Reduction of the pelvic skeleton in the threespine stickleback, gasterosteus aculeatus, in two lakes of québec

Populations of Gosierosieus aculeatus having reduced pelvic skeletons are reported forthe first time in Eastern Canada from the Saint John River drainage in Québec. Examination of 120 specimens from 12 collections revealed pelvic skeletal variation from total absence to a full complement of incompletely developed pelvic elements. Bilateral asymmetry in pelvic structure was common. Brook Trout. Salvelinns fontinalis, were recorded from both lakes and were known to eat G. oculeotus.