Packages of mackarel are “the coin of the realm” in federal prisons, says the Wall Street Journal. There has been a prison mackerel economy since 2004, when smoking was prohibited, so inmates couldn’t barter cigarettes. Prisoners need a proxy for the dollar because they’re not allowed to have cash. Money from prison jobs (which pay a maximum of 40 cents an hour) or family members goes into commissary accounts that let them buy things such as food and toiletries. Mackerel supplier Global Source Marketing Inc. says demand from prisons has grown since 2004. Demand has switched from cans — which wardens don’t like because inmates can turn them into knives — to plastic-and-foil pouches of mackerel fillets.
Global Source sold more than $1 million of mackerel for federal prison commissaries last year. It accounted for about half its commissary sales, outstripping canned tuna, crab, chicken, and oysters. Unlike those more expensive delicacies, the mack is a good stand-in for the greenback because each can (or pouch) costs about $1 and few — other than weight-lifters craving protein — want to eat it. Inmates stash macks in lockers and use them to buy goods, including illicit ones such as stolen food and home-brewed “prison hooch,” as well as services, such as shoeshines and cell cleaning. The U.S. Bureau of Prisons says that inmates caught bartering can end up in the “Special Housing Unit” — an isolation area also known as the “hole” — and could lose credit they get for good behavior.