Nah, they all go back. Need to conserve fish stocks for future generations. That 13lb fish probably entered the river in early summer so it hasn't eaten a good three or four months. They enter the river in peak condition looking like a bar of silver. They're only worth keeping to eat when they're fresh.
Went out yesterday (24th) to sort out taking some good photos of the partial eclipse of the sun then (after about 40 minutes) realised the eclipse was today Went out this morning and took these (you need to zoom in on some to see it)