Russ -- Bill just gave the only advice that I could give. When you don't like the parasites (black spot, yellow grub), you have to try to break the cycle. My experience is that high incidence of these parasites seems to occur in "hot spots." Those spots are probably places with more of the fish-eating birds (herons, kingfishers), and seem to just be a natural phenomenon. In the past, we just lived with it. Now, we're trying to play around with the cycle, which is why we stocked pumpkinseeds. I initially didn't really expect much effect, given that we weren't controlling the birds. However, at least in the short term, I have observed far fewer yellow grubs in the yellow perch after we stocked the pumpkinseeds. However, the grubs are certainly not gone.
As for sexing the pumpkinseeds, I just haven't seen much information on that compared with bluegills. Could it have anything to do with the fact that we can produce 10 and 11 inch bluegills, but an 8-inch pumpkinseed is a whopper??
