Forty-seven common carp (Cyprinus carpio) were collected from harbors
in southwestern Lake Michigan in 1993 and 1994, and their stomach cont
ents were examined. Thirty-two of the carp contained zebra mussels; th
e proportion of carp feeding on mussels appeared to be related to the
density of mussels at the site where they were collected. One of the o
nly two carp collected during the lake trout spawning season on lake t
rout spawning habitat contained over 100 lake trout eggs. The fouling
of cobble substrate by zebra mussels probably prevented the eggs from
settling into interstitial spaces, thereby making the eggs vulnerable
to carp predation.