These stockings seem to me like taking a sticking plaster to a gunshot wound.
The problems the rivers have in the first place is that the environment does not self-populate with fish. Because of lots of different factors - though my personal opinion on this is that the problem is the availability of both suitable breeding grounds and a healthy population of breeding fish. Thus, over a number of years when the spawning fails, what actually happens is that the remaining population of fish starts to get bigger (because the overall biomass of available food is being consumed by a smaller and smaller number of increasingly sized fish). And during this period, you never hear anglers saying... "where are all the 2lb chub and barbell? Something's very wrong with the ecology of my river!! EA, investigate this please!!" No, instead what happens is those fisheries are celebrated, probably moving away from clubs and turned into syndicates and such like. A barbel's lifespan - according to 0.7s of searching on google - is 15 - 20 years. So the fishery could be in immense decline for a good number of those years, but everyone's catching doubles so no one bats an eyebrow.
But then those fish die out. Either from old age, or predation. Let's face it, a fat old 16 pound barbel must be an pretty easy target for anything with claws and fur. But the problem isn't the predator. The problem is that the 16 pound fish that has just had its liver and gills torn out hasn't (successfully) had his end away for a good number of years! No kids, no grand kids, no great grand kids, nothing. Just a big rotting hulk left out for the nearest fox or red kite to haul off.... (who's kids, incidentally are thriving!)
It drives me mental that the very agency within the government that should be most concerned with this are so inept at looking at the real root causes. They're the Environment agency after all, surely they should be doing more to protect and enhance the environment. Stocking fish - the only time I see that making any sense is where a pollution incident really wipes out a properly healthy river, i.e. one where the fish are breeding successfully. And for anyone who's not sure what a really healthy river looks like, spend a day on the banks of the wye in the summer when the waters clear and chuck any kind of bait into the margins and see what happens. Fry will appear from nowhere and annihilate it. Because the fish are breeding (no end of access to good clean gravel) and thriving.
(And guess what, the barbel never get much more than 13 pounds! Who wants to catch a tiddler like that!)
These issues of environment just never seem to get addressed by the EA. Dredging, yes. Pulling out bankside cover, yes. Blind eye to abstraction (reduces flow and oxygen levels over spawning gravels) - yes. I'm sure this list could go on. But rarely do I hear anything about really improving the chances of natural stock recruitment, which from their responsibility towards angling should be a number one priority. Stocking fish - if anything - is just a colossal admission of their own failings in being guardians of our environment.
(Steps off soap box, wishes the blooming weather would warm up a bit so the fishing would improve.....)