Hector's dolphin in Akaroa Marine Reserve
Image: Danica Stent | ©


We maintain a database of incidents based on reported events. Incidents include dead or stranded Hector’s and Māui dolphins and those caught by fishers.

Reports may be of dolphins:

  • alive stranded on the beach
  • injured but alive at sea
  • washed up dead on beach
  • found floating dead at sea or
  • caught during commercial or recreational fishing (bycatch), may be dead or released alive.

Incident updates - includes pathology reports

Download a complete copy of DOC’s national database for Hector’s and Māui dolphin incidents, it is updated quarterly:

Spreadsheet of Hector's and Māui dolphin incidents: 1921 to 17 March 2024 (XLS, 311K) 

Some incidents may involve multiple animals, so the data is provided in two tabs: one for the event information, and one for the individual information.

With the 'individuals' tab, data is displayed as one row per individual. Use the 'MarMam observation ID num' to identify individuals involved in the same event. Event information will be the same for each individual in that event.

For more information about the data, see the user information guide (PDF, 472K).

Annual tables

The links below contain annual tables with details about Hector’s and Māui dolphin incidents. We update these tables as soon as possible after receiving details about an incident.

Where reports come from

Our work to learn more about the threats to these dolphins relies on prompt reporting of dead dolphins by members of the public. The database tends to have more reports from areas that have higher visitor numbers.

We also rely on reports from fishing vessels that have caught dolphins – this is a legal requirement.

Currently, investigation of all Māui and Hector’s dolphin mortality includes:

  • photographing the dolphin as it was found

  • taking a genetic sample and measurements

  • post mortem (necropsy).

Necropsy programme

Learning about why dolphins die can help us manage the threats to them. This requires a post-mortem examination (necropsy). The aim of the post-mortem is to try to determine the cause of death.

The post-mortem involves a physical (gross) and microscopic (histological) examination. A report is submitted for each examined dolphin with the results of the post-mortem (pathology report). These reports are made available in the annual tables above. The examiner classifies the post-mortem results as one of the following options:

  • Entanglement (Known, Probable, or Possible)

  • Other human induced (Known, Probably, or Possible)

  • Vessel strike

  • Natural causes (General, Maternal Separation, or Disease)

  • Unknown trauma

  • Euthanasia

  • Indeterminable (unable to be determined)

  • Other

The cause of death may be from a combination of several factors.

It is not always possible to determine the cause of death, and factors such as decomposition, and freezing can contribute to this.

Dead dolphins won't always be sent for necropsy due to decomposition levels, or if the body is lost to the tide before it can be collected.

What the database contains

The database contains a variety of information about each dolphin, such as:

  • type of incident

  • sex

  • length

  • where it was found

  • any background information about the incident

  • necropsy results or suspected cause of death.

The database also contains results from any DNA analysis done. This analysis can provide genetic sex and population information (haplotype). A DNA sample is required to determine between the Hector's and Māui dolphin subspecies.

Haplotypes are portions of DNA that are only passed on by females, so each dolphin has the same haplotype as its mother. Haplotypes are assigned letters of the alphabet. There are 20 haplotypes in Hector's dolphins, and one that is unique to Māui dolphins (G). 

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