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Yachties push for carp to control Quarry Lake weed

Flagstaff Team

Fish plan… North Shore Radio Yacht Squadron commodore Graham Cross (above), who wants non-invasive carp (below) introduced to Quarry Lake (top)

Radio-controlled yacht enthusiasts want carp introduced into Quarry Lake to control the weeds that are choking their Takapuna racing venue.

But it’s not a case of a pest fish being brought in to feed on pest weeds, says the commodore of the North Shore Radio Yacht Squadron, Graham Cross. Rather a limited number of “desexed” grass carp would be let loose – not more of the noxious koi variety already present in the lake.

Cross put his case to the Devonport-Takapuna Local Board’s community forum last month, outlining the issues faced by his club’s 45 sailors, and the canoe polo players who also use Quarry Lake. Floating weed routinely interrupted racing, causing delays and cancellations, he said.

The self-contained lake, accessed off Northcote Rd, was one of only a few good venues in Auckland used for the yacht racing. Local club members, raced there twice a week year-round. School Waterwise groups also used the venue, said Cross.

He said multiple approaches had been made to Auckland Council for more regular weed clearing.

Floating weed accumulated along the lake edges, including at the western end where the North Shore Canoe Polo Club launched canoes, said Cross. It grew in central areas where it tangled around the keels of yachts. “The moment that happens the race is over,” he said.

Weed also attached to course markers and to the polo club’s suspended lines. It backed up along booms put up to section off areas of the lake.

Club members had to row out in dinghiesto rake up and remove the weed. This had been going on for 20 years. The weed was then piled up ashore, becoming smelly, until the council collected it.

Cross said club members were good caretakers of the lake and its surrounds, regularly removing debris, but they were crying out for help and wanted the board’s support. The national bodies for radio yachts and canoe polo backed their call, he said. “They would love to see us run events, but we simply can’t because of the weed problem.”

Cross said the council had used a weed-cutting machine on a barge to cut weeds to a level around 80cm below water twice a year, but this had been reduced to annually. The last time this was done was in January, at a cost of around $19,000, but by Easter the club was again pulling weeds out – “about three boatloads”. Cross said this was not a sustainable situation.

Speaking alongside Cross was Peter Willcox, northern regional manager of the Aquatic Weed Management company. He assured the board using grass carp to keep weeds in check was not new, with the council having approved this in other places, including at Auckland Botanic Gardens. His recommendation was for 10 to be introduced to Quarry Lake.

Willcox said part of the work the company already did under contract to the council was managing pest fish and also checking water quality.

The herbivore carp grew to one-metre long, weighed 10-15kg and had a lifespan of 10 to 25 years. They were timid, likely to head to the bottom of the lake if disturbed, and did not bite.

Members received the club’s report and asked for it to be sent to the council’s Infrastructure and Environmental Services section to come back with feedback on next steps.

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