I grew up in Rhode Island and cleaned many a Yellowfin, Bigeye and Bluefin back when they were plentiful. My father fished tunas all summer long. I fished alot off Rhode Island, Nova Scotia and Maine. A former girlfriends father (Japanese girl) showed me how to do it right. The Guidebook for Tuna Fisheries Crewmembers has the same thing with the hose. That is where I got the other language.
Usually I do all but the Tanaguchi (heavy cord down the spine) part.
It is funny that down here in Key West everyone who catches a Blackfin shows it off at the dock like it is the best catch ever. They are fun to catch but compared to YF, Bigeye and BFT they are as bad tasting as Skipjack or Bonito with barely any good meat on them. These guys never even bleed the fish either. These are charter capts who then lug em off to a restaurant or fish house who buys it and resells it after it was treated like a grunt and not even bleed. That I don't understand.
BTW if you have not had Bigeye you will find it is by far the best.