I joined the South West Rocks Dive crew for a dive at Fish Rock.

The dive trip began with a friend, Nicky Hammond from the National Parks Association, as we dived to about 24m and photographed some beautiful coral, sea urchins, moray eels, a cuttle fish and a large grey nurse shark.

We were careful to give that shark all the room it needed, as is always the protocol when photographing these magnificent animals.

Although they look really scarey with their overhanging curved teeth designed for grasping fish they are practically harmless, sometimes called “the labradors of the sea”.

Divers had reported the day before seeing a large grey nurse shark with what appeared to be a metal collar around its head and cutting into the shark’s gills.

This had concerned the dive team greatly, as they have seen sharks wasting away when they are inflicted with fishing hooks protruding from their gills or through the effects of swallowing hooks.

The shark was there again on our first dive and Peter Hitchins the dive master was prepared to do something about it.

He had fashioned something like a super-large landing net with a loop attached to the rim to fit over the shark’s head, so the loop of rope could be tightened to secure the shark by the middle.

The loop this time slipped to the tail but it was under control.

The crew drew the shark to the surface with constant pressure and its tail was dragged over the stern.

While some of the crew held the tail securely, Peter began to hacksaw through what turned out to be a plastic rim, like a whitewall on a tyre, which this shark had somehow managed to get over its head.

The plastic had worked its way into the shark’s flesh.

Another dive instructor joined in cutting the collar free and soon they were able to return the shark to swim free with a wonderful Christmas present, the chance to live.

Without that help the shark would have suffered a lingering death from infection.