How to control perch infestations is covered well in the following document:
Using Rotenone To Renovate Fish Populations
In Farm Ponds
Found it here:
http://msucares.com/pubs/publications/p1954.htm
To remove the perch from Cow Lake may cost upwards of $1.5 million - that's a lot of money to return a lake to where it could raise 18 lb. trout. But who care about 18 lb. trout - there are people that really like 4" perch.
Don