摘要：The ontogenetic diet shift to piscivory can be energetically beneficial
for fish growth and allows larger, more energetically profitable
prey to be consumed. A shift to piscivory may be easier for
longer individuals within a cohort due to larger gape size, and an
early shift is likely advantageous, potentially leading to increased
growth rates and survival. Such length-dependent ontogenetic
diet shifts may explain the intracohort variability in length that is
common for age-0 walleye (Sander vitreus). The objectives of this
study were to describe seasonal intracohort variability in length,
identify the timing of the shift to piscivory and determine if the
onset of piscivory was length-dependent in age-0 walleye.
Walleye initially fed on zooplankton, but shifted to piscivory during
July of 2010 and June of 2011. The onset of piscivory in age-0
walleye was associated with length-dependent differences during
both years, in which longer individuals within the cohort became
piscivorous earlier than shorter individuals within the same
cohort. Intracohort variability in length was detected and
increased postontogenetic diet shift. Age-0 walleye that experience
a growth advantage could benefit from increased survival
and feeding opportunities.
