Freshwater molluscs flexing their mussels

Pollution and overharvesting are a major threat to our mussels, but Kielder’s hatchery is working to boost numbers on the North Tyne

- Kielder

A number of years ago, courtesy of a good friend, I was enjoying a day on the North Tyne trying my hand for salmon. As I reached the end of a pool, there on an exposed gravel spit was the largest mussel shell I had ever seen.

Thoughts of a salmon were temporarily quite far from my mind as I waded out on to the bar and picked it up. My hands are not the shovel type, but this was big and covered most of one of them when I had retrieved it. I marvelled at the thickness of it, the depth of the wrinkles on the outside of the shell and, last but not least, the sheer brilliance of the interior.

What I did not know then was that, when the creature had been alive, it was probably twice as old as I was at that time. An age of 100 years is not out of the question for a freshwater pearl mussel and that is quite an achievement, especially when we seem to have done our best to destroy them as a species.

My subsequent enquiries told me there are nearly 300 mussel species in the US alone and all but around 80 of them at risk. We have one main freshwater mussel species and it’s in trouble too. All the same old problems associated with our water bodies are to blame.

There are numerous types of pollution: siltation from agriculture and afforestation in the uplands, run-off from ploughing, livestock poaching adjacent to the banks and the release of the residue from sheep dipping tanks.