After a minute of controlled breathing, inhale deeply, and then duck below the surface. You’re scouring for rounded shells attached to rocks or to the thick bodies of floating kelp. You’re carrying a foot-long abalone iron and you’re prepared to move fast.

Despite abiding by strict regulations that require free-diving and a catch limit of three a day and 12 a year, the diehard abalone fishermen of northern California received a blow earlier this month.