Experimental evidence of size-dependent predation mortality in juvenile yellow perch

Adult yellow perch, Perca flavescens, when offered equal numbers of small (52 – 59 mm total length) and large (66 – 73 mm total length) conspecifics, selected more small than large prey in 9 of 11 laboratory feeding trials. The small and large groups were selected from the smallest 40% and largest 15% of a natural length–frequency distribution of young-of-the-year yellow perch captured in the fall of 1985 from Dickie Lake, Ontario. The adult yellow perch predators ranged in size from 23.2 to 26.8 cm total length. Our experiment suggests that smaller individuals of a juvenile yellow perch cohort have a greater risk of mortality owing to size-selective predation than do larger individuals. Factors that affect the growth rate of juvenile yellow perch may therefore influence recruitment by modifying the extent of size-dependent predation mortality.