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Hector's Dolphin Satellite Tagging: Q&As


Hector's Dolphin Satellite Tagging: Questions and Answers

What is the status of the North Island Hector's dolphin?

The World Conservation Union - IUCN Specialist group have listed Hector's dolphin (Cephalorhynchus hectori) as endangered and the North Island sub-species, Maui's dolphin (Cephalorhynchus hectori maui), as critically endangered (see www.redlist.org). In New Zealand, the dolphin has been recognised by the Minister of Conservation as a threatened species in 1999 under the Marine Mammals Protection Act. This was a bipartisan decision as the process started under then Minister of Conservation Nick Smith just before the 1999 election and was finished by former Minister, Sandra Lee.

So why are they recognised as threatened?

The North Island sub-species is estimated to number fewer than 100 individuals. The last complete survey of the area was carried out in 1985 (Slooten and Dawson 1988), which gave an estimate of about 130 dolphins. Since then there have been several smaller surveys and these found very few animals, under 100 (Russell 1999).

The South Island sub-species is divided into four populations. The West Coast of the South Island population is the largest. The Banks Peninsula population is small, about 800. Given new aerial survey information showing that more of the population is found outside the sanctuary (Slooten, Rayment and Dawson 2003) the population has a 60 percent risk of declining. Such an at-risk population should not be used for an invasive technique where alternative survey methods exist.

Satellite tagging is unnecessary - other methods are faster, more accurate and provide greater coverage

The Department of Conservation's Science and Research marine mammal specialists (Childerhouse and West 2004) recommended that "aerial surveys are to be preferred over satellite tagging". Further:

* The degree of protection given by current sea area closures to set netting and trawling should be determined by a series of aerial surveys.

* Dolphin use of harbours should be determined by the use of Porpoise Detection devices (PODs).

Winter and summer aerial surveys have already been carried out around Banks Peninsula. A summer survey has just been completed on the West Coast of the North Island and a winter survey is planned this year. This has been principally funded by WWF and the Ministry of Fisheries. This will produce information on dolphin range several years earlier than any tagging process.

Argos satellite fixes are not very accurate

These satellite fixes are not like GPS. As Childerhouse and West (2004) state the principle reasons for not recommending satellite tags "are the large confidence bounds expected to be associated with satellite fixes relative to the small protected areas (essentially 1nm and 4nm strips)..." Argos provides information on the accuracy of fixes but this over-estimates accuracy based on comparison with GPS fixes (see Le Boef et al (2000). Wildlife Computers, who make the tags, predict about one good satellite fix a day. A good fix will produce a range of accuracy up to 1.8km from the real site rather than the 350 metres claimed by Argos.

Tags are an invasive technique?

The proposal is to drill four holes in the dorsal fin of each dolphin and bolt the satellite tag to it. Hector's dolphin are the smallest dolphin which tags have been applied so they could only be small.

"Tag release is not an exact science"? So how long will these tags last?

The main manager of the application, Dr Stone, has clearly stated that "galavanic action will corrode the attachment and release the tag from the dolphin's dorsal fin after the batteries are expired". Dr Stone told the meeting at the Department of Conservation (17 February 2004) that this process "is not an exact science". In other instances of tagging larger dolphins a tag designed to last 180 days actually stayed on for 34 to 487 days. This trial proposes that the tag will last 130 days. Given the inexactness of the method these tags could well last longer than a year, which is beyond the life of the permit and the final report which the Department wants on the success of the trial.

Dolphins are lost after the transmitter fails?

The welfare of the animal has not been considered after the tag stops transmitting. Dr Stone has stated "it is very difficult to find an animal" once the batteries fails. He noted that removal of the tags has been carried out with large whales but was not successful with one of the other researchers (Dr Teilmann) when tagging harbour porpoises.

No statistics used in the trial

This trial has not been subjected to statistical analysis. There has been no quantitative risk assessment, despite several requests, and there has been no analysis presented of why three animals are needed. In fact the key researcher involved in the trial has stated that statistics is not needed in this case. The only statistical results presented were in the report by Childerhouse and West (2004).

Why no recovery plan?

Conservation groups have promoted the need for a recovery plan covering both sub-species of Hector's dolphin for over 4 years. The Department has in the last year worked on this tagging proposal rather than developing a recovery plan the key aspect of which would have been to assess the key questions about the dolphin which we need to answer.

Is Ethics approval for a different proposal?

The Animal Ethics approval is flawed as it approves a different project than that which was submitted to DoC for a permit. The Animal Ethics application states:

* That a permit has already been granted by DoC, which is clearly not true;
* That after programme battery life the "dolphin will be captured a second time to remove the data logger and transmitter". The DoC application is for the tag to fall off one the pins or bolts have rusted out.

* That it is necessary and there are no alternatives for gaining this information -clearly this is not the case. There are non-invasive methods that can produce positional information over a wider area and more accurately than the proposed satellite tagging (see Childerhouse and West 2004).

* There is no power analysis of the number of animals that should be used and there is no justification of the animal numbers apart from the statement that "The Department of Conservation have granted permits to capture three Hector's dolphins in Canterbury for a trial of this technique".

* According to the Massey University Code of Ethical Conduct (3 October 2003) "Endangered and threatened species should not be used unless the appropriate permits are obtained and the findings are expected to assist the survival of that species." Again this is not the case, there are alternatives and permits have not been granted. The National Animal Ethics Advisory Committee Good Practice Guide for the Use of Animals in Research, Testing and Teaching has a checklist for planning which includes "Can the aims be achieved without using animals?" Clearly the critical distributional information can be achieved without an invasive technique.

Ethics approval doesn't include the welfare of the dolphins?

The ethics approval has not considered what happens to the dolphin after the tags have been placed on the animal. At a recent DoC meeting (17 February) it was accepted by Dr Stone and the DoC staff present that the present proposal provides no method of determining the long-term welfare of the three tagged dolphins once the transmitters stop working.

What are the major human threats to the dolphins?

The major threats to the dolphins are:

* illegal set nets in the current closed area;

* that the closed set net area is not large enough and dolphins are at risk when they move out of it or into harbours where set nets are not prohibited;

* trawling in the closed area - in the South Island trawlers have caught Hector's dolphin;

* boats running over the dolphins in the harbour channels.

Aerial and boat surveys are the most effective method to assess these risks.

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