Authorities are trying to determine what caused the death of a harbor porpoise that washed up on a southern New Jersey beach this weekend.

Harbor Porpoise (Wikimedia Commons)

Robert Schoelkopf, director of the Marine Mammal Stranding Center, tells The Press of Atlantic City that the porpoise found Saturday in Margate likely died after becoming tangled in fishing net. But he said a necropsy will be performed to determine the cause of death.

Schoelkopf also noted that numerous grey seals were spotted on Jersey Shore beaches over the weekend.

He says none of the seals that arrived in Atlantic City, Avalon, Long Beach Island and Ventnor were in distress. But they did attract large crowds of onlookers, which meant the stranding center had a busy day relocating the seals to uninhabited areas.