For years my favorite lake was loaded with carp in the one pound range. Now most of the carp I see are in the five to seven pound range. My theory is this has to do with hybrid-stripers being introduced to the lake. Could there be another reason?

Hybrids are eating machines. They may well be eating the young carp fry. That would leave more forage available for the older carp to feed up on and grow.

I believe your on to something. Like Curt0407 stated Hybrid Stripers are eating machines. I might add Stripers are eating machines as well. Stripers and hybrids love eating smaller Carp. They will also attack carp cutbait ferociously.

Just like Bluegill, Crappie, Bullhead Catfish, in ponds and lakes, the size of Carp can be a good indicator of predator abundance. Most Carp species can spawn 3-5 times a year. Meaning in the absence of a good predator base they can quickly overpopulate a body of water and become stunted. Smaller Carp are very vulnerable to predation by Largemouth Bass, Hybrids, stripers, Blue Catfish, Alligator Gar, etc...... which decreases Carp abundance, and increases their average size. A large and healthy predator presence almost always translates into fewer Carp, but larger Carp.

This over ambitious Striper died after
choking on a Carp to big to swallow.