WTT Blog - Tagged with electrofishing

I’ve been looking forward to this moment for quite some time now…..well, at least a year. The monitoring of my pet project from pre-intervention (weir notching and removal / partial demolition over six structures) to several years post is quite revealing, and I’ll let the data do the talking.

Now, as a scientist, I know there are a few caveats associated with the figure above. But as there was no specific funding pot for the monitoring of the works for this duration, I am making the best of the situation. So, all surveys were carried out in each of the years for roughly the same amount of time (effort), over similar distances, using similar kit, and roughly the same time of year (although 2018 was a little later because of the incredibly dry spring / summer we have just experienced). Ideally, all of these parameters would have been standardised; ie identical each time.

And so it comes to pass….Coniston Cold weir, which in various forms has been a man-made obstruction to fish passage on the R Aire in N Yorkshire for the past 180 years at least, is no more. Instead, there is now 20.4km of uninterrupted free passage along the Aire and a major tributary.... and all for less than £8k!

Coniston Cold Weir: 19m wide and 1.2m headloss, with a 4m horizontal block-stone apron

I will not reinvent the wheel and spend time here discussing how weirs cause environmental issues. The evidence is abundant and simple to find in the scientific literature, and my colleague Paul Gaskell has recently summarised much of that, here. Then there are global-local events like World Fish Migration Day to raise awareness and I would wager that almost every conservation body involved with river restoration has a hit-list of target weirs on their local patch.