Why is my buddy's lake 300 km north on a completely different schedule?

Because every perch milestone keys off ice-out and water temperature, and both march north by weeks. Spawning at 7–12 °C (45–54 °F) can mean late March on the southern edge of the range, mid-April to May across the Great Lakes and southern Ontario, and into June on cold northern Canadian waters; every later stage — the summer slide, the fall basin feed, first safe ice — shifts with it. Lake size adds its own lag: a big deep lake warms and cools weeks behind a small kettle at the same latitude. Compare temperatures and ice dates, never calendar dates, and both lakes make sense.

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