I don't understand why the skipper sanctioned the killing of this fish. I once fished off a boat in the Canaries where they routinely kill the catch, I was not aware of the policy and when I complained the skipper informed me quite forcibly that that was classed as the deckies bonus.
I don't bother going out on those boats any more.
I've also seen Tope landed in Mediterranean ports and only the fins taken, these are the same fish I fish for in Cardigan bay every summer. I'm sure they're more valuable as a sport fish than they are for a one off payment for the dorsal fin.
I was not aware that the meat spoils after a long fight, is that because of the lactic acid build up?