I've never used periwinkles for the simple fact they are too labor-intensive to gather and peel. If you figure 3-5 per hook it becomes alot of finding and peeling and little fishing. However, if your all alone with summer-runs all over the place and you run out of bait, it is a worthwhile proposition.

Crawdad tails are a great bait in late summer/fall when the fish need to see something different. I've done well with them in the past.

BUT.....If I have to choose 1 bait for summer-runs from the standpoint of sheer effectiveness, hands down it would be GOOD salmon/steelhead eggs. Shrimp would be a distant second.

Just my .02 worth.