Retriever systems for marine geophysical survey cables. At least some of the illustrative embodiments are methods including causing a submerged sensor streamer to surface. The causing may be by moving a piston within a cylinder of a housing coupled to the sensor streamer, the moving of the piston responsive to pressure exerted on a face of the piston as the sensor streamer reaches or exceeds a predetermined depth, wherein the pressure exerted on the face of the piston overcomes a latching force tending to hold the piston in place at depths above the predetermined depth; and responsive to the piston overcoming the force that latches the piston releasing a ballast weight, wherein prior to the releasing the ballast weight is at least partially held in place based on position of the piston, and the releasing responsive to movement of the piston.