpt describes Oregon's coastal Steelhead affinity for higher gradient streams:

"Juvenile steelhead in Oregon coastal streams are commonly found in gradients up to about 6% (Dambacher 1991; Roper et al. 1994; Burnett 2001) but have been observed to use low-gradient areas in steeper reaches. Roper et al. (1994) determined that densities (number/100m2) of one-year-old steelhead were positively related to reach gradient for gradients between 0.7% and 2.9% and that one of the lowest observed densities was in the single examined reach where gradient exceeded 6%. Steelhead in this same age class were found predominantly in streams with gradients between 2% and 3% (Hicks 1989). Consequently for steelhead, we assigned the highest value to channel gradients between 2% and 3% and assumed no use upstream of reaches with gradients exceeding 15% (Table 1).[4]"

Note that though the authors assumed no use of streams greater than 15% (0.15 rise / run), the workshop consensus and the authors of the 2008 WDFW draft Steelhead assessment maintain that higher gradients that 15% may be used for OWC populations.

[1] Onchorhynchus mykiss: Assessments of Washington State's Steelhead Populations and Programs, J. B. Scott Jr, W. T. Gill, eds; WDFW Feb 1, 2008, 424 pp. (Draft). Also referred to as "2008 WDFW draft Steelhead assessment".

[2] Ibid.

[3] Agrawal et al, 2005

[4] Burnett, et al, 2003