London ? A school of mechanical, battery-powered robots in the shape of fish will be released into a Spanish port to help monitor pollution there, scientists said Friday.

The 5-foot-long robots work by mimicking the swishing movements of a fish’s tail, according to University of Essex robotics expert Huosheng Hu, whose team is manufacturing the machines.

He said the robo-fish would be equipped with sensors to monitor oxygen levels in the water, detect oil slicks spilled from ships or contaminants pumped into the water from underground pipes.

The robotic fish will patrol the harbor of Gijon, in northern Spain, under a $3.6 million grant from the European Union. Hu said that Gijon was chosen because the port authorities there had expressed an interest in the technology.

Information gathered from the robo-fish would be transmitted to the port’s control center using a wireless Internet signal when the devices surfaced.

The data gathered would be used to create a three-dimensional pollution map of the harbor’s area.