Carl Linnaeus, The Lapland Journey, translated by Peter Graves (Edinburgh: Lockharton Press, 1995), p. 80.
Lycksele Lappmark, 05/06/1732, ¶369:
The parson here had caught powan that were 5 hands in length, which is remarkable. The powan is interesting in that it spawns at Michaelmas at Lycksele church, at Christmas up in the mountains, and step by step at intervals up the river between. Up there the little powan spawns under the ice at Christmas whereas in Småland it spawns at Michaelmas.