Giant 18-inch whitebait stuns west coast fisherman

A fisherman was surprised to discover that he had caught a giant adult minnow on the west coast that was estimated to be up to 40 years old.

Tyler Glover said he caught the “beautiful” giant kōkopu on the shores of a west coast lake on Sunday.

“I was incredibly surprised and I didn’t quite realize what the fish was at the time,” he said.

He took a photo before releasing the fish back into the lake.

READ MORE:
* Top DOC staffer criticized for coarse fishing at river proposed for fishery closure
* Investigating the influence of minnows on fish size and reproduction
* Whitefish season could be closed earlier to help accommodate declining numbers
* Activists claim that a fishing ban could save whitefish from extinction

He uploaded the photo to Facebook, where it was identified as a giant kōkopu – a fully grown adult whitebait classified as endangered.

Glover said he caught the fish, which he estimated to be about 18 inches (45 cm) in length, around 12:30 p.m. Sunday.

“[It was] so wonderful and special to know that I got to witness such a beautiful fish. I can’t imagine many fishermen getting the chance,” he said.

Fellow anglers reacted to the photo on the Trout Fishing New Zealand page with some surprised to see adult whitebait getting so big.

‘That’s the biggest Kōkopu I’ve ever seen! Well done for putting it out, not many these days,” someone said.

“Great once in a lifetime experience, thank you for catching and releasing, it’s a miracle. None of us have ever seen it [or] ever see,” said another.

Niwa freshwater ecologist Mike Hickford estimated the fish to be 30 to 40 years old.

“It’s a beautiful fish in beautiful condition,” he said.

The scientific name is galaxias argenteus because the markings look like a galaxy in the night sky, he said.

The giant kōkopu is the largest whitebait, constituting about 1% of the population.

Hickford said the adults are nocturnal and are mostly found in coastal wetlands but can travel to lakes where they eat invertebrates from the bottom.

“There is no evidence that the larger kōkopu were ever used as a food source. It would taste a bit like mud,” Hickford said.

The adult giant kōkopu spawns several times during their lifetime, and the offspring travel to the ocean before returning to rivers as juveniles.

Whitebait fisheries target the returning juveniles that travel upstream in schools before finding a place to spawn in the riverbanks. On the west coast you can fish for coarse fish between September 1 and October 30.

Hickford said some people speculated whitebait was swimming up rivers later this year because of the heat wave at sea in which the sea temperature was six degrees higher than normal.

“I have no data, no one has. People suspected it was a little different this year, but we would expect whitebait to get into the rivers all year round.

“The reason we have a season is to provide protection for some of the whitefish that come in.”

The most common species was the inanga, which dispersed over great distances at sea, but only lived for a year.

Hickford said two of his PhD students from the University of Canterbury, Ben Crichton and Andrew Watson, had studied the consequences of closing rivers for whitefish fishing.

Unsurprisingly, the study found that more young people could get upstream if there was no fishing on the river.

However, Watson found that the more inanga there were in closed rivers, the smaller they became and the fewer eggs they produced due to the greater number of fish competing for food.

“So the effect on population is not that big for inanga,” Hickford said.

Crichton looked at banded kōkopu and found that closing the river had no effect whatsoever on the number or size of the fish, as the juveniles were eaten by the increased adult population.

“The research is ongoing, but the main message so far is that having a healthy habitat has more impact on the final numbers than having a whitefish fishery,” Hickford said.