Humpback whale
A humpback whale, which beached in New Jersey, died. Russell Boyce/Reuters

A humpback whale has been washed up on a beach in New Jersey.

The 33ft long mammal – weighing 20 tonnes ­– was found near 20th street in Sea Isle City on Friday.

The cause of its death is unknown but was currently being investigated by officials from the Marine Mammal Stranding Centre.

Bob Schoelkopf, the centre's founder, said there were with no visible signs of injury or trauma, but it appeared to be emancipated.

Humpback whales primarily eat small fish and krill. However, during breeding seasons they fast and live off fat reserves.

Schoelkopf said this was the second whale to beach themselves along the Jersey coast this year.

Tourist Ann Heffer told the Philadelphia Daily News: "It's sad to see such a beautiful animal dead on the beach like this. I'm glad this doesn't happen every day."

Humpback whales were first protected as endangered animals in 1966.

Currently, it is believed 30,000-40,000 humpback whales are left, which is around 30% of their original population.