"One of the things about commercial fishing is that everything seems to be extreme. Fishermen don't work in any normal sense of the word, they're at sea for a month and then home celebrating for a week straight. They don't earn the same kind of money most other people do, they come home either busted or with a quarter-million dollars' worth of fish in their hold. And when they buy food for the month, it's not something any normal person would recognize as shopping; it's a retail catastrophe of Biblical proportions.
"Murph and Sully... begin stalking up and down the aisles throwing food into their carts by the armful. They grab fifty loaves of bread, enough to fill two carts. They take a hundred pounds of potatoes, thirty pounds of onions, twenty-five gallons of milk, eighty-dollar racks of steak. Every time they fill a cart they push it to the back of the store and get another one. The herd of carts starts to grow—ten, fifteen, twenty carts—and people stare nervously and get out of the way. Murph and Sully grab anything they want and lots of it: ice cream sandwiches, Hostess cupcakes, bacon and eggs, creamy peanut butter, porterhouse steaks, chocolate-coated cereal, spaghetti, lasagna, frozen pizza. They get top-of-the-line food and the only thing they don't get is fish. Finally they get thirty cartons of cigarettes—enough to fill a whole cart—and round their carts up like so many stainless steel cattle. The store opens two cash registers especially for them, and it takes half an hour to ring them through.... Bag by bag, they carry $4,000 worth of groceries down into the fish hold of the Andrea Gail."
—Sebastian Junger, The Perfect Storm, 1997 (NY: HarperCollins, 1999), 32–33
Not as quick, though. I imagine they do go to Costco- or Sam's Club-type stores when they can; this was in the early 1990s though.
I like the scenes on "Deadliest Catch" when they show the guys grocery shopping for their trips. (They don't really show them every season anymore, but they did for the first couple.) They still do spend several thousand bucks for a few weeks' worth of food for just 4-6 guys. But they work their asses off and need probably 4000-5000 calories a day.