what is the going price for yellowfin in LA, if there is a worthy market?..
Depends on the grade(color of the meat) of the fish and where the market is at the time.
#1 (bright translucent cherry red)= $5-$7/lb
#2 (little pinker than #1 and a little more opaque)= $3-$5/lb
#3 (light pink to white to even some brown)= $.50-$1.00/lb
Most rod n reel caught fish will be in between a #2 and a #3 which depends on how you take care of it. I've seen a bunch of recreational/charter fisherman try to sell tuna when we were in the business and get upset they couldn't get top dollar for their tuna. It really depends on the grade and the meat color.
Commercial boats catch tuna on longlines which tax the fish way less than a rod n reel then immediately when it hits the deck(while still alive and kicking), the head is cut off and it's gutted. Next it goes into a chill tank (with ice water and salt to make it even colder) to drop the internal temperature down as quickly as possible. After chilled sufficiently it's put down below in the ice hole and plenty of ice is stuffed inside(the cavity of the fish) and outside of the fish.