Bluebottle jellyfish stings are on the increase as the buoyant organisms float in from the Tasman Sea because of the high seawater temperatures.
Also known as the Portuguese man-of-war, bluebottles are not proper jellyfish, so their sting treatment differs from that for true jellyfish species' stings.
Surf life-savers at St Clair and St Kilda beaches treated more than 30 people on Tuesday for bluebottle stings.
St Clair surf life-saver Max Corboy said there had been fewer people coming to the club house with stings yesterday but there were still bluebottles washing up on the beach.
There had been no serious reactions to the stings, Mr Corboy said.
''We just get them coming up to the clubhouse and we flick off the stingers with a credit card and then pop them [victims] in the hot shower.''
According to the Ministry of Health, bluebottle stings should not be treated with vinegar as with actual jellyfish stings.
They suggest removing the stings with a towel or gloves and washing the area with sea water, or if available, water as hot as the person can cope with.
Bluebottle stings do not usually result in a serious allergic reaction or anaphylaxis.
Department of Conservation biodiversity manager Jim Fyfe said he noticed a rise in both the number and size of bluebottles from previous years.
High temperature flows coming in from the Tasman Sea were most likely where the bluebottles were coming from.
''We get them almost every year but they are much bigger than we usually see down here.''
Occasionally, poisonous box jellyfish would also wash up on Dunedin beaches but were very rare, Mr Fyfe said.
