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Welcome to the new format of Māui Watch!

Issue 6

Winter 2016

Māui dolphin: exploring its southern range

 

Since 2012, DOC Taranaki staff have carried out boat and aerial surveys of the elusive Māui dolphins along the Taranaki shoreline. This is just one part of work to better understand the southern extent of the Māui dolphin’s range.

The surveys complement an advocacy programme in Taranaki designed to encourage robust public and industry sightings. These programmes aim to increase understanding of Māui dolphin presence and habitat use in Taranaki waters, to inform decisions on how to best protect the population. The programmes will form an important body of information for the 2018 review of the Threat Management Plan.

Surveys take place from the air and at sea: four observers watch for dolphins from Hawera to Awakino, between (roughly) half to two nautical miles offshore. All marine mammal and basking shark sightings are recorded.

Boat surveys are particularly valuable as they allow biopsy samples to be taken from dolphin encounters, helping distinguish Māui from the Hector’s dolphins that occasionally swim among them. Aerial surveys give better visual and spatial coverage, but do not allow the collection of genetic samples.

Since 2012, we have surveyed the Taranaki area vigorously:  boats have covered 1,937 km of coastal waters, with 60 hours of observations, while aircraft have covered 7,663 km over 47 hours. See Figure 1 for survey tracks and sightings.

So far, however, no Māui dolphins have been sighted. Given the small population size, there is little chance of encountering Māui dolphins at the extremes of their range. Surveys are only a snapshot in time, and sighting distance is limited to a few hundred metres each side of boats and aircraft. Even if dolphins were present they could pass unnoticed. There are several validated public sightings of Māui or Hector’s dolphins in Taranaki.

 

Alongshore aerial and boat surveys for Māui dolphins 2012-2016

  Figure 1. 

 

Have you seen me?

 

ID: M031

Māui dolphin M031's recognisable dorsal fin, left side
Māui dolphin M031's recognisable dorsal fin, right side

Last seen: M031 was seen three times between Hamilton’s and Cochrane’s Gaps during the 2015 Māui dolphin survey. M031 was a new addition to the photo identification catalogue in 2015.

 

Recent sightings

 

Date: 13 March 2016

Number of dolphins sighted: 2

Location: Between Manu Bay and Raglan Bar

Graeme Cresswell considers himself very lucky to have had a visit in his boat from two Māui dolphins back in March. He got some great pictures!

Report māui dolphin sightings

Māui dolphin spotted by Graeme Cresswell on 13 March in Raglan
Māui dolphin spotted by Graeme Cresswell on 13 March at Raglan
 

Research update

 

Māui dolphin abundance estimates, and 'C-Pods'

Winter is keeping us busy: this is the time when fieldwork dies down and we collate, analyse and report on the data collected over summer.

In 2015 DOC, the Ministry for Primary Industries (MPI) and the University of Auckland kicked off the first season of a revised abundance estimate for Māui dolphins. In 2016, they undertook the second and final field season. Despite tricky weather conditions a successful season was completed, with 44 biopsy samples collected from dolphins between Kaipara Harbour and north of Raglan. Genetic analysis is underway and a new abundance estimate will be available later this year.

DOC and MPI are also trialling the use of C-PODs, which are able to detect the clicks used by the dolphins! We want to see if we can use these to determine where Māui dolphins hang out. A similar study was done between 2005 and 2008 using an earlier model called a T-POD.

A single Māui dolphin seen from a research vessel in the Māui dolphin core range
C-Pods are attached to underwater structures or weighted in the water column to detect underwater sound
 

Team Māui - Kristina Hillock

 

Kristina is a technical advisor in the Marine Species and Threats team, based in the Hamilton Shared Services office. Her role is varied but includes technical advice for marine mammal permits, wildlife permits, shark cage diving, marine biosecurity, benthic impacts and the Resource Management Act.

Prior to 2013, Kristina was involved in the DOC Māui dolphin recovery group, and helped out on the Māui abundance surveys in 2010 and 2011. Kristina is now Project Manager of the Hector’s and Māui dolphin threat management plan review.

Kristina Hillock

What work will you be doing on Māui dolphins?

Having only just taken on this role, I’m still getting up-to-date with everything. However, I’ll be involved with planning for the next MRAG meeting and getting the abundance estimate circulated and presented once it’s complete.

If a member of the public asked “What can I do?”, what would you say?

Reduce the amount of plastic in your life and how much is discarded and ends up in the ocean. Plastic is persistent, and degrades into smaller particles (microplastics) that accumulate in the ocean, and can be taken up by a wide range of marine organisms (including Māui dolphins) through the food chain. Microplastics are either potentially toxic themselves, or can absorb other toxic pollutants.

 

2015/16 summer sightings update

 

From October to April, DOC and WWF received 68 reports of Hector’s or Māui dolphins around the North Island (compared to 59 last year). Forty seven of these have been validated at scores of one to three, meaning they are likely to be accurate sightings of Māui or Hector’s dolphins. The rest are pending validation.

Fifty six of this summer’s sightings were within the known Māui dolphin range. The remaining 12 sightings were in Wellington, Hawke’s Bay, and the Bay of Plenty. Without genetic samples we are not sure if these dolphins are Hector’s or Māui – it’s possible the dolphins travelled up from the east coast South Island population.