Boaties asked to watch weed

By ROSALEEN MacBRAYNE

Boaties are being urged to help prevent the spread of exotic weed and fish pests in the scenic central North Island lakes that are plagued by toxic algae.

As the October 1 opening of the trout fishing season nears Environment Bay of Plenty is warning people to wash down their boats carefully before taking them into new lakes or rivers in the region.

It was of absolute importance to check boats, trailers, jet units and anchor chains, said council officers concerned about the ease with which aquatic weed can be transferred from one lake to another.

Pest plant co-ordinator John Mather said some Rotorua lakes were free of the more invasive exotic submerged macrophytes, or oxygen weeds. Lake Rotomahana, for example, did not have any weeds of that type, while Lake Rotoma had only one of a range of species.

"Yet that can change very quickly," he said. "All it takes is one boat to bring it in."

Mr Mather said some of the lakes now hosted tall underwater forests of exotic weeds that had taken over from native plant life.

"We don't want these weeds to spread even further - and boaties have a part to play in that," he said.

Environment BOP pest animalco-ordinator David Moore said diligent boat owners had helped to keep Rotorua's lakes free of the environmentally harmful koi carp. But it was all too easy for eggs or small fish to hide in strands of lake weed.

Lake Taupo and lakes in the Waikato hosted koi carp and "we don't want them here", he said.

"It is critical that everyone continues to check for pest fish. We can't afford to get complacent."

Koi carp degrade water quality and are a serious threat to native marine life. Possessing or rearing them could bring a fine of up to $5000.