Biologist on efforts to free sperm whale

Divers and biologists fought for hours over the weekend to free a sperm whale trapped in an illegal fishing net almost 14 miles (22 kilometres) off the Italian island of Salina, north of Sicily.

Sicilian biologist Carmelo Isgró said the Coast Guard managed to free most of the sperm whale between Saturday and Sunday.

However, as soon as the young mammal was able to move more freely, divers could not complete the operation because the whale was too agitated.

It started to swim away and began diving deep into the sea, Isgró recalled from his hometown of Milazzo in Sicily.

Underwater images captured by Isgró showed straight lines on the head of the sperm whale, what the biologist described as 'deep and very painful wounds' caused by the net as the animal tried to liberate itself.

Such nets are commonly known as 'walls of death.'

They are usually placed about three nautical miles off the shore, reaching as far as 40 metres below water and are several kilometres long.

They often end up trapping endangered species like turtles or sperm whales.

Isgró manages a local museum that hosts the skeleton of another sperm whale that died three years ago after being trapped in an illegal fishing net.