The present invention is directed to a pig receiver used in a dewatering method for subsea pipelines. In the dewatering method a pig is placed in one end of the pipeline filled with water and a compressed gas is introduced behind the pig; in addition the water and pig are drawn by a subsea pump operated by a submersible vehicle (SV) operating near the sea floor to a pig receiver of the present invention. A feature of the pig receiver is a gas sensor that shuts the pump off when gas enters the receiver to prevent a gas (vapor) lock of the pump.