Porpoise or orca wouldn't stay down that long over some of the extended fights referenced.

Fought a halibut for 2+ hours in admiralty inlet when I was a kid - finally got it close enough to see it was a halibut as big as our 16' boat (width) and cut it off. But that was on heavy salmon trolling gear.
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. . . and God said unto them, Be fruitful, and multiply, and have dominion over the fish of the sea . . .