MEDIA RELEASE
Horizons Regional Council

Monday 22 April, 2013

Pest fish monitoring a step forward for lake restoration

The completion of pest fish monitoring on Lake Horowhenua last week marks a step forward for lake restoration hopes.

With the permission of Lake Horowhenua Trustees and Lake Domain Board, Horizons Regional Council engaged the services of Waikato University to undertake a monitoring programme to establish the level of pest fish populations and inform options to manage these. Controlling pest fish populations is a potential management tool to contribute to improving lake water quality and reducing toxic algal blooms.

Waikato University scientist Grant Tempero reported his findings to Lake Horowhenua Trustees, Lake Domain Board members, Horowhenua District Council and Horizons staff at a meeting on Friday.

“We have been fishing for four days and are very happy with how things have gone,” says Mr Tempero.

“In terms of pest fish we found large perch fish but not a high population, there are also goldfish and a few carp but these are again at low numbers. As for other fish we caught 1,796 eels in our nets, there is a good population of native bully and even some whitebait.

“The average eel size was relatively small but the numbers are high so in five to ten years time they could easily grow to a healthy fishery.

“At this stage I’d say the future of the lake looks promising if you were to judge it by the fish ecological system. We’ve observed there is plenty of food and so still a lot of hope for the fish population,” he says.

Horizons freshwater and science manager Dr Jon Roygard says while there are some challenges for recreational use of the lake in terms of water quality, the monitoring results demonstrate the fish population is well placed for lake restoration.

“Goldfish and perch are known to have negative impacts on water quality in some places so knowing they are at a low level is promising,” he says.

“The research also shows whitebait and mullet are present in low numbers which indicates there would be real value in installing a fish pass at the lake weir to enable them to move freely between the lake and the sea to complete their lifecycle.”

Lake Trustee Dr Jonathan Procter says the group is ecstatic to learn there are still so many eels in the lake.

“We think it’s great to have this information now. There’s still a big job to do going forward to maintain good fish numbers and reduce pest fish but this information will be crucial for lake restoration,” says Dr Procter.

The monitoring results will be written into a report that will help lake restoration partners determine what needs to be done in the future.

“Horizons plan to install a flow recording site, lake monitoring buoy and a lake level monitoring site within the next two months to provide important information on the health of the lake and data to assist with its restoration. This is all part of a work programme that lake restoration partners have agreed on and initiated, beginning with pest fish monitoring,” says Dr Roygard.

“Beyond monitoring we are also undertaking further stream fencing and planting around the lake and its tributaries.”

Horizons chief executive Michael McCartney says the information provided by pest fish monitoring will be crucial to show the progress made over the years ahead.

“This monitoring marks the beginning of a journey to bring the mana back to the lake and as the regional council we are committed to seeing it returned to its glory,” says Mr McCartney.

Horowhenua District Council mayor Brendan Duffy says the independent research conducted by a nationally recognised and respected institution negates any opportunity to question the results.

“From the information presented we are in an extraordinarily positive position and it shows the establishment of a partnership between interested parties is absolutely the right decision. It will allow us to collectively develop a plan of action, seek funding and deliver lake improvements,” he says.

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