I'll throw in my two cents worth...

Pics 1 and 2 are unquestionably male, northern BG.

Number 3 appears to be a gravid female HBG.

Number 4 looks like a male HBG to me. The breast color is darker orange, and the "hump" on the breast is more defined. My female HBG have a much more streamlined transition from lower jaw to stomach. Just like pic #3.

One more thing.. Hybrids typically outgrow BG for the first couple years. Judging from their shape, long and slender, they appear hungry. They should be almost as "tall" as they are long. Are you providing supplemental feed? The native fish appear thin also, and not just because they're spawning.

"Forget pounds and ounces, I'm figuring displacement!"

If we accept that: MBG(+)FGSF(=)HBG(F1)
And we surmise that: BG(>)HBG(F1) while GSF(<)HBG(F1)
Would it hold true that: HBG(F1)(+)AM500(x)q.d.(=)1.5lbGRWT?
PB answer: It depends.