Boaties are being asked to report any sightings of a humpback whale which is tangled in fishing line near the bottom of the South Island.
The Department of Conservation said a fishing vessel reported that the whale was near Knife and Steel Harbour between Big River and Waitutu River.
It was believed to have a craypot line wrapped around its pectoral fin and tail, which was trailing for 20 to 30 metres behind it.
Humpback whales migrate north to tropical waters at this time of year, and DoC said the whale could travel up the west or east coast of the South Island.
DoC ranger Mike Morrissey said any boaties who spotted the whale should not get close to it or do anything that would disturb or harass it.
"People seeing the whale can assist our rescue response by staying with the whale, monitoring it and advising of its exact location for our disentanglement team to get to it.
"The whale is moving and is not any immediate danger so urgent action isn't required. The priority is people's safety and ensuring disentanglement is carried out safely by our trained team."
The whale was spotted at Knife and Steel Harbour at the bottom tip of the South Island.
The fishing crew which spotted the whale did not touch it but attached a float to it to make it more visible.
In March, a humpback whale entangled in fishing line was spotted off the Otago coast, and was freed near Kaikoura several days later.
"It helped us considerably in removing the rope from that whale that no one had cut off the rope and float attached to it and we ask that no one does that with this latest entangled whale," says Morrissey.
Whales are freed through a process called kegging, in which grappling hooks are used to attach ropes and floats to the material which has entangled it. This slows the whale down and tires it out, and allows a team to use a series of long poles and knives and cut the material away.
Such an exercise required calm seas and daylight hours, and would take several hours, DoC said.
*Anyone who sees the humpback whale can ring a 24-hour hotline O800 DOCHOT or 0800 362468.