Introduction

A new fish pass has been created at Pukepuke Lagoon with help from local contractors.

Date:  16 April 2009

When the Department of Conservation (DOC) embarked on a quest to develop adequate passage for native fish species at Pukepuke lagoon, a local Levin company, Higgins Contractors Ltd, stepped up to the plate providing man and machine to help with construction.

“Higgins has a long history of working in the area and has always had strong community support values, so when DOC approached us last year to provide costing for manpower, machinery and materials to build a fish pass at Pukepuke, we took the opportunity to support the project and help protect biodiversity in the area”, says Higgins Levin manager Owen Bonis.

Pukepuke Lagoon is a dune lake and wetland area managed by DOC, located about 3 kilometres inland between Himatangi and Tangimoana. It is home to many native species, including birds like the nationally threatened New Zealand dabchick (also known as weweia) and the North Island fernbird (matata). However the species that will benefit most from the new fish pass are long and short finned eel, and native fish such as giant kokopu, bullies and inanga, commonly known as whitebait, the “little battlers” of the fish world.

DOC rangers Lorraine Cook and Logan Brown happy with the finished fish pass.
DOC rangers Lorraine Cook and Logan Brown
happy with the finished fish pass

Whitebait need to overcome several obstacles when they travel from the sea each spring. Firstly they need to get past the whitebait nets near the mouth of the river. Those that miss the nets then need to be able to travel up stream unimpeded to find good quality habitat to mature. “Native fish can manage to wriggle their way through most natural blockages” says Lorraine Cook, Biodiversity Ranger for DOC, “but dams or weirs are usually a dead end”. Adult fish make their way back downstream in autumn to spawn in wetlands, estuaries and stream edges. “Sometimes the ideal habitat for the fish to spawn may be trampled and polluted by stock, which is one of the reasons why we advocate for streams to be fenced off” says Ms Cook.  The new fish pass will enable the whitebait species to travel further upstream in spring, and downstream to spawn in autumn regardless of water levels.

The other species benefiting from the fish pass are the eels which migrate all the way from Tonga as youngsters, travel up rivers, streams and wetlands where they usually live for more than 30 years. Only then do they migrate back to Tonga to spawn and die.

Water levels in the lagoon are controlled by a wooden weir. Fish ladders installed almost a decade ago did not allow sufficient passage for fish during dry months so DOC endeavoured to create a more effective fish pass. The new construction was designed to resemble natural streambed formations and allow adequate passage for native fish species in high and low water flow.

Higgins using machine power to spread metal.
Local contracter Higgins spreading metal
to create the fish pass

The fish pass is essentially a rock ramp, comprised of large rocks at the base with smaller rocks creating the slope and fine gravel to fill in the gaps.  Higgins Levin delivered rocks and gravels to the site. They generously provided labour and machinery free of charge to help with construction.

DOC is grateful for the assistance provided by Higgins Levin, and admits it came as a bit of a surprise. “We approached them for a quote and they came back with a really unexpected offer. To be honest, it would have been a real struggle to get the resources needed to construct the fish pass without the generosity of Higgins Levin”, says Ms Cook.

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Contact

Margaret Metcalfe
mmetcalfe@doc.govt.nz

Manawatu Base
Phone:   +64 6 350 9700
Fax:   +64 4 471 1117
Email:   manawatu@doc.govt.nz
Address:   717 Tremaine Avenue
Palmerston North 4414
Postal Address:   Private Bag 11010
Palmerston North 4442
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