I have read quite a number of posts re: pearl mussel and problems with authorities and stream enhancement, Do those that make the decisions realize that part of the life cycle of the mussel is symbiotic with young salmonid species, I can understand the frustration around the country where anglers do their best to improve enviroments only to be frustrated by the man behind the desk,It seems yet again our authorities here are using the old rule (left hand shall not know of right hand)

In the interests of balance - the presence of the pearl mussel has been used successfully in WTT collaborative projects as a reason to carry out habitat works that benefits local wild trout.

This was for the very reason that you point out - the mussel larvae need a salmonid host to complete their lifecycle.

So sometimes it also works out as a positive situation .