Fishing is a blood sport, plain and simple. Responsible C&R makes it a little less so. Still a blood sport, whether you kill them or not. C&R or Kill it and Eat it makes no difference to those who would try to end it.

The fish knows not that we will 'let it go', it only knows the mind numbing terror of being dragged about by unseen forces beyond it's control that are surely leading it to it's demise.
Getting pretty close to anthropomorphizing with that little passage.