dgurney

I was wondering if anyone on the forum has any experience of keeping trout in a pond. i have built a pond which is about 18m by 9m and is bout 1 to 1.75m deep. It is fed by springs and has woods surrounding it. Lasy year i put in 6 1.5lb rainbows and 12 3/4lb brownies. I noted thst they were diminishing over the months - only found one dead. My boy did fish a few times with barbless hooks and returned any caught. There now appears to be only 1 large rainbow left (as far as i can see). I have seen a herron by the pond but the water is too deep for it to wade and I've been told thsat all the fish would have been too big for it to take. Is it likely that they have died in summer when the springs were low or maybe a mink? Any advice or insights welcome.