Source: Radio New Zealand
A native freshwater fish thought to be lost from Auckland’s wetlands has resurfaced after more than a decade of searching.
Populations of the endangered Waikaka, or black mudfish, have been relocated in a small corner of Helensville in the last couple of months.
Auckland Council’s senior regional fresh water advisor, Matt Bloxham said the finds of the small eel-like critters in October were surprising.
“We’ve been looking since 2014, spreading the net as it were to other areas… mudfish have really specific requirements in terms of habitat so not every wetland is going to hold habitat useful to mudfish but finding them has proven harder than than we expected.
“It was this year that we found two new populations so it’s been quite an amazing year for us.”
He said the latest finds were located in a small body of water of only a few metres, the space likely created by roaming deer.
Bloxham said there’s a number of pressure points that have strained black mudfish numbers like introduced flora and pest fish, but the greatest threat is the loss of about 90 percent of our wetlands.
A black mudfish. Nick Monro
“Unfortunately you know, they are wholly reliant on on their habitat remaining good in order to make a living.
“Wetlands are slowly becoming modified by nutrients and sediment and the encroachment of the smothering vegetation.”
Black mudfish populations have been reduced to pockets in between Waikato and Northland, he said.
The precarious nature of their existence is such, that Bloxham said the small strip of water they were found just weeks ago had now mostly evaporated.
Auckland Zoo ectotherm keeper, Julie Underwood said the native fish would’ve since secreted themselves into the mud, lying dormant.
“They have abilities like surviving out of water so they don’t have scales they have leathery skin with a mucus layer and they can actually absorb oxygen through that as long as they’re damp.
“So when the wetland dries out they can hunker into the mud and kind of survive that dry period when all the other fish have to leave the area so it’s a good survival technique.”
Where the mudfish were discovered. Nick Monro
Underwood had been part of Auckland Zoo’s breeding programme which started in 2015 after black mudfish (Neochanna diversus) were brought to them from mana whenua in Hikurangi, Northland.
The zoo had been working in collaboration with local iwi and a collective of hapū kaitiaki from the North Island, Ngā Kaitiaki o Ngā Wai Māori.
She said the work had been a success.
“So we’re 350 fish later and we’ve run out of room so we’ve actually stopped active breeding and now we’re just sort of gearing up and looking for places to release them back to the wild.
“The idea was to basically create tiny wetlands a really naturalistic habitat step back and try and let the fish do their thing and then we more step in with looking after the eggs and raising the fry so that’s the trickier bit.
“For us luckily if we put the fish in together we generally get eggs but it’s kind of following that through and raising those fry to adulthood that’s a little bit more technical.”
Auckland Zoo ectotherm keeper, Julie Underwood. Nick Monro
Underwood said it was a good example of what could be done for conservation without needing to spend a whole lot of money or use a lot of technical equipment.
Auckland Zoo ectotherm team leader, Don McFarlane said the next step was now the greatest challenge, finding these native fish a suitable home away from pests and human influence.
He said partners like Ngā Kaitiaki o Ngā Wai Māori had been learning how to care for the fish at Auckland Zoo, with the aim to re-release the zoo’s Waikaka back to where they came from.
“What we’re looking for is, first and foremost, is the hapu from Hikurangi, Ngā Kaitiaki o Ngā Wai Māori, choose that site and that it’s a site that is in their rohe and a site that they can protect and have guardianship over.
“Because the site needs to be protected, but not just a few months or a few years, but in perpetuity. That’s quite an ask.
“We are struggling with council and our hapū friends in Hikurangi to find a suitable place to put them.
“And that tells you everything about the state of the wetlands in New Zealand. We’re a little bit restricted further because we want them to go back from whence they came.”
The wetlands where the mudfish live are diminishing. Nick Monro
McFarlane said New Zealand’s wetlands were diminishing despite their importance ecologically.
“Where on earth do we find a pristine wetland that we can protect, that has oversight long term to protect? It’s less than 10 percent of wetlands left. In that is the answer to our problem. We’ve got to protect what’s left, basically and that’s with government.”
“We may have to consider, like many other international conservation organisations are starting to look at, sites that are still protected that are actually not from where the animal originally came from, simply because you have no choice.”
“They can’t live in zoo situations or captive situations forever.”
He said one of the greatest tragedies in the story of New Zealand’s black mudfish, is the fact they were once one of our most abundant fish.
The area in Helensville where they were found. Nick Monro
“They were a source of food for Māori once, so there’s a cultural heritage loss here as well, which is undervalued and underappreciated.”
“There’s deep cultural associations with this fish for many Māori, many Iwi, and it’s disappearing. How do you value these things? It is very difficult. Uniqueness is important, I think it’s fair to say, and it is fast disappearing.”
“The world is becoming a very bland place when diversity is lost, and the thing is they are the canary in the mine for the habitats in which they’re associated.”
The discoveries were fantastic, McFarlane said, but it was a reminder of the habitats they were reduced to existing in.
“We must do what we can to take action to save what’s left,” he said.
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– Published by EveningReport.nz and AsiaPacificReport.nz, see: MIL OSI in partnership with Radio New Zealand