Trout stranded as Waitaki River drops

Falling water levels in a North Otago river have left trout high and dry, much to the concern of Fish and Game New Zealand (FGNZ) and local farmers.

Farmers Melany and Craig Hawkins, of Kurow, 68km northwest of Oamaru, yesterday found trout dying in pools of water isolated from the Waitaki River's main flow and alerted FGNZ.

FGNZ central South Island officer Graeme Hughes said the river's flow at Kurow was about 150 cubic metres per second (cumecs), and 160 cumecs nearer the coastline.

He rescued some fish, but said it would be an uphill battle with countless other ponds along a 70km stretch of river bed.

Without the right equipment rescuers would struggle to release fish back into the river, he said.

Meridian Energy spokesman Alan Seay said the company had dropped the level of the river with approval from FGNZ.

Staff from both organisations were monitoring the situation.

Mr Seay would not speculate whether the river flow would be further reduced under the company's project aqua hydro-irrigation development.

The low river level related to movement of water between storage lakes in response to the current below-average lake levels, he said.

Fish trapped in the pools would be aware of their predicament and know they were being exposed to the air, Mr Hughes said.

He had heard from other people who had seen trout spawning with their backs out of the water.

Most of the redds (egg clusters) were wetted and ova would survive if the temperatures were cool, he said.

But the hatchlings would need water flow to provide extra oxygen for survival.

The pools also caused dehydration of indigenous species that were not valued for fishing but were a food source for the larger fish and part of the ecosystem, Mr Hughes said.

- OAMARU MAIL