First, that is a nice fish, and kudos to you for releasing it.
No problem with killing one to eat--they are excellent out of the clean, cold waters of Mohave, but as you mentioned, you were not prepared to keep/care for it, and why take a chance of wasting it?
Judging a fish by a photo alone is a guess at best, but there are ways to come reasonably close to a weight based on length (from which you estimate a girth), and just overall comparison to other fish of known weight.
Unfortunately your height is not of help, since your entire body is not in the pic. No mater, as a persons height is usually not used in these guesstimations anyway. Things of know size, such as a 7 inch lure hanging from the fish's mouth are a good place to start, or the diameter of the side plate of a Calcutta 400 would be another.
Neither were in your pic, but a standard of measure is--the width of your sunglasses. Sunglasses come in all shapes and sizes, but one constant for adult type sunglasses is the frame width, since most peoples head's are about the same width.
Anyway, a health fish of that "size" would weight about 13 pounds. Your fish appears to be a little thin, so it would probably be a little less. If I had to guess, I would say 11.75 pounds, and I bet I would be withing 16 ounces.
There are tons of 1 to 3 pound fish on the river, but any fish over 10 pounds is a "good" one.
This Mohave striper was not a "long" fish, but it was a "wide" fish.

The belly on this thing was almost as big as mine
Fish with unusual shapes such as this one are very difficult to guess the weight from a pic alone.
I 6'2", and 230 pounds. Oh that's right, it does not even matter.