A great & tough question to answer, EP. It's obvious that the gastric juices in that Chinook tummy quickly dissolve most of the normal key ID meristics used to speciate small forage fishes - like the presence of an adipose fin, scales, etc. Only salmon & smelts have an adipose - herring & anchovies do not. Herring also have a lower jaw that protrudes; and large scales that easily slough off (that you can see if it is not too digested), and a strongly forked caudal tail. Smelts, on the other hand not only have an adipose but also have a small mouth, maxilla not reaching mideye;Are those Chovies? Or juvenile Salmon?
and a short pectoral fin:

