It says,,,,Then I drag the barrel across the deck to the fishbox and put the fish in (saves blood drips). I typical dory fashion, the box is huge (70" long, 15" deep, 17" wide)s, and spans the full width of the boat under the console. It drains overboard on both ends. For tuna fishing I plug the drains and fill it most of the way with ice. When I start putting tuna in the box I pour in a few gallons of saltwater to make slush. As I keep adding tuna, I add water as required, but at that point the ice is melting and making its own water.
Hence the tuna stay in icewater **slush** the whole day. I can put about 20 tuna in there. When we get to port, the water in there is so cold it hurts to put your hand in it and the tuna are nicely chilled.
Voir a....
https://www.ifish.net/board/showthread.php?t=417967