Stop press: Late on Thursday the whale carcass was floated off the rocks and towed to Bellambi boat ramp to be removed.

Surfers in the northern Illawarra are on alert as a dead humpback whale has washed ashore near Scarborough Beach.

The deceased whale was first spotted on Tuesday morning, tangled in a shark net placed offshore from Coledale Beach. Coledale is one of 5 beaches on the Illawarra coast and 51 in NSW fitted with a shark net during the warmer months.

The whale was migrating south and though its death appears to be due to the shark net that’s not yet confirmed.

(Khynan Gardner/ORRCA)

"It's all speculation at this point,” said Ashley Ryan, president of Organisation for the Rescue and Research of Cetaceans in Australia [ORRCA], “but it does look like the whale has died after becoming caught in the shark net. But without performing a necropsy, we won't be able to say for sure.”

"We've seen live whales in shark nets in NSW, but it's not very common for this to happen."

More pressing is what happened to the carcass. A combined effort between Marine Rescue NSW, Wollongong City Council, and NPWS, assisted by an ORRCA drone, spent hours trying to retrieve the carcass. However, the operation was made difficult with southerly winds and swell.

"It was reasonably close to the shore,” said Marine Rescue NSW Inspector Stuart Massey, “so around 3pm the decision was made to abandon the effort only due to safety." 

(Khynan Gardner/ORRCA)

Late on Tuesday the whale washed ashore 200 metres north of Scarborough Beach. With a run of small swell approaching, a second effort to tow the carcass will be made, though a quarter moon phase - which suppresses the high tides - will make boat retrieval difficult.

ORRCA is warning surfers to avoid the area because of an elevated risk of sharks as the body decomposes.

(Curtis Tredway/Facebook)

The NSW shark net program runs from September to April. Last season 223 animals were caught in the nets with only 11% being target species (white sharks, bull sharks, tiger sharks).

143 (or 65%) of those animals caught in the nets died. The rest were released

Two animals - a dusky whaler and shortfin mako - were caught in the Coledale net last season. Both died.

The Illawarra has a higher mortality rate than other regions with 39 animals caught during the season and only 8 surviving. With a 80% mortality rate, the region is 15% above the statewide average.