Auckland beachgoers warned to 'exercise caution' as jellyfish bloom sees increased sightings around city's coastline

Stranded Lion's Mane Jellyfish on the sand on a beach in England - stock photo.
Stranded Lion's Mane Jellyfish on the sand on a beach in England - stock photo. Photo credit: Getty Images

Auckland beachgoers have been warned to "exercise caution" at the shoreline after an influx of jellyfish.

Auckland Council says a jellyfish bloom - referring to a substantial increase in a jellyfish population due to a higher reproduction rate - is responsible for the sudden number of sightings at the city's coastline. 

Several jellyfish resembling the lion's mane, one of the largest known species, have been spotted on north Auckland beaches in recent days. Pictures of the marine animals have been shared to community groups on social media, prompting varying reactions from locals. 

One woman warned residents to take care after spotting a lion's mane jellyfish washed up on Orewa Beach on Monday.

Auckland beachgoers warned to 'exercise caution' as jellyfish bloom sees increased sightings around city's coastline
Photo credit: Orewa/Red Beach/Silverdale NZ / Facebook

"They are beautiful but take care," she wrote in the Orewa, Red Beach and Silverdale Facebook community group on Monday, sharing several shots of the large pink-and-purple creature splayed out on the sand.

One local also shared a photo of a lion's mane washed up on neighbouring Red Beach, while another claimed she had spotted a similar jellyfish at Waiwera Beach that same day.

"There was just one very large one on Red Beach at 2:30ish this afternoon," one woman pitched in.

"Quite a few down there now," said another.

Auckland beachgoers warned to 'exercise caution' as jellyfish bloom sees increased sightings around city's coastline
Photo credit: Orewa/Red Beach/Silverdale NZ / Facebook

Reactions have ranged from awe to concern, with one branding the jellyfish "nasty" while another referred to them as "nature's art".

A warning is currently in place on the council's Safeswim website, urging Aucklanders to remain vigilant. The warning directs visitors to the Auckland Regional Public Health Service (ARPHS) website, which contains information on jellyfish stings and rashes.

According to the non-profit organisation Oceana, the lion's mane jellyfish harbours a powerful sting to catch its prey - but it's not lethal to humans. The species is predominantly found in the cold, boreal waters of the Arctic, north Atlantic and North Pacific Oceans, although they are also known to inhabit the seas surrounding Australia and New Zealand. 

Although its trailing tentacles can reach more than 10 metres in length, the largest lion's mane ever recorded had tentacles spanning 36.5 metres.

The Australian Museum advises giving the species "a wide berth".

"These jellyfish can deliver a painful sting and their fine tentacles are often difficult for swimmers to avoid," it says. "If stung, apply a cold pack to relieve the pain and seek medical attention if necessary."

Newshub has contacted the Department of Conservation for comment.