Rich G
Those fish are most likely resident rainbows. We see a few in all the North Puget Sound streams. The 14 to 20 inch fish are sexually mature and are 4 to 7 years old. Have seen fish that were as much as 10 years old (having spawned 5 or 6 times) and were the size of small steelhead. Tend to see more in areas that are lightly fished or that have restrictive regulations. For example with the catch and release regulations for all but hatchery steelhead on the North Fork Stillaguamish the rainbows are becoming more common. The spotting tends to vary form river to river as well as with the condition of the fish.

It is my belief that they are part of a steelhead/rainbow population complex. Where the rainbows are fairly common (for example the Cedar River) it is not unusual to see the rainbows spawning with steelhead; there appears to be genetic exchange between these two life history forms of O. mykiss.

Historically they were likely fairly common and may have provided a "safety net" for the species complex; escpecially in times of poor marine survival. While it is commonly believed that Western Washington streams are nutrient poor and can't support large resident fish historically the opposite was the case. There reason of course was the presence of abundant salmon whose carcasses, eggs and fry all supply the needed food base to support good growth.

In order to see more of these fish we need two things: functioning river systems and enlighted fisheries management. A healthy river system would supply the need habitats for both the trout and salmon. The fishing regulations needed include: large minimum size limits (or catch and release) and bait bans (especially during the summer). 30 to 35% hooking mortality per capture over 4 or 5 years severely limits the survival of these fish. The final piece in the management puzzle is achieving good escapements of salmon.

When you encounter one of these resident fish wish them well as they signal that there may be hope for their home - our fishing holes.