Here's what I found via Google:
The early fishers needed to find a way to cover their fish. They looked to nature for a solution to their problem and soon learned that they could use tree bark. Bark could be taken in strips, flattened and dried to make a cheap cover for their flakes. This popular method of covering fish is even mentioned in the famous Newfoundland song, I'se the By:
'Sods and rinds to cover your flake,
Cake and tea for supper. . .'
The bark, or 'rind' of the balsam fir was used most often because it was thick and could be peeled from the tree with ease. The process of rinding trees was usually done in the spring and began with the removal of the lower branches. A narrow cut would be made into the tree as far as the inner trunk and a special spoon-like tool called a 'rinding shim' would be inserted under the bark. Then the bark was gently peeled away from the standing tree. This was continued until all the bark within reach was harvested.
After being 'rinded' the tree would die. The fishermen called these trees 'white ends' or 'whitings' because the trunk turned white or pale grey as it dried. They later cut these trees for useas garden posts, net bobbers or firewood. In those days, dry white ends for use as splits were a real treat.from Tales of Fogo Island:
http://www.nald.ca/Clr/fogo/page138.htm