A rare southern right whale triggered an emergency response when it became entangled in a cray pot rope off Portland last week in at least the fourth entanglement operation off south-west Victorian waters since 2018.

There have been 28 reports of whale entanglements since 2003 in Victoria with an above average number of 11 in the past five years.

A specialist team searched for the whale from air and on land but has now scaled back the operation after failing to find the mammal, which last appeared near Narrawong. Experts say it will eventually die unless freed from the rope.

Animal Justice Party MP Andy Meddick said more priority should be given to whales, suggesting that adhering to a code of practice for fishers should be mandatory.

"When we are talking about a critically endangered species they should be the first consideration," Mr Meddick said.

Rock lobster fishers currently follow a code of practice that cautions them against using excess line, leaving pots in the water for extended periods, and requires anglers to report entanglements.

But Seafood Industry Victoria rock lobster director Matthew Harry said no level of caution from fishers could completely rule out entanglements.

"It's about reducing it to a bare minimum," Mr Harry said. "It's a bit like the road toll in that there will be risks."

He said the code of practice was currently under review, and technology upgrades such as using weighted lines, not setting pots in clusters and education campaigns were the only strategies available to reduce risk.

"The last thing any fisherman wants to do is catch a whale, it is just the worst thing you can do," Mr Harry said.

He acknowledged that some might see the code of practice as lacking enforcement but he believed it encouraged industry to co-operate on solutions and report incidents.

"Some areas of the coastline might be more prominent, and a one size fits all approach doesn't work. If we can get industry to discuss that and come up with workable solutions you're going to get better outcomes," Mr Harry said.

The Department of Environment, Land, Water and Planning's Mandy Watson said photos of the junior whale entangled last week matched images of a rare grey whale born off South Australia last year.

The mammals usually appear black and researchers have only recorded 20 of the "grey-morph" whales off the south-east Australian coast.

"It's one of the things that make them harder to see from the air and the water, they blend in," Ms Watson said.

She said the entanglement would likely become infected and cause the whale to die, but that could take about a month.

"We have assessed it as a lethal entanglement," Ms Watson said. "That's why so much is invested in trying to remove the entanglement; it's an endangered species and it's a high priority to protect it."

She said the only hope now was that it appeared somewhere else along the coastline with South Australian and Tasmanian authorities aware and also trained to disentangle it.

DELWP has specialised trained and accredited response teams, which train annually, along the coast to respond to the entanglements.

If members of the public sight the entangled whale they can report it on 1300 136 017.

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