Oil services companies were waiting on Tuesday to see if their legal bid would succeed in overturning a six-month ban on deepwater drilling in the Gulf of Mexico as more fishing areas were closed in response to the worst oil spill in U.S. history.

The ban by President Barack Obama’s administration was imposed in response to the explosion aboard an oil rig in the Gulf of Mexico on April 20 that killed 11 workers and ruptured a well owned by BP Plc, unleashing millions of gallons of crude oil and causing an environmental catastrophe.