I would be using a rod in each hand and putting a jig in their face instead of spider rigging with many presentations. If they mark at 15 then start at ten and work your way down a foot at a time until they hit. Slow presentation with almost no movement of the jig. The cold water slows them to where they wont chase much of anything very far or very fast. Focus on figuring out the fish and presentation and then multiply it. I would use something close to a baitfish in color with MAYBE a tip of chartreuse. If you get a bite figured out you may not want to use more than one rod, it's a ton of fun.