Police in the port city of Dalian, northeast China’s Liaoning Province, tightened patrols in the city to crack down on illegal hunting and killing of harbor seals after they uncovered a poaching case involving over 100 wild seals.

Police said on Wednesday that they have strengthened the precision monitoring and encouraged public supervision and reporting to monitor seal poaching.

The poached spotted seals were mostly cubs. Police did not say why they were hunted.

Dalian public found 29 of the wild seals dead when they uncovered the poaching case in February. Despite the rescue efforts, 10 other seals have died.

There are about 2,000 wild indigenous seals living in Liaodong Bay on the city’s coastline.

Police said they have reinforced the police power on the street and in communities to establish a network of daily patrols and promote education campaigns on the mammal’s protection.

The local public security department has required the Changxing Island Economic Zone Administrative Committee to help organize around-the-clock patrols during seals’ breeding and rearing period to combat the illegal activities.