Thanks for sharing Graham,
Not an easy problem to fix as it doesn't appear to be consistent across the countries. I do believe pollution and drainage are a major factor, and as yet we still don't know what impact commercial fishing has on sandeels and salmon themselves out at sea with our super sized fishing vessels nowadays. I also think if you look at South of England for example where many of the steams have gone completely due to water abstraction from water companies these are all contributing and exacerbating the issues.
Good to see that their plight has been recognised and hopefully with a combined effort across the North Sea and North America we can invest more in understanding some of the challenges. Certainly rivers which are focusing on razor bill, seal and mink predation and smolt herding seem to be fairing better than those who don't have the resources to. But that is not a scientific evaluation.
It is an emotive subject and one I am sure will get plenty of posts and discussion.