Yes they were most likely leeches.

Here in the Pacific Northwest there are a number of species of leeches found (a dozen or more). They are found in both moving and still waters. They can vary in size from less than an inch to several inches long and in color from a pale whitish to almost black. While all the species have "sucker mouths" none of those found in this region are blood suckers. They use their sucker disks to hold on the bottom and other objects. If you are wading in an area that has leeches (typically slow water with fine sediments and detritus you may find some attached to you -just pull gentlely to remove. Even though there may be a red mark where they were attached to you they really are just attaching themselves to you as any other object - not trying to feed on your blood.

In the rivers ther various leehes tend to be most active during warmer temperatures and in slow moving streams thus one is more likely to see them on salmon than steelhead. Have seen leeches on all salmon species and really on steelhead (usually a late spring winter or late fall fish). the steelhead are much less prone to hold in slow water areas than salmon. Most commonly see leeches on coho but have seen years when it seems ever chum is load with them.

In one case (in 2000) the fall flows were very low and the chums quite abundant. In one small creek on the Stillaguamish there was some significant pre-spawn mortality on the early chums (afer a significant rain and rise in the creek the problem disappeared) The fish's gills were absolutely load with leeches it was thought that the heavy infestation contributed to the pre-spawn mortality; along with stress from having huge numbers of fish (several 1,000 in little more than 1/2 mile of stream) in flows that were lower abd warmer than normal.

They are just another example of the great bio-diversity found in our rivers and should not be great concern.

Tight lines
Smalma