In search of Mudfish

Forest and Bird, Issue 279, 1 February 1996, Page 14

In search of

Mudfish

DAVID YOUNG

Sometimes known as mud eel or spring eel, mudfish are one of the strangest and most secretive of New Zealand's native fish.

looks at what is known of the

animal Maori call hauhau or waikaka.

IG DEEP enough into the mud of old forests on the West Coast and you may come across a peculiar, elusive, tenacious fish that seems more a product of Hollywood than New Zealand. This is the mysterious brown mudfish (Neochanna apoda). Endemic to this country, it can live deep in soil without water for long periods of time and can survive deforestation, drought and probably burn-offs. Though in every anatomical sense a fish, it is quite amphibious in the way it is adapted to dwelling in ephemeral forest ponds and wet places, like pakihi swamps and damp paddocks. The mudfish delighted toiling settlers during the 1860s — the period of the New Zealand Wars. They discovered that their swampy potato patches yielded not only spuds, but fish: or "fish and chips" as fisheries scientist Dr Bob McDowall could not resist noting in his book, New Zealand Freshwater Fisheries. As well as the West Coast, the brown mudfish is also known from the west coast of the North Island, in particular the

Whanganui, Rangitikei and Manawatu catchments, as well as in the Wairarapa. Dean Caskey and Matt Cook, from the Department of Conservation’s Stratford field centre, returned to previously known haunts of the animal in winter 1994 to discover that in some places they were still there. When the fish is found it is often in plentiful supply. In Ngaere, formerly a 4,000-hectare swamp whose remnant today is a mere ten hectares, they found 57 mudfish from three nights’ fishing. "A lot of farmers came back to us after we advertised," says Wayne Hutchinson, senior DoC conservation officer at Wanganui. "The fish turn up if they have been digging drains. So a lot of their habitat is quite terminal". The new findings of the brown mudfish — and its close relatives the Canterbury mudfish and black mudfish — raise some important issues. As Gavin Smith, planner for DoC’s West Coast conservancy puts it, the fish’s presence is a reminder that even in cut-over landscape, be it pakihi or even in old mining towns such as Kumara, there are natural ecosystems at work. "It can be found under houses (as it

was in Kumara), in paddocks, floodpools and pakahi. We have a responsibility under the Resource Management Act to protect these species — even when they occur outside national parks and protected areas. "Tt illustrates the large unknowns in so much of the work that we do," says Smith. "Tt’s listed as a class B threatened species, but it’s quite possibly widespread over the West Coast. "The fish is affected by land use as much as what happens to waterways. It is a species that could be lost or dangerously depleted before we really knew we had it." ISHERIES RESEARCH technician E::.; Eldon, now retired, agrees: "They are so bloody cryptic, people don’t even know they’re there." He described how, years ago, he visited Karamea, only to be assured by local bushmen that mudfish did not exist there. "There were a number of puddles out in the bush and we went there and fished them up from right under their feet." Eldon said that the mudfish had been reported only once this century in

Taranaki. "But when DoC got interested and set out to look for them, they found them all over the place." No one is sure exactly how widespread or densely distributed these animals are, either on the Coast or elsewhere, "We think they may be present in any places where there are old glacial or marine terraces, says Smith. "They can burrow down at least a metre into the ground. They have also been found in dune swamps. In one area where they were known to exist, 15 were trapped in a single night." DoC fish scientist Campbell Robertson says that vegemite makes a most attractive lure but they also "eat anything that moves and are most aggressive". Brown mudfish are most easily discovered in winter, and they have not been found more than 200 metres above sea level. Apart from their appearance in the most unlikely places, the mudfish also occur where they might be expected, in places like the whitebait spawning area in the important Kongahu Swamp, south of Karamea — a wetland so acidic it is impossible to do electric fishing there. While, says Smith, most of the dam-

® mudfish

age to mudfish habitat on the Coast has already been done, wetland drainage is still permitted by the transitional regional plan. The proposed regional policy statement supports the idea of protection and a series of fish and wildlife surveys are being conducted on the Coast. "The brown mudfish seems to live where few other fish do, and so we find that the only other creatures in its habitat are eels and koura." Peo Ge | ee cure mudfish species attracted some interest last century, it was PRE FEOL S

Tony Eldon, inspired by Bob McDowall, who was responsible for the revival of interest in the 1960s. He found it to be abundant in forest swamps and bogs, mostly in shallow water of less than half a metre. Frequently, it appeared in holes round the buttresses of trees. He also noted that it was highly nocturnal. It is the mudfish’s tendency to "aestivate" (rather to fish what hibernating is to bears) in mud in a state of torpor, that still interests those who find them. More

than 100 years ago R.C. Reid wrote, "As the water dries up it is forced to wriggle into the mud ... it has been known to follow down the moisture in holes left by decaying roots and get a considerable depth underground ... the discovery of a healthy fish five or six feet under solid dry ground has been looked upon as truly miraculous." But as they are not totally inactive, McDowall questions whether they truly aestivate. Eldon suggests that some members of the same galaxiid family have already evolved a capacity for breathing air which has enabled the mudfish to survive without water. This is what some juvenile fish are capable of as they pass up the edges of waterfalls. From this it was a short step to adapt to an earthy habitat where there was little competition from other fish. Apart from the importance of this little-understood creature and the habitats in which it can flourish, brown mudfish are almost certainly an important bio-indicator. "They are never found in foul water, they are only in good clean oxygenated water," says Eldon. Seventy years ago W.J. Phillipps reflected ruefully on the future of the mudfish: "As the forest is gradually being cleared and the swamps drained there is little doubt that yet another animal unique in the natural world of New Zealand will 4 become extinct." % Today the conservation status of the

brown mudfish is still precarious. It presents New Zealand, once again, with the case of a natural phenomenon that belongs to these islands only: a reminder of the unique features of this ancient Gondwana relic for which we are all custodians. Like its forest companion, the kahikatea, the mudfish can only benefit from closer scrutiny and the possibility of greater protection. @

Davip YOUNG 1s a freelance writer based in Wellington.