if you are in the frsh water i like bunny leeches. A purple egg sucking leech is always a good bet. Pink is a good color for cohos and while i have never fished the Skok for silvers i have caught a lot of them on other rivers using a variety of pink or purple flies. Sometimes on a clear river like the Sol Duc i like to use a small webby pink spey fly(size 4) while on other rivers i sometimes like to throw a big pink leech with a weighted head.
good luck.