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Big Boost for Lake Arapuni Trout Numbers

Friday 12 August 2011, 9:16AM

By Fish and Game NZ

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WAIKATO

Good news for Waikato anglers – Fish & Game has taken another step towards trebling the number of trout being released into Lake Arapuni – the district’s most popular sport fishing lake.

The latest release of 2000 one year-old rainbow trout trucked from Fish & Game’s hatchery at Ngongotaha near Rotorua, was carried out this week (10/8/2011).

Auckland / Waikato Region Fisheries Manager Ben Wilson says releases have been increased from 2,000 to 6,000 rainbow trout. However they have been spread over six months to avoid a “growth bottleneck” that’s occurred in previous years when the fish were released in a single annual liberation.

“We’ve been able to step up the number of fish released thanks to funding from the Waikato Catchment Ecological Enhancement Trust, ” he says. The trust is funded by Mighty River Power to enhance the Waikato River catchment’s sports fisheries and habitat.

The lake is the most popular of Waikato’s hydro lakes for trout fishing with a reputation for good catches of both large rainbow and brown trout. Fish & Game keeps it stocked with trout because there are limited spawning opportunities.

Arapuni has been productive over recent weeks for shore-based anglers in the upper reaches at the Waipapa Dam, while boat anglers have also done well, Ben says. Anglers have been catching plenty of wild rainbows, averaging about 50 to 55cm and in good condition, while the hatchery-reared fish released last year are thriving. Fish that were liberated in May are 48-50cm, and those released in October are measuring 43 to 45cm.

Ben Wilson says large numbers of wild brown trout now make up about 20% of the total catch and they are nearly all a healthy 57 to 63 cm in size – which suggests they are from the same year-class, presumably all born in 2008. “Brown trout can live up to six years in Arapuni, around two years longer than rainbows – so some of these trout will reach 70cm-plus.”

Some of the hatchery fish are tagged so that growth rates can be monitored – 500 of the latest fish released this week were tagged.

“We’d be pleased if anglers who catch a tagged fish can report the details to Fish & Game. It is crucial information for us in accurately monitoring the state of the fishery,”says Ben.