NBC day at Lost Creek

[BearLakeFishGuy]

The deformed tail is a hatchery artifact.  As the fish are growing, they begin nipping each other.  This slows down as the fish get larger, but once the injury is there, the fin rays (cartilage) will typically grow out deformed and this is what you see.  Sometimes its just a genetic deformity, but those fish typically die prior to stocking.  You will not only see this on the tails but on the dorsal fin.  The fish missing their pectoral fins have typically wore those off on the raceway walls (concrete is abrasive), but most of the hatcheries have mitigated this to a large degree now.  Those "finless Freddies" were pretty typical up to around 2000 but since that time they are less frequent.  Hope that helps!