Sorry about being unclear. Here are some things to clarify what I was trying to say.

I was using the term "selective" in the genetic or biological sense. ie using selective from the fishes perspective. To harvest a given type of fish is to select against its reproduction.

My gripes with gillnets is they genetciallyselect for the reproduction of smaller fish (ie only small fish escape the nets).

My gripe with trollers is that they catch (genetically select agaist) aggressive fish.

As an angler this makes me unhappy becasue these types of fishing result in a trend towards smaller less agressive fish.

If I understand these traditional set gear methods all the fish are placed in a waterfilled box or pen where they can survive for hours if not days. One could then look at each fish to determine if it is desirable to harvest or release that fish. Thus wild fish or different species from the one targeted could be released unharmed.