Introduction

This year’s Cook Strait Whale Survey counted 137 humpback whales, its highest tally in its 12 years and an encouraging indication their numbers are increasing in New Zealand.

The annual four-week Department of Conservation survey, which ended on Saturday (July 11), also broke its record for the highest number of humpbacks seen in a day with 27 spotted on Sunday June 21.

The highest number of humpbacks previously recorded in the survey was 106 in 2012 with the second highest, 92, last year. The previous highest daily tally was 21 humpbacks in 2012.

A surprise sighting during the survey was a rare white humpback whale spotted on Sunday July 5. It was identified by its distinctive dorsal fin as being the famous Migaloo, a whale that usually migrates past Australia.

Another special sighting was a newborn humpback calf on Tuesday July 7, only the second reported in New Zealand. The survey also saw the first recorded humpback baby in 2010.

Blue and sperm whales and a southern right whale were also seen by the survey team.

The DOC research in partnership with OMV New Zealand aims to estimate size of the New Zealand humpback whale population and is assessing humpback whale recovery since commercial whaling ceased in 1964. The annual surveys are timed for humpback whales’ northern migration from Antarctica to warmer South Pacific breeding grounds.

Survey leader Nadine Bott said it was busy but a buzz for the survey team to see as many whales as they did.

“It is exhilarating seeing the whales from our boat – we never get sick of it.

“The higher number of humpback whales being seen indicates the New Zealand population is recovering but we are not yet seeing the extraordinary rates of increase they have in Australia of around 11% a year. Perhaps that is something we will enjoy in our waters in the future.”

The survey is carried out with the help of volunteers including six former whalers who lead the whale spotting from a high point on Arapawa Island overlooking Cook Strait.  Whales seen are approached by boat to collect photos and skin samples using a biopsy dart tool that are used to identify individual whales.

“The ex-whalers are highly experienced and committed and have been invaluable to the project, especially our success in observing so many whales,” said Nadine.

“I am very grateful to OMV New Zealand for its significant contribution to the research project. It has enabled the survey to continue for the past eight years, allowing us to track the recovery of these amazing animals in our waters.”

Concerningly, two humpback whales were seen in separate encounters this year with craypot line caught on them and line and buoys trailing behind. The two entangled whales were moving too fast for a specially-trained DOC whale disentanglement team to have time to get to them and try to cut the line off them.

Humpback whales’ inquisitive nature, large flippers and tail, and their propensity to roll makes them particularly vulnerable to getting caught in craypot lines as they migrate along the New Zealand coast.

People setting craypots can reduce the risk of whales getting entangled in them by minimising floating slack craypot line, allowing only enough for tidal action. Avoiding setting pots during June and July in offshore deeper water would also significantly reduce the risk.

A humpback what slap its tail.
A humpback what slap its tail

Humpback whale tails.
Humpback whale tails

Additional information

  • Humpback whale recovery will be assessed by comparing numbers seen in the surveys to whalers’ records of humpbacks in Cook Strait from the 1950s and early 1960s. 

  • Skin samples and photos that identify individual whales are checked against photos and genetic samples from whales across the South Pacific for matches. This shows humpback whales seen in New Zealand have also been seen off the east coast of Australia and around New Caledonia. 

  • DNA testing has shown four humpback whales have been seen twice during the 12 years of the survey. 

  • The genetic information collected is also used to find out more about the genetic diversity of humpback whales in New Zealand. 

  • The survey initially ran for two weeks and whales recorded in those years were:
    • 2004: 25 humpbacks with another six large whales seen, some later identified as blue whales from photographs
    • 2005: 15 humpbacks
    • 2006: 18 humpbacks
    • 2007: 41 humpbacks and one southern right whale

  • OMV New Zealand sponsorship enabled the survey to increase for four weeks from 2008. Whales recorded in the survey from that time were:
    • 2008: 40 humpbacks and four pygmy blue whales
    • 2009: 49 humpbacks and one sperm whale
    • 2010: 70 humpbacks, including a newborn, two sperm and three minke whales
    • 2011: 73 humpbacks, with blue and sperm whales and orca also seen.
    • 2012: 106 humpbacks
    • 2013: 59 humpbacks, with blue whales also seen
    • 2014: 92 humpback whales
    • 2015: 137 humpback whales, and blue and sperm whales and a southern right whale
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