Fishers, I think a walrus is equipped with that sort of rigid reinforcement too, called an oosik by the Eskimo. You can buy them carved and polished as a souvenir.
On my boat, I have a ruler that someone gave me for measuring fish. On one side the units of length are compressed, something like 15 inches in a foot long ruler, you use that side to measure YOUR fish. On the other side the units are elongated, maybe 9 inches in the ruler, and you use that to measure your buddy's fish.