Re: Getting Rid of Didymo
No doubt that the occurrence of didymo over and above whirling disease is probably the most serious issue we have to deal with.
I have very closely followed all reports and known data related to this.
I first became aware of its presence here on the White about 6 years ago. Prior to that it was not present.
There is no doubt that at the Bull shoals dam zone it has in the last 3 years been responsible for the decline of the trophy trout, particularly the large Bows we used to have here. they are all but gone.
The reason being, didymo forms a carpet over the substrate that more or less eliminates the trout from the primary invertebrate food sources, which were, sowbugs, scuds and chironomids.
It reduced further the habitat for sculpins and crawdads, both of which prey on the above species.
All of which are food base for trout.
We do not see here the aggressive growth that many of the rivers in NZ are subject too, and this is almost certainly due to the fact BSD is a tailwater, and there is no constant so far as water levels and flow rates, which is the case for the majority of the NZ systems.
What can be done. Very little. There is at this time no known way to deal with it. There certainly has been research to find a answer. Dealing with vegetation growth in lakes and ponds is practical, all be it there my be some adverse effects from the chemicals used, largely copper sulphate based.
Tests have shown that didmo in a small confined zone can be killed, but it does not eliminate it 100%
How do you introduce the volume of chemical needed into a moving water system of many miles and then maintain the required percentage of chemical base needed through the miles of that system.
Even if you have some effect, it is very unlikely you will eliminate the spores totally.
And by doing so to what extent do you also destroy further invertebrate food base, it is indeed a problem either way you look at it.
Is it possible to reduce further contamination from a contaminated system to another, l doubt that, as not all anglers are so minded to deal with decontamination of waders and boots, nets, boats, trailers, fly lines, even the flies we fish with.
Then we also have many species of birds that move from one system to another.
There are some rivers in NZ that have been closed, and many that have very strict regulations for access.
Is it likely we will see that here in the US, l doubt that.
Aaron, a correction here by the way, it was rivers that were more so shaded that reduced the incidence of didymo growth.
Davy.
Re: Getting Rid of Didymo
Id like to add something in here ,When I was young the upper muskinetgon( sorry for thr spelling )Use to have very little vegitation as far as underwater weeds ,it is now clogged .In the summer it is infested ,I relate this to people all the way up to lake hopatcong,who dump grass into the lake and river ,and also fertilize like crazy around watersheds . I belive it is us who are helping these plants grow ,by introducing phosperous to the water system .Didymo may be a spore but it needs stuff to survive .As humans we are impacting our watersheds everywhere !!!!!!!Even help introduce foriegn fish species ,we are the alien here on this plant ,and we are destroying it ! Education is the key and laws to enforce no dumping of grass and no fertilizing in watershed areas is the only way to stop these invaders ! peace out ya all
