'Sudden increase' in blue whales spotted in Auckland's Hauraki Gulf

Thursday, 19 July 2018

The group was spotted feeding in the Hauraki Gulf.

Several blue whales, including a mother and a calf, have been spotted in the Hauraki Gulf.

Four of the 100-tonne mammals were spied blowing jets of mist, diving and feeding in the waters around Tiritiri Matangi Island on Wednesday afternoon.

Two more were also spotted by Auckland Whale and Dolphin Safari staff in the past week, leaving the crew baffled at the sudden increase in sightings.

The mother even lifted her tail out of the water as she dived, a relatively rare sighting.

Skipper Andy Light said there were usually only about 15 sightings a year, so six in one week was relatively unheard of.

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Blue whales have an average lifespan of about 80 to 90 years, and can reach up to 30 metres in length.

'It's unlike any previous year in the company's 18-year history, it's awesome to see so many blues whales up here.'

He said the mother was feeding, most likely on shrimp and krill, next to her calf, which was 'frolicking' on the surface.

The blue whales were diving and feeding around Tiritiri Matangi Island in the Hauraki Gulf.

'They're probably migrating up from Antarctica up to their breeding ground, but stopping over here to feed first.

'The mother whale even at one point lifted her flukes [tail] out of the water as she dove – an even bigger rarity due to the shallow depth of the area.'

On-board marine research and conservation officer Catherine Lea said it was only the second blue whale the crew had observed doing this.

The vessel, although primarily a tourist boat, sends sightings data to Niwa and blue whale researchers in order to further the knowledge about the species.

'We pride ourselves … in being actively involved in contributing towards scientific research to help better understand individual species and marine ecosystems as a whole,' Lea said.

The whales were spotted from the Auckland Whale and Dolphin Safari boat on Wednesday.

Two sub-species of blue whale exist in the Southern Hemisphere, including the Antarctic blue whale and the slightly smaller pygmy blue whale.

The blue whale is the largest animal in the world, normally measuring 20-25 metres and weighing around 150,000 kilograms.

A mother spotted with a her calf was about 8 metres long.

Despite its name, the pygmy blue whale is still large in size, normally measuring 20-24m and weighing around 140,000kg.

Light said it was 'highly likely' those the crew had spotted were of the pygmy blue whale variety.

'Regular' blue whales were considered endangered but the jury was still out on whether pygmy blue whales were also endangered - the result of significant data gaps, as described by The International Whaling Commission.

Research published in the Endangered Species journal, estimated 718 pygmy blue whales currently call New Zealand home.

The safari catamaran usually spots resident Bryde's whales in the gulf, a slightly smaller species of baleen whale, as well as dolphins and orca.

BLUE WHALES

The average lifespan of a blue whale is about 80 to 90 years, and they can reach up to 30m in length - more than two buses long.

They are the largest animal on earth and also the loudest - their cries can be louder than a jet engine, according to National Geographic.

They can weigh up to 173,000kg, but average about 100,000kg.

Light said it was difficult to estimate how many there were in the wild due to their transient nature and because whale population studies are relatively new.

But he said he understood there were about 10,000-25,000 individuals worldwide.

'It certainly is extremely rare to see them on New Zealand's east coast.'