people's reactions when they see you're reading a book about such an obscure subject.

In Newfoundland it is not at all an obscure subject. Since people first started coming here from Europe, the entire economy was based on cod. There's a "famous" postage stamp featuring a drawing of a codfish and the line "Newfoundland currency" or something like that. Even in the New England states it was a huge part of the economy (isn't there a Cape Cod?). (Being in oceanography and all, I can't help but know this stuff...)