RAIN SHEETS in waves. Cats-and-dogs rain. Coast rain. The view from the Mahitahi River bridge isn’t very inspiring on this damp day. Neither is the concrete span itself, a purely functional structure—like much New Zealand engineering of its era. The workers who built it in the 1940s reported seeing large shoals of grayling—or upokororo, as Maori called them—in the river. They reputedly ate some, too—captured with explosives. But is this story just West Coast folklore? Or does a remnant population of upokororo hold out in some isolated stream?
Reports of grayling over the past 70 years are based not on hard evidence but on a human weakness for a belief in the improbable. However, it was a belief in the improbable that turned up the takahe and kakapo and possibly the moose. If New Zealand’s bush has hidden the lost, what of its waterways? Do they harbour a mystery fish?

In freshwater fisheries circles the grayling is a rather mystical species. For much of the last century it remained elusive, just around the next river bend. At Otago Museum, collections and research manager Brian Patrick shows me the two specimens it holds. They are each about the size of a small trout. The first is a wrinkled, dull-brown, stuffed creature: “Molyneux (Clutha) River 1874,” reads the index card. The other, taken from the Waitati River, north of Dunedin, by one F. Smith in 1912, is preserved in a bottle of formol. Brian thinks it “is actually a juvenile salmon”. It certainly doesn’t resemble its mummified partner.

Although time has not been kind to these specimens, reports have the grayling as a beautiful fish. In 1885, William Arthur described it to the Otago Institute as “slaty-brown along the back passing into slate-blue on sides and silvery-white on belly, which had patches of azure, no spots… Fins orange colour tipped with dark slate and white; cheeks with a golden tinge.” In 1889 West Coaster F.E. Clarke referred to a Hokitika River catch as “the White Spotted Grayling”, suggesting variations in colour occurred. And in 1916 D.H. Graham caught specimens “brightly coloured, almost a warm orange” from the Otara River near Opotiki.

Vagaries and suppositions are the grayling’s legacy. Perhaps the only certainty was its abundance. Its plenitude was such that it was used on occasion as fertiliser on market gardens. During the winter months “cartloads” were at times taken from a tributary of the Wairau River, in Marlborough. In his 1903 Notes on New Zealand Whitebait, James Hector, a versatile government scientist, noted that “they assemble in streams in immense numbers”. And in 1869 a mill wheel on the Hutt River was brought to a standstill, the channel choked by thousands of the fish.

Grayling sustained Brunner on his 18-month expedition to the “middle of Middle Island”. On January 18, 1847, his guides took “fifty good-sized fish…called the upokororo, or fresh-water herring” from the Buller River using a kupanga, or net, 50 ft by 4 ft. A meal of cabbage-tree root and grayling “make a fine meal”. Four days later they had caught a total of 150 fish, which they salted and dried. Without grayling Brunner may well have perished.