I have travelled throughout Africa and looked at malaria activities and based on my experience using malaria nets for fishing is purely anecdotal. It is obviously not a good thing, but it is not a pervasive thing.

Of interest, people also use malaria nets for gardening. They are used as a means to keeps bugs out of crops.

The more complicated issue is whether people are using the nets properly. It takes discipline to correctly put the net over your body the entire night and sleep under it.