Couple points... Salmonids are the primary fish with adipose fins (catfish is another group) as far as sport goes... and hatcheries clip the adipose to indicate the fish is a hatchery fish... which may be killed in many places, where wild fish may not be.
Clipping the adipose would make the fish a "legal" take in lots of places. That may be part of what CA is worried about.
It has long been held the adipose does nothing and clipping it has no effect on fish. Fairly recent studies have shown adipose-clipped fish actually keep their tails moving in power strokes more than 10% more than non-clipped... The hypothesis is that the fin acts a vane to increase efficiency, or so I read a while back.
Mark Begich, Joaquin Jackson, and Heller resistance... Three huge reasons to worry about the NRA.