Aquatic pests ‘pose threat to waterways

Holidaymakers may be unwittingly transferring invasive weeds and pests from one waterway to another, a scientist warned yesterday.

The National Aquatic Pest Awareness group has launched a campaign to remind people of the dangers 'aquatic hitch-hikers', such as algae, pose to many of New Zealand's unspoiled lakes and rivers.

The group, formed from Government and industry groups, has said water sports and fishing gear can carry pests from contaminated areas to other untouched sites.

John Clayton, science leader of the National Institute of Water and Atmospheric Research's aquatic plants programme, says almost all North Island waterways already have one or more pest, and the South Island will suffer the same fate unless the threat of aquatic pests is taken seriously.

"One of the things that makes New Zealand unique is the beauty of our lakes and rivers, and New Zealanders have great empathy for waterways, but they are being degraded," he said.

Dr Clayton said the group hoped to prioritise water bodies in relation to the risk they faced from pests and allocate efforts accordingly.

"To do this, it has been necessary to build up a picture of the state of all the water bodies around the country, understand what species are pests and determine the factors that heighten risk of pest transfer," he said.

"If a lake is already highly pest-ridden, as bad as it's going to get, there may not be much point trying to protect it, whereas there may be a water body close by worth protecting."

The Foundation for Research, Science and Technology has invested more than $2.5 million over three years in Niwa's research programme.

The group plans to produce guidelines by the end of next year to advise groups on strategies they should use to minimise pest risk.

Community and environmental groups, iwi, councils and the Conservation Department will be targeted.

"In the meantime, the public can help protect waterways by appreciating how easily aquatic pests can be transferred from one water body to another and taking action to prevent this," Dr Clayton said.

"Waders, fishing nets and lines are all potential sources of contamination.

"The discovery of algae (Didymosphenia) in the Waiau River that flows out of Lake Manapouri - probably the first time the algae has been found in the Southern Hemisphere - is thought to have been introduced on a tourist's fishing waders, as the area is only accessible by foot.

"Many of the weeds that are a problem in New Zealand reproduce vegetatively rather than from seeds, which means it only takes one small fragment to infest a whole lake," he said.

One example is hornwort, which has spread from the Waikato region to the tip of Northland and to the bottom of the North Island.

"Researchers have also found that hornwort displaces other native water plants, and it can have a negative effect on water quality and other aquatic life such as native fish.

"It is really important that the public remove all plant material from their boats, trailers, propellers, anchors, fishing gear and nets and jet skis before leaving a waterway."

- NZPA