Faced with falling canned tuna demand, top executives at the big three US tuna companies allegedly colluded to downsize their cans while raising prices, according to filed amended complaints in ongoing antitrust lawsuit cases.

Last week, dozens of plaintiffs, including Walmart and other major US supermarket chains, filed these new complaints against Bumble Bee Foods LLC, StarKist Company, Dongwon Industries Co. Ltd., Del Monte Corporation, Tri-Union Seafoods LLC d/b/a Chicken of the Sea International, Inc. and Thai Union Group PCL.

The collective decision to move to smaller can sizes was made it a surprisingly short period of time.