Native Fishes of the Whanganui

A native grayling recently rediscovered in the collection, caught in the 19th century.

A native grayling recently rediscovered in the collection

New Zealand is famous for its extinct birds, but not many people know we have an extinct fish. The native grayling or upokororo (Prototroctes oxyrhynchus) was found in many rivers and streams, including the Whanganui basin. The size of a small trout, it was good eating and extensively fished by Māori and pākehā. By 1900 it was rare, and it disappeared in the 1920s.

Remarkably, we recently came across a native grayling in our collection. Some time in the 19th century it was skinned, stuffed with cotton wool, and mounted on a board (originally painted blue, from the traces of blue paint on the fish’s back). At nearly 30 cm long, it’s one of the largest specimens known.

It’s hard to imagine what the Whanganui River was like at the time that grayling was stuffed and mounted. The first pākehā settlers described the banks as steep and lined with piles of sunken logs. When this wood was dug out for building, the banks eroded back a chain (about 20 m) on both sides. A century ago, a newspaper accounts tells us, the Whanganui was clear enough for someone to find a wedding ring on the river bed that had been dropped from the town bridge; imagine trying to find anything dropped into the river today! There were numerous side streams, even in the middle of town, that have since been covered over and culverted.

The Giant kokopu (Galaxias argenteus)

The Giant kokopu (Galaxias argenteus)

The river and side streams would have teemed with native fishes. Not just eels, but īnanga (the main whitebait species) and many different kinds of kokopu. The largest was the giant kokopu, growing over 40 cm long and weighing up to 2 kg. We only know that giant kokopu lived here because the museum has one, preserved in alcohol, caught at Kaitoke in 1948. Who knows how much longer they hung on in the area before being wiped out by agriculture and overfishing?

The kokopu pool near Karaka Street

The kokopu pool near Karaka Street

Even today, you can still find native fishes in some of the remaining urban streams in Whanganui. Īnanga and eels live in the creek running behind Aramoho School, and rare freshwater mussels are still surviving in the Matarawa Stream that flows through Kowhai Park. The swampy wetland behind the houses in Karaka St drains into a small stream, which was originally created as a drainage ditch but turns out to have the largest population of banded kokopu (Galaxias fasciatus) we’ve yet found in the Whanganui area.

The banded kokopu (Galaxias fasciatus)

The banded kokopu (Galaxias fasciatus)

As part of River Week, local fish expert Stella McQueen and I ran a night-time fish-spotting expedition to Karaka Wetland. Most native fishes are nocturnal, so can only be caught with headlamps and nets. We caught, measured and photographed banded kokopu (some up to 24 cm) long and released them into the stream again, except for two, which are on display in our aquarium in the Museum atrium.

Raising awareness of native fishes is part of our job; these are taonga, some of them threatened or endangered, literally living in our backyards. They’re incredibly vulnerable: vandals, eel fishers, or someone thoughtlessly dumping a drum of paint thinner could wipe out a streamful of fishes that have hung on right through Māori and European settlement, from a time when the Whanganui and its streams only flowed through swamp and forest.

Dr Mike Dickison is Curator of Natural History at the Whanganui Regional Museum.

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