Fishing tournaments increase aquatic weed risk
Fishing tournaments increase aquatic weed risk for Rotorua lakes
For immediate release: Thursday 13 May 2004
Rotorua’s boaties have been pretty quick to learn they must check boats for stray weeds after use. However, a series of major fishing tournaments this year will be a further test for the Rotorua lakes, says Environment Bay of Plenty’s pest plant coordinator John Mather.
Last summer, Environment Bay of Plenty and the Department of Conservation launched a major promotion to protect Rotorua’s lakes from new aquatic weeds and pest fish like koi carp. It reminded people to always clean their boats before bringing them into the district or transferring them between lakes.
Over Easter, a survey of 100 boaties revealed two-thirds had checked or cleaned their boats before launching them. Fifteen percent did not check their boats because they only ever used them in one lake. That meant 15% did not get checked and potentially posed a risk to the lake environment, Mr Mather says. “All it takes is for one boat to bring a new weed in,” he explains. “Some of the lakes already host tall underwater forests of exotic weeds, which have taken over from the native plant life. We don’t want that to keep on happening.”
However Mr Mather says awareness of the issue seems to be increasing. “It looks like the message is getting out there.” The two organisations will continue to promote it, especially during major tournaments like The Rotorua Tagged Trout Contest on May 15 and 16.
“It’s a risk whenever new people come to town,” he explains. “They may not realise the absolute importance of making sure they haven’t bought weeds in with them.”
Large banners promote the message at every entrance to Rotorua
Mr Mather says it is important to carefully inspect boats, including propellers and anchor chains, as well as trailers, before taking them into a new water-body. The eggs of pest fish like koi carp and catfish also hide in strands of weed. While lakes in the Waikato region have koi carp, Rotorua’s lakes are still free of them.
Koi carp were probably brought to New Zealand with stocks of goldfish. Wild stock is thought to have escaped from ponds. Koi carp degrade water quality and are a serious threat to native freshwater marine life. They grub for food from the bottom sediments of lakes and ponds, uprooting plants and stirring up the water, which reduces water quality.