An “elusive” mudfish that is unusual for never leaving its wetlands environment has staged an expected comeback in a muddy pocket of Auckland.
Adults and juveniles of the regionally endangered species, also known as Waikaka, were recently found in a Helensville wetland during a joint Auckland Council/Watercare survey.
Auckland Council freshwater senior regional advisor Matt Bloxham said the council was “cautiously optimistic” about the discovery as the wetland was choked with invasive vegetation, reducing the area the fish could live in.
“But discovering nine fish, including juveniles, hiding in isolated, shaded, water-filled depressions show these fish are making a go of things and reproducing in these tiny pockets of wetland,” he said.
One of NZ’s most unusual species
What made the small, eel-like mudfish unique also made them vulnerable.
They thrived in shallow, secluded pools under the cover of native vegetation, feasting on falling insects.
A hardy fish, they could survive dryer summer months without water by slowing their metabolisms and burrowing into moist, muddy spots awaiting the return of rain. They absorbed oxygen through their skin.
“This gives them an advantage over would-be competitors. Juvenile eels that manage to reach these secluded, temporary pools are forced to leave before they grow large enough to predate resident mudfish,” Bloxham said.
While most of NZ’s freshwater species eventually made their way out to sea, mudfish spent their entire lifecycle in wetlands.
Wetland habitat loss or degradation could spell the end of entire populations.
Auckland had already lost 97% of its original freshwater wetland area.
“They’re quite muted, not flashy or colourful but they’re kind of cute,” Bloxham said.
A win for biodiversity
Further searches prompted by the initial discovery led to a second population being found within a month of the first.
Auckland Council general manager of environmental services Samantha Hill said rediscoveries such as this were vital wins for biodiversity.
“Each new population found, helps secure the species’ future in the region and guides how we manage and protect these special wetland habitats,” she said.
“What we hope to do in these instances is work closely with landowners to control invasive weeds and predators, restore wetland buffers, and where necessary, restore a wetland’s hydrology.”
Auckland Council began a mudfish protection programme in 2014, with the long-term goal of establishing “self-sustaining wild mudfish populations that can withstand regional threats like land-use change and drought.”
This has included working with Auckland Zoo on captive breeding and rewilding opportunities.
The search for more of the unpredictable fish will continue.
