Peruvian authorities were investigating Sunday the deaths of some 500 sea lions whose rotting corpses were found on a northern beach.

Environmental police told the official Andina news agency that the decomposing bodies of adult and juvenile sea lions were found on a beach in Santa province about 400 kilometers (250 miles) north of Lima.

Police are investigating a complaint from the governor of the local Samanco district, who said the sea mammals had been poisoned by marine farmers and fishermen who harvest shellfish.

Sea lions come close to the shore to look for seafood and scallops to eat.

City workers hauled away the corpses, which risked posing a public health hazard.

In early November, the bodies of another 187 sea lions were found in the Piura region farther to the north of Peru, along with four dead dolphins and the corpses of sea turtles and dozens of pelicans.

Wildlife officials are investigating those deaths but have yet to announce their findings.

A range of possible causes are being considered, including disease, entanglement in fishing nets, the ingestion of plastic trash and hunting.