摘要：The early life history of yellow perch (Perca flavescens) was studied during 1995 and 1996 in two glacial lakes. Pelican Lake contained a yellow perch population with fast growth and desirable size structure, while Pickerel Lake contained a slow-growing yellow perch population dominated by individuals less than 20-cm TL. The first food of perch larvae in Pickerel Lake was copepod nauplii, with a switch to adult copepods by 7-mm total length (TL). However, in 1995, copepod nauplii density was low and larvae began feeding on adult copepods at a smaller length. The 1995 diets of Pelican Lake larvae were similar to those found in Pickerel Lake, where first food was adult copepods. In 1996, Pelican Lake larvae fed on copepod nauplii until 7-mm TL, followed by a switch to adult copepods and increasing numbers of cladocerans. In August juvenile perch in Pickerel Lake were eight times more abundant in 1996 then in 1995, while catches were similar between years at Pelican Lake. Juvenile perch diets in Pickerel Lake primarily consisted of cladocerans and some adult copepods until fish reached approximately 50-mm TL, when macroinvertebrates were increasingly utilized. Pelican Lake yellow perch fed on adult copepods and cladocerans throughout their juvenile stage with only a small proportion of their diet consisting of macroinvertebrates after perch reached 50-mm TL. Because August catches of juveniles were correlated (r = 0.996, P = 0.004) with peak abundance of 10-mm TL and smaller larvae, year-class strength may have been set at an early life stage.
