These fish are fairly enigmatic in most of the Finger Lakes. They are abundant in Skaneateles Lake. Numbers in Cayuga and Owasco Lake have gone up over the past couple years. Canandaigua Lake has a decent population of good sized fish. Seneca Lake is also fishing fairly well for rainbows.
They seem to tolerate or prefer warmer temperatures than the other salmonids, so they are occasionally taken while bass fishing. We encounter a few while lake trout jigging or casting for salmon/browns, but I consider them a bonus fish, apart from Skaneateles Lake. For sheer numbers, Skaneateles is THE lake for these hard fighting fish.
Rainbows on Skaneateles Lake eat plenty of crayfish and insects. This helps keep the fishery predictable. Find the areas with abundant food, and you’ll usually find the rainbows. I do well on them once water temperatures drop into the 40s and below. They can be taken fairly regularly throughout the winter and I do well into the spring through at least May. In mid June mayfly hatches on Skaneateles Lake can provide decent fishing. They fight great and are strong fish!
Here's Mark I. with a nice fish out of Skaneateles Lake.