I'm with Steelhead, around 200# though that would be at the most. My initial thought upon seeing it was more in the 160-180 range at the time of the photo. It does not appear to be a young bear though it is not an old boar. My guess it is a mature female without cubs as that would satisfy the majority of the visual cues. Such bears tend to run in the 180-220# range through their fertile years which would meet the mature looks and smaller size criteria. Going out on a small limb, I would place its age from 5-10 years of age based on a lot of time sitting over baits and a few years working a big game check station where I got to see a couple dozen dead bears a year.
As mentioned, the physical dimensions of the bear would help. There are some decent reference points in the picture but the angle of the bear and not knowing the actual dimensions of the tree nor distance from the tree of the trail makes for a lot of guessing.
