A young whale trapped in fishing nets in Sydney Harbour has been freed after two days of desperate efforts by rescuers.

There was jubilation among rescuers when the juvenile humpback was freed from its entanglements on Friday morning.

The rescue was led by National Parks and Wildlife officers and also involved people from rescue organisation ORRCA and NSW Maritime, as well as a member of the Gamay Ranger Indigenous knowledge group.

“A juvenile humpback whale entangled in netting has been set free by the NPWS disentanglement team, with support from ORRCA, after spending about 20 hours in distress within Sydney Harbour,” ORRCA posted on Facebook shortly before midday on Friday.

It came after the struggling whale was first noticed by people on shore about 1pm on Thursday and reported to ORRCA’s hotline.

Rescuers spent hours on Thursday trying to dislodge the fishing tackle that had trapped the young mammal before growing darkness forced an overnight halt.

Wildlife officers placed large orange buoys or kegs on the humpback, which was about half a kilometre off Bradley’s Head, to slow it down and allow rescuers to keep track, before rescue efforts could resume early on Friday.

An exclusion zone was imposed as crews chased the distressed whale through the harbour, trying to get a chance to disentangle it from what was believed to be lobster pots.

On Friday morning, Macquarie University whale expert Jessica Fox told The Sydney Morning Herald that rescuers were hoping for a sweet spot where the young whale slowed down enough for them to help but was not so tired its own health was at risk.

“This whale is young, and it has been moving quite erratically. Yesterday, it was witnessed thrashing about a lot and quick changes of directions and things like that, so it was a really risky and dangerous situation for anybody trying to disentangle that whale yesterday,” she said.

“Today, it is witnessed moving more slowly at times … but then it does seem to have bursts of energy and and it’s moving quite quickly around as well, so which just does make it a bit more tricky for those who are trying to rescue it.”

-with AAP