Carl Linnaeus, The Lapland Journey, translated by Peter Graves (Edinburgh: Lockharton Press, 1995), p. 71.
Lycksele Lappmark, 01/06/1732, ¶305:
They collect the scales and dry them and the fins, and from this they boil up a watery glue. They dip their nets in this after dyeing them with birch bark and it makes the colour last longer.