You are quite correct about the 'holt', but it is the worst example of a 'holt' you'll ever encounter, basically a plastic box with 4 foot of plastic pipe leading into it and I would say that it's never had an otter in it! Lots of trout and chub on the river there but there's also billions of minnows. And there's always a hell of a lot of otter trade, should someone know what signs to look for. I actually have photos of the fish passes being made, as well as other areas on the Aire.... They were made late last spring/early summer.
Yes the minnows are a pain! Iv live baited them a few times