Guest Post: Maui’s Dolphins

A guest post by Keith Mawson of Egmont Seafoods:

Scientists telling fibs about Maui’s dolphins

In 2003 the government banned in the Maui’s dolphin habitat off Auckland and Waikato.  No Maui’s have been recorded as harmed by fishing since then.

Yet this is not what the experts in the International Whaling Commission were told as they voted against New Zealand at the IWC meeting in Slovenia.

The IWC relied on a paper presented to its Scientific Committee in 2013 which stated there was a yearly documented death rate of the endangered Maui’s from fishing.

It was written by Dr Barbara Maas, who works in London for NABU International, a conservation organisation. 

She reported to the IWC that there was not only a recorded Maui’s death rate from fishing, but that in 2008 it increased.

Since the 2008 protection measures were introduced, the number of stranded and reported bycatch cases has increased slightly (Slooten 2013). Between 1970 and 2008 an average of 1.00 entangled Maui’s dolphin was recorded per year. This figure increased marginally to 1.33 dolphin deaths per annum between 2009 and 2012.

Maui’s are clearly threatened subspecies of dolphin. Though the well-known number of 55 Maui’s adults is an estimate, the real population total is probably not too far off this.

Were Maas’ figures to be true, (though she states the figures come from Otago academic Liz Slooten but Maas provided no footnote reference) there would have been eight dead Maui’s dolphins from fishing since 2008, and nearly another 40 back to 1970.

If fishing was killing them at the stated rate, and expanded into a theoretical and often cited multiplier total of 4.97 per year, then something would need to be done.

But the figures, though worked out to the seemingly scientific second decimal point, are bogus.  A Slooten paper which is the probable source, states the numbers are taken from a DOC database. 

But the DOC database has no such information.  The IWC has been misled.

The information DOC holds is that in four cases, between 1921 and 2002, fishing may have killed a Maui’s.  Two were ‘possible’, one ‘probable’ and one ‘known’.

There is no yearly rate at all.  There are only four instances of fishing possibly killing Maui’s since records were first taken 93 years ago.  It is actually the confirmed reason in only one of these four cases.

Even more significantly, the most recent fishing implicated case was in 2002.  In 2003, the government imposed set net and trawl restrictions in the known Maui’s range – encompassing the areas where these four mortalities had occurred. 

So set net fishing had at most a questioned and minor impact on Maui’s before 2003, but no effect at all has been evident since.

There is no record of any Maui’s ever being caught in a trawl net either.

It is well known where most of the Maui’s live. They frequent shallow waters 30 kilometers north and south of the mouth of Waikato River, with some as far north as the Kaipara.

The occasional migration of Hector’s dolphins from the South Island confuses this picture. Both belong to the species Cephalorhynchus. They look exactly the same.

When Maui’s were categorised as a subspecies of Hector’s dolphins in 2002, the scientists believed the population had been separate since the end of the last ice age thousands of years ago.

Imagine the surprise when in 2010 sampling of DNA found a couple of Hector’s alive right in the core of the Maui’s habitat.  Theoretically they should not be there.  But they are.

Since physical separation of Maui’s and Hector’s no longer applies, genetic distinctions and old fashioned physical measurements are the remaining criteria for distinction.  It’s a weak case, since there is no more genetic difference discovered between Maui’s and Hector’s than there is between at least 26 subsets of Hector’s themselves.

The latest government commissioned survey information of Hector’s is that there are more than 9,000  off the East Coast of the South Island, with other populations off the West Coast and Southland, making a total population of about 14,500.  They are not at risk of extinction.

Dolphin campaigners will not accept this figure and still insist the total Hector’s population off the South Island is not much more than 7,000. 

This much lower number is used in the recent Economists at Large analysis of the Maui’s and Hector’s, which was commissioned by the Whale and Dolphin Conservation organisation.  The report did not mention that the figure is at best a contested estimate.

The Economists at Large document includes a map of where they think Maui’s and Hector’s live and which the authors want for a dolphin sanctuary.   The map depicts three ostensible migration routes of Maui’s going to the South Island.

The map is a Pixar Animation level of imagination.  There is not a shred of evidence any Maui’s dolphins have ever crossed to the South Island, let alone that such migrations are studied and frequent enough to justify a number of detailed route maps.

There is no evidence either that the Maui’s and Hector’s breed with each other, so the demand for a huge no-fishing ‘breeding corridor’ between North and South Islands is another fantasy.

But back to the facts.  Five Hector’s DNA samples have been collected along the Wellington coast to Taranaki since 1967.  No Maui’s DNA has been found south of Kawhia, well up into Waikato, since 1989.

In November 2011 there was a Hector’s sighting in Wellington Harbour.  Over that summer there were sightings up to Taranaki and Hawkes Bay.  There were two sightings between Hawera and Whanganui – the only ones ever recorded.  A beach-cast DNA confirmed Hector’s was found at Opunake in April 2012.

Crucially a dolphin was captured and killed in a fishing net in January 2012.  The regulations prevented any samples being taken and it was returned to the sea.  We will never know whether it was a Hector’s or a Maui’s.  DOC thinks it was a Maui’s. The Ministry for Primary Industries thinks the chances of it being a Maui’s or Hector’s are even.

But in the popular mind it was a Maui’s.  Advocate scientists successfully had more fishing restrictions imposed later in 2012 and then more again the following year.

As a result of these unjustified restrictions the fishing industry along this coast has contracted.  Workers have been laid off.

A risk assessment panel in 2012, with handpicked dolphin advocates, declared there to be Maui’s populations, not just off Taranaki, but as far south as Whanganui which needed protection from fishing effort.

The evidence though is increasingly that in some, but by no means all, summers there is something which drives or lures a very small number of Hector’s from the South Island to the North Island, to Wellington, along the Kapiti coast and then sometimes further north again. 

Off Taranaki, more than 1,000 MPI observer days have been spent on fishing vessels looking for Maui’s in the past two years.  A similar time has been spent by independent observers on oil exploration vessels.  DOC has used boats and aircraft to find Maui’s or Hector’s in the region.

They have seen none of either.  If the expert panel in 2012 had been anywhere near correct in its population estimates then there would have been at least dozens of Maui’s sightings.

Undeterred, the experts keep on supplying their opinions to the IWC. This year the Scientific Committee was informed that the number of Maui’s killed by fishing between Hawera and Whanganui could exceed one per year. 

Based on established ratios of population to capture from the Hector’s in South Island waters this death rate would mean a population of some hundreds of Maui’s would need to exist between Hawera and Whanganui.

No scientists have seen a Cephalorhynchus (Hector’s type) here.  There have only been two public sightings ever.  Both were following Hector’s presence along the coast to the north and south in the 2011-2012 summer.

The panel has been proven quite wrong in another respect as well.  It concluded that the rate of deaths in Maui’s due to disease was less than one every 100 years, so certain was it that fishing, both set net and trawl, was the culprit of population decline.

The panel did not consider three post-mortems which were being conducted on three Maui’s at Massey University.  The cause of death for two of them was established as Toxoplasmosis, a protozoan disease originating from land animals, with cats playing a critical role in the disease life cycle.

The diagnosis resulted in the expert panel’s allocation of disease blame to be used up for the next two centuries and beyond.

Hector’s dolphins dissected at the same time were also riddled with toxoplasma. The species has shown to be more vulnerable to this disease than other types of dolphin.

Unlike the many petitions which have been raised to call on the government to multiply the sea area closed to fishing, none are circulating wanting the government to fund research on Toxoplasmosis.

There is no research programme for Toxoplasmosis, which has been proven to kill Maui’s, yet many calls for more restrictions on fishing, for which there is no evidence that it is causing Maui’s any harm at all.

The conclusion must be that either it’s easier to run a blame-game campaign on human activity, than it is to target disease infection from land animals.

More specifically, is that the campaign to save the Maui’s is more generated by antipathy towards people earning a living from the sea, than it is to actually saving the Maui’s.

Over the past few months Maui’s campaigners have refocused their targeting on the petroleum industry off Taranaki.  There is no evidence that oil exploration or extraction has harmed a single Maui’s in half a century of activity in the region.

But it is interesting to note how the argument on where the Maui’s are supposed to be living, is manufactured to suit the activity being cited to cause the threat.

When fishing is targeted, the Maui’s population is described as being up to three-quarters of the way round the North Island and even off the South Island.  That is, where there is fishing.

But now, when the target is the petrochemical industry off Taranaki, the Maui’s population spread has been totally reinvented.  The new claims are that ‘their entire population [is] residing in a small sanctuary established in 2008 off the west coast of the North Island’.

We all want to see the Maui’s population flourish.  We do not want it to become extinct.  This will mean boring science stuff, such as investigating how the Maui’s get diseases from the land, or how their reproduction might be helped.  None of this is being done.

Instead, ideological targeting masquerading as scientific objectivity will not help them.

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