Maui's dolphin surveys

Since the expansion of the set net closure between Maunganui Bluff and Pariokariwa Point in 2008, the Department of Conservation (DOC) has continued to collect information regarding the current distribution of Maui’s dolphins (with the support of the Ministry for Primary Industries). This includes how far they live up and down the west coast of the North Island and also how far they range offshore.

We have also looked into their utilisation of the North Island west coast harbours. It is important to have a firm idea of where the dolphins range so that we can effectively manage both fishing and non-fishing threats within the entire range of the dolphins.

One of the outcomes of the Maui’s dolphin Risk Assessment workshop was an updated understanding of Maui’s dolphin distribution. The distribution, from north of Kaipara Harbour to Whanganui, was developed from a combination of empirical evidence (data from nine aerial and biopsy surveys conducted between 2000 and 2012) and expert judgement, taking into account public sightings and strandings data. See distribution map (PDF, 270K)

Maui dolphin survey, west Coast of the North Island between Kaipara harbour and New Plymouth. Photo: Martin Stanley.
Maui dolphin survey, west Coast of the North Island between Kaipara harbour and New Plymouth

Surveys

DOC has undertaken a number of different opportunistic and systematic surveys since 2006 including ‘alongshore surveys’ (up and down the coast) and ‘offshore surveys’ (parallel transects).

  • Systematic annual offshore surveys completed 2006 - 2009
  • Alongshore aerial surveys 2012 - 2013, and
  • Boat-based surveys during summers 2010 - 2013.  

Alongshore surveys from 2006 - 2013 are used to find out more about how far Maui’s dolphins move up and down the coastline, whereas offshore surveys tell us about how far offshore the dolphins range.

Key findings

  • These alongshore surveys have covered an area as far north as Baylys Beach in Northland and as far south as Hawera.
  • The southern-most survey sighting was during 2009 at Tirua Point, about 16 nautical miles (nm) south of Kawhia Harbour. The northern-most aerial sighting was about 1nm off Piha beach, but a boat survey in 2010 recorded Maui’s dolphins 4nm south of the Kaipara Harbour mouth.
  • Offshore sightings have confirmed sightings of Maui’s dolphins between 4 and 7 nm offshore.

Summary by season

2012 – 2013 

Boat-based surveys undertaken 

Awakino to Oeo boat survey map (PDF, 496K)

Taranaki boat surveys summary report (PDF, 77K)

  • Six separate boat surveys were undertaken between Awakino and Oeo from December 2012 to March 2013:
    • New Plymouth to Awakino (4 trips)
    • New Plymouth to Oeo (1 trip)
    • New Plymouth to Opunake (1 trip)
  • A total of 836km, or 464.5nm was surveyed with a total of 26 hours and 2 minutes of on-effort observation.
  • No Hector’s/Maui’s dolphins were sighted.

Alongshore aerial surveys undertaken

Alongshore aerial survey map (PDF, 508K)

Taranaki aerial surveys summary report (PDF, 77K) 

  • Five separate alongshore aerial surveys were undertaken using a fixed-wing aircraft. Surveys departed New Plymouth Airport north to Awakino, returning to the airport to re-fuel. The aircraft then flew south to Hawera, again returning to New Plymouth Airport.
  • The aircraft flew within approximately 1 and 2nm from shore.
  • A total of 1811km, or 1006nm, was surveyed with a total of 12 hours and 6 minutes of on-effort observation.
  • No Hector’s/Maui’s dolphins were sighted.

South Kaipara Head to Mokau

Auckland boat surveys summary report (PDF, 104K)

  • Three separate boat-based surveys were conducted between South Kaipara Head and Mokau during March and April 2012:
    • Raglan to Manukau
    • Raglan to Mokau
    • Manukau to Kaipara
  • A total of 657.4km, or 355 nautical miles (nm), was surveyed with a total of 27 hrs 50 minutes of on-effort observation.
  • Thirteen Maui’s dolphin groups were sighted. 28 were recorded as adults, 12 as juveniles and 2 as calves. On analysis of body markings and dorsal fin photographs, it was confirmed that one adult Maui’s dolphin had been resighted, reducing the actual numbers of adults encountered to 27.
  • The northern most Maui’s dolphin was observed approximately 3.7nm south of Kaipara harbour mouth.
  • The southern most sighting was 9nm south of Manukau harbour mouth.
  • Maui’s dolphins were observed in the depth range of 5.5-12.2m of water.
  • The Maui’s population encountered when compared to a comparable survey in 2012 provides the same numbers of adults (27) and juveniles (12), but with the addition of 2 calves (as none were observed in 2012).

2011 - 2012 

Tirua Point to Opunake

  • Seven separate boat surveys were undertaken between Tirua Point and Opunake from October 2011 to April 2012:
    • New Plymouth to Tirua Point, return (3 trips)
    • Awakino to New Plymouth (2 trips)
    • New Plymouth to Opunake, return (2 trips)
    • No Hector’s/Maui’s were sighted.

Woody Head, Raglan to South Manukau Heads, Auckland

  • One boat-based survey was conducted between Woody Head and Manukau Heads during March 2012.
  • A total of 235km, or 126.8nm, was surveyed with a total of 10 hrs 36 minutes of on-effort observation.
  • Twelve Maui’s dolphin groups were sighted. Twenty-seven were recorded as adults, 12 as juveniles and no calves were recorded.
  • The northern most Maui’s dolphin was observed approximately 5 km south of Manukau Harbour mouth entrance.
  • The southern most sighting was 8km south of Raglan harbour mouth entrance near Woody Head.
  • Maui’s dolphins were observed in the depth range of 9-14m of water.

2010 - 2011

Boat-based surveys undertaken. See Maui's dolphin abundance estimate.

2009 - offshore

  • This survey covered the area from Bayleys Beach to Kawhia Harbour.
  • There were 12 sightings made.
  • Nine sightings were within 1nm of the shore and two were between approximately 1 and 2nm from shore.
  • The furthest offshore sighting was recorded at 6.18nm.
  • The northern-most sighting was just south of the Kaipara Harbour mouth and the southern-most was midway between the Manukau Harbour and the Waikato River mouth.

2008 - offshore

  • This survey covered the area from the Kaipara Harbour to Raglan Harbour.
  • There were 9 sightings made.
  • Five sightings were within 1nm of the shore and 3 were between 3 and 4nm from shore.
  • The furthest offshore sighting was recorded at 4.3nm from shore.
  • The northern-most sighting was off the Kaipara Harbour mouth and the southern-most was midway between Raglan and the Manukau Harbour.

2007 - offshore

  • This survey covered the area from Muriwai to Carters Beach, just north of Raglan.
  • There were high concentrations of sightings between the Manukau Harbour and the Waikato River.
  • Nine sightings were south of the Waikato River.
  • Most sightings (11 out of 13) were made within 3nm of shore.
  • One sighting was recorded 4.05nm offshore, near Carter's Beach.
  • One sighting was from north of the Manukau Harbour, approximately 1.2nm offshore of Muriwai Beach.

2006 - offshore

  • This survey covered the area from Muriwai to Carters Beach, just north of Raglan.
  • Sightings were widely distributed between Muriwai and Carter’s Beach, with possible sightings up to 10nm offshore.

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Contacts

Whare Kaupapa Atawhai / Conservation House
Phone:      +64 4 471 0726
Email:   Enquiries@doc.govt.nz
Full office details

Email: marine@doc.govt.nz 

To report whale or dolphin strandings phone 24 hour emergency number: 0800 DOCHOT (0800 362 468) 

In the North Island, immediately report any Hector’s/Maui’s dolphin sightings south of Awakino (near the Taranaki – Waikato boundary) and on the East Coast.

DOC is especially interested in these sightings as they represent areas of the range of Maui's dolphins where genetic samples are limited. How you can help.