Foot-dragging over a toxic threat to dolphins might relate to NZ’s sacred cow of pets – cats. David Williams reports
The announcement was incongruous.
A $7.1 million programme, announced in last week’s Budget, would help save Māui dolphins, the critically endangered species found off the west coast of the North Island.
While that’s a tiny amount in the overall $400 million lift in Department of Conservation spending, the programme was deemed so important a picture of Māui dolphins adorned the ministerial press release.
“As well as protecting species on the land, DOC will also be taking measures to reduce the risk of extinction of key marine species such as Māui dolphins and migratory seabirds,” Conservation Minister Kiri Allan said.
A crucial element, according to Budget documents, is researching the risks to Māui from toxoplasmosis, a potentially fatal parasitic disease. (Toxoplasma gondii is the parasite, the “egg” carrying it is called an oocyst, and toxoplasmosis is the disease.)
Yet money for the programme, known as “reducing extinction risk for flagship marine species”, won’t start flowing until mid next year.
What? Isn’t being on the brink of extinction kind of urgent?
It’s estimated there are only 54 Māui dolphins aged over 1 year. (There are still about 15,000 Hector’s dolphins, close relatives of Māui which live mainly around Te Waipounamu, the South Island.)
DoC’s toxoplasmosis action plan for Māui and Hector’s dolphins, published two years ago, says the disease “is a significant cause of population decline” and failure to take effective action “will increase the risk of extinction for Māui dolphins”.
Yet there was no Budget money for research in the next financial year. (DoC clarifies there’s $30,000 set aside for toxoplasmosis research in 2022/23.)
Elizabeth Heeg, DoC’s aquatic director, maintains its work on toxoplasmosis is urgent, “as it represents an extinction risk to the nationally critical Māui dolphins, and is probably the largest unmitigated threat to the dolphins”.
However, she somewhat undercuts that by restating the action plan’s goal, to reduce Toxoplasma loading to the marine environment – by 2035 – so dolphin deaths from toxoplasmosis are “near zero”.
There’s a bunfight in the background.
Some dolphin experts and conservation advocates say there’s only weak evidence toxoplasmosis, or “toxo”, as it’s known, is a serious issue. DoC can’t have it both ways, they say.
“If you take at face value that toxoplasmosis is this great threat, then, with it comes a responsibility to act on it, and we’re not seeing that action,” says Christine Rose, chair of Māui and Hector’s Dolphin Defenders.
Correspondence released to Rose under the Official Information Act (OIA) reveals more about DoC’s response to the disease, including tensions over which agency is responsible.
These documents also point to what seem to be the elephant in the room: cats.
Felines are the main vector for toxoplasmosis. The parasite, T. gondii, reproduces in cat guts and is spread through eggs, known as oocysts, in faeces. Cat poo in soil and freshwater can infect birds and mammals, including humans, with toxoplasmosis for up to two years, while oocysts are infective in seawater for at least six months.
Other warm-blooded animals, such as rats, mice and rabbits, can be parasite “reservoirs”.
Toxoplasmosis can kill – not just dolphins, but people, too.
(It can induce miscarriages and cause blindness. However, as a 2013 study puts it: “T. gondii readily infects humans, but clinical illness is relatively uncommon.”)
One of the main priorities in DoC’s draft science plan is finding “hot spots” of oocysts, with particular interest in the Waikato and Manukau catchments – as they border the North Island’s west coast, where Māui are found.
The research is akin to Covid for cats. Where are the super-spreader events? What is the prevalence of deadly variants? Do some cats shed higher loads than others?
Once the threat is established, management options include planting along waterways, to trap the oocysts, humanely culling feral cats, and restricting domestic moggies.
That possibly brings into play the sacred cow of New Zealand pets, domestic cats – about 40 percent of households have at least one. Get it wrong and you might find yourself sharing the fate of former politician Gareth Morgan – becoming deeply unpopular, at least temporarily.
“If no one will take ownership then we are in real trouble.” – Anton van Helden
There’s the suggestion from departmental emails that DoC wants to refer cat management to other agencies – something resisted by some staff.
“Is it in the too hard basket or we are more focused on other pest species?” asks principal science advisor Graeme Taylor, a DoC veteran, in an email to marine science advisor Anton van Helden last November.
No single agency has a complete mandate to manage feral cats, Van Helden writes. “Everyone is waiting for someone else to take the lead.”
How do you manage a problem that starts on land, often in someone’s house, then shifts to public land, through to rivers and streams bordering land owned privately, and local and central government agencies, and then on to the sea, affecting a critically threatened dolphin?
DoC manages natural and historic resources, including Hector’s and Māui dolphins, the Ministry for Primary Industries (MPI) manages the effects of fishing on protected species, and regional councils provide for the protection of habitat for indigenous fauna and flora. Local councils set their own bylaws.
This agency overlap was one of the reasons a National Cat Management Strategy Group was formed in 2014, with a strategy released two years later calling for cat curfews, mandatory microchipping and desexing.
Van Helden, the DoC science advisor, says finding a responsible agency is a critical issue that needs to be addressed. “If no one will take ownership then we are in real trouble.”
(Heeg confirms DoC doesn’t have a feral cat management strategy, “just as we do not have national strategies for many pest species”.)
Writing directly to Van Helden, Taylor says if people understood the risks of toxoplasmosis to humans there’d be more public acceptance of cat control.
“Gareth Morgan did drive the argument for a while but it slipped off the radar once more,” Taylor writes. “There is a compelling case to pursue feral cat control, eradication on islands, and better ways to suppress the parasite in companion animals.”
Despite that, agencies seem worried cat control will turn toxic with the public. Considering the survival of an endangered dolphin is at stake, should that even matter?
Fishing threat reduced ‘almost to zero’
The OIA documents show the department takes toxoplasmosis very seriously.
Talking points prepared for Kiri Allan, ahead of a NZ Conservation Authority meeting last December, say an expansion of areas closed to set-net fishing and trawling, implemented in October 2020 with the aim of reducing the risk of fishing-related deaths, effectively reduced the threat of fishing to Maui dolphins “to almost zero”.
(That assessment is “complete nonsense”, according to dolphin expert Liz Slooten, a retired marine biologist. “That’s basically PR.”)
Katie Clemens-Seely, manager of DoC’s marine species team, tells the minister’s office: “Our primary focus now is to address the threat of toxoplasmosis to the dolphins.”
However, little is known about how toxoplasmosis gets from cats on land to dolphins at sea.
Now, the department is consulting mana whenua on its draft toxoplasmosis science plan, which will be followed by a management strategy. Further set-net fishing and trawling restrictions could be in the wings.
Allan’s discussion with the Authority was no doubt prompted by its letter sent a month earlier, to her and David Parker, Minister for Oceans and Fisheries, calling for proper funding and resourcing of toxoplasmosis work, and more urgency on its five-year research plan.
“Authority members are extremely concerned about this road to possible extinction could happen on their watch,” chair Edward Ellison wrote.
Toxoplasmosis attracts strange bedfellows, it seems. In April, Ellison’s letter was highlighted in a press statement entitled ‘Are Ministers ignoring Māui advice?’ from Seafood NZ, which represents the fishing industry.
Dolphin expert Slooten, Emeritus Professor at University of Otago, has an explanation: “The whole toxo thing was dreamt up by the fishing industry”.
This scientific spat has hit the headlines before but it’s worth covering the basics.
Slooten says there isn’t a single marine mammal species in the world on which you could say toxoplasmosis has had a “population-level effect”. T. gondii is so widespread it has been described as probably the world’s most successful parasite. A third of humans are thought to be infected by it.
The evidence toxoplasmosis is killing Māui and Hector’s dolphins is “very, very weak”, Slooten says, and relies on a tiny sample of dolphin carcasses. Between 2007 and 2018, veterinary pathologists examined 31 adult native dolphins that didn’t have fishing-related deaths. Nine died from toxoplasmosis.
Slooten compares the situation to examining the bodies of former rest home residents and professing there’s a pneumonia outbreak across the whole country.
“The whole thing is complete nonsense. You can’t just base this on a bunch of dead dolphins picked up off a beach.”
Rose, of Māui and Hector’s Dolphin Defenders, describes toxoplasmosis as a convenient bogeyman.
Slooten is firm – fishing is the biggest threat to Hector’s and Māui dolphins, and the most important move to save them from extinction is to ban trawling and set-nets from their habitat.
Rebuttal from Seafood NZ chief executive Jeremy Helson is too fulsome to repeat in full.
The idea the fishing industry made it up is “astonishing”, he says, and it’s “extremely frustrating” to have to defend “spurious accusations” when “this same industry, at much personal pain, has endured decades of closures to ensure the best outcome for the Maui dolphin”.
DoC and multiple overseas academics have done extensive research, so the idea the claims are nonsense, or toxo is a bogeyman, “whilst amusing, adds nothing to what is a scientific debate”.
Helson, who joined Seafood NZ from Fisheries Inshore New Zealand in 2020, says the contention fishing is a greater threat to dolphins than toxoplasmosis is “not backed up by any science”.
However, a 2019 paper, which Slooten contributed to, said: “For almost half a century, bycatch has been recognised as the most widespread threat to populations of small cetaceans.”
Meanwhile, in 2017 the International Whaling Commission said given the critical status of Māui dolphins “the highest-priority management recommendation is to eliminate bycatch”.
Helson is right DoC has found toxoplasmosis infection rates were high among dolphins, at 60 percent – of just 28 carcasses.
The idea toxoplasmosis is a “major threat” isn’t reflected in DoC’s draft toxoplasmosis science plan. While post-mortem findings suggest a high prevalence of the disease, “questions remain over how representative this is of the wider dolphin population”, the report says.
“With new fisheries restrictions, by-caught animals are increasingly less likely ... meaning that there will continue to be uncertainty around the disease in these animals.”
Helson pointed to a 2019 study by NIWA marine scientist Dr Jim Roberts, involving Massey University Professor Wendi Roe, which said toxoplasmosis was the main “non-fishery” cause of death in Hector’s and Māui dolphins.
While acknowledging fishery deaths are “more precise”, Roberts extrapolated the nine confirmed deaths to suggest there could be “hundreds each year”, “much greater than commercial fishery deaths”.
Conveniently, and unbidden, Seafood NZ provided emailed comments yesterday from Roberts and Roe.
Roberts said the threat from toxoplasmosis is “uncertain”, but claimed it was “almost certainly” greater than the threat from “entanglements in commercial fishing nets” – especially since new fishing area restrictions were introduced.
Roe said at least two Māui dolphins have died from toxoplasmosis, which “could be the tip of the iceberg”.
MPI “have been most vocal in pushing us to ‘do something’ about toxo” – internal DoC email
The fishing industry has been vocal about the disease. It put out a press statement in 2019, welcoming Roberts’ study.
In 2020, the annual report of NZX-listed fishing giant Sanford (now 19.9 percent-owned by Ngāi Tahu) said “we believe the science shows the disease is a more severe threat to dolphins than responsible fishing”.
The tension between fishing and disease threats is felt within DoC, internal emails reveal.
A staffer in the marine species team said MPI “have been most vocal in pushing us to ‘do something’ about toxo, to offset the pressure they have faced historically (and in some cases, currently) about the threat of fishing to the dolphins”.
That it was a “hot topic” was an “understatement”.
Newsroom asked MPI why it was worried about pressure related to the “threat of fishing to the dolphins”, but the response didn’t address that directly.
Emma Taylor, director of fisheries management at MPI unit Fisheries New Zealand said via email it worked closely with DoC to implement and monitor the Hector’s and Māui dolphin threat management plan.
“We have taken comprehensive steps to protect Maui and Hector’s dolphins from fishing-related threats,” she said. “Last year the Government announced that up to 300 inshore fishing vessels will be fitted with cameras by the end of 2024.”
It’s worth highlighting one last email exchange, again from last November.
Heeg, DoC’s aquatic director, responds to a push for DoC to lead on cat control by citing DoC’s legal responsibilities, and budget constraints.
“Our statutory requirements in this space are to control feral cats on PCL [public conservation land], which is being done, and to do science and research on the threats to marine mammals, and to manage those threats where it is in our remit to do so.
“Where some of those threats relate to other agencies responsibilities, like regional councils and others, we can inform and advise them, but we can’t take over their responsibilities.”
Van Helden, the marine species science advisor, says it feels disingenuous to say DoC is managing cats on conservation land.
“It is not being done at a scale that is beneficial to the dolphins. It is also possible that we could put our hand up to do a number of things with feral cats on PCL land, such as a serious programme to genotype these populations particularly within catchments that flow to Māui dolphin habitat, and this is not being done.”
With refreshing honesty, Van Helden suggests the department admit, if it’s true, that it’s struggling with the possibility of managing cats, hampered by overlapping responsibilities with other agencies.
“We should put our hand up and say this is to costly, too complex, and at too big a scale for us to manage – then at least other agencies can be aware of our limitations, and offer support, or encourage researchers to develop tools that can advance our cause.”
If the Government is serious about tackling cats, and preventing the spread of a disease known to kill endangered dolphins, then it may have to pick a lead agency from the line-up of reluctant candidates through new legislation. If it needs more money, perhaps it could ask The Morgan Foundation.
* This story has been corrected to say Jeremy Helson joined Seafood NZ from Fisheries Inshore New Zealand, not MPI
