Jacks of cherry salmon

Like other salmon species, cherry salmon (masu salmon) have jacks. They can be distinguished from fully riverine individuals by their coloration: resident fish have spotted patterns and turn black in spawning dress, whereas jacks lack large spots and their spawning coloration resembles that of sea-run fish.
Given that cherry salmon are already small (on Sakhalin, the typical size is 0.7–1.5 kg / 1.5–3.3 lb), the jacks are only slightly larger than a palm.
All jacks die after spawning, unlike the resident dwarf males.
The last photo shows a comparison of a jack and a resident male in spawning coloration.