If LMB are your main fish of concern, don't touch those shiners. If you're more focused on BG, you could remove some of the larger GSH. Personally, I wouldn't worry about removing any either way. As long as you have a decent population of bass, they will bring the GSH into control on their own if given a little time. It only takes about a 10 inch LMB to eat those bigger shiners you've seen.