Why do perch lakes run in boom-and-bust year classes?
Because zero parental care hands the whole outcome to spring weather. With no guarding, survival rides on what happens to eggs and fry in their first weeks: a warm, stable spring floods the lake with one enormous cohort; a cold, windy spawn — ribbons stranded, plankton bloom mistimed for the fry — can nearly erase a year class. The lake then spends years showing you that history: "all 15 cm (6 in) fish" one season, jumbos everywhere five years later, is a single strong cohort marching through the population. It also means a slow year on your lake is usually demography, not disappearing fish — and that the boom cohort, competing with itself, may grow slowly until predators and anglers thin it.
The full story
This answer is one piece of a longer lesson — setups, diagrams and the reasoning behind it.
More questions about Spawning
Same topic, other species
- Why is crappie fishing great one year and dead two years later? — Crappie
- Do male or female largemouth guard the nest? — Largemouth Bass
- Why are so many muskie fisheries stocked? — Muskellunge (Muskie)
- Why do some lakes fill up with stunted "hammer handle" pike? — Northern Pike
- How deep do smallmouth spawn in ultra-clear water? — Smallmouth Bass
- Do stocked hatchery trout spawn successfully in the wild? — Trout (Rainbow · Brook · Lake)
- Why are walleye seasons closed in spring across most of Canada? — Walleye