Bishop hurt his hamstring and sprained his knee in the first quarter of the Packers' preseason loss at San Diego on Thursday and had to be helped to the sideline.
McCarthy said Saturday night, "Unfortunately, the hamstring injury is what we feared."
Bishop, a sixth-year player out of Cal, started 13 games for the Packers last season -- missing three with a calf injury -- and had five sacks. D.J. Smith would likely take his place.
McCarthy said cornerback Devon House will miss two to three weeks with a shoulder injury and running back James Starks is "week to week" with a turf toe injury.