Lake Wainamu water quality improving

11 August 2005

The freshwater lake at Te Henga (Bethells Beach) is experiencing its highest water clarity in 17 years.

The improvement in clarity and increase in native fish numbers at Lake Wainamu follows an Auckland Regional Council programme to net exotic fish.

Auckland Regional Council staff carried out the netting programme with help from the local community. More than 10 kilometres of net were set, resulting in the removal of 2800 fish. A number of the fish were fed to animals at Auckland Zoo.

The results of the netting programme were reported to the council’s Parks and Heritage Committee meeting today.

Auckland Regional Council Environmental Science Project Leader Grant Barnes says independent research by NIWA has confirmed the fishing was a big factor in improving the clarity.

“Tests have found some of the best water clarity since regular monitoring began in 1988.

“Before the netting programme water clarity in the lake was less then two metres and we found occasional blooms of blue-green algae.”

Mr Barnes says the improvement in clarity has been helped by the return of aquatic plants to the lake.

“The fishing has hastened the return of aquatic plants.”

Lake Wainamu is a freshwater lake accessed from the sand-dunes at Te Henga (Bethells Beach). It is a popular spot for swimming and picnicking.

Water clarity in the lake has reduced during the last 15 years and the number of native fish has been falling.

The intensive netting programme was carried out during April and September 2004 and February this year.

Mr Barnes says netting reduced the numbers of exotic fish, in particular perch, goldfish and rudd.

“Because larger predatory fish are now at very low numbers the opportunity for native fish to recover is significantly enhanced.”

“We need to continue netting to maintain low fish populations, but the level required will be significantly lower than this year,” says Mr Barnes.

The next netting programme will begin on 22 August, he says.

ENDS

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