More than 66,000 catfish have been caught in Rotorua lakes since 2016. Now the Lakes Water Quality Society wants to take drastic action to prevent further spread of pest fish and weeds. Journalist Zizi Sparks finds out what it means for boaties.
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Every person launching a boat into a Rotorua lake will have to prove it is clean if a proposed programme is adopted.
The Lakes Water Quality Society wants to see a clean boat certification programme introduced.
Society chairman Don Atkinson said the programme would require every boat owner to inspect their boat and certify it is clean through a phone app or a computer, before launching it.
The information would be fed to the Bay of Plenty Regional Council and compliance would be monitored on the water.
"Rules already require a check but the big issue is that rule has not been well understood," Atkinson said.
He said this would prevent the spread of lake weeds and pests like catfish.
"The introduction of catfish into the lakes is most likely through boat owners. We've got them now in Rotoiti and Rotorua and that increases the danger of spread to other lakes, but we want to make sure we don't make the same mistake.
"The other big issue is just over the hill in the Waikato they've got far worse weeds and pests than we have got here. With time it's inevitable we will get further introduced pests."
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About 66,000 catfish have been caught in Rotorua lakes since the first one was discovered in Lake Rotoiti in 2016.
Atkinson wants to see the programme included in the Bay of Plenty Regional Council's proposed Regional Pest Management Plan. The society made a submission opposing the plan in the hopes the addition could be made.
The proposed programme will be discussed at the Lakes Water Quality Society's 2019 Symposium on November 7 and 8 at the Millennium Hotel.
Atkinson said the symposium would also cover Rotoehu, the region's worst quality lake, and underlying water quality issues.
Iwi, council and Government representatives are expected to attend and it is also open to the public.
"By attending they demonstrate concern and support for our principal topics of preventing the further spread of catfish and weed, support restoration plans for Lake Tarawera and demand urgent action for the recovery of Lake Rotoehu."
Bay of Plenty Regional Council biosecurity manager Greg Corbett confirmed the council received a submission from the society, which asked for a requirement that "every boat entering any of the Rotorua Lakes be required to certify that the skipper has checked, flushed, drained and cleaned his boat, trailer and associated gear".
Corbett said in subsequent meetings, it was agreed that greater compliance with rules surrounding the cleaning of boats needed to be achieved.
Elected members will workshop the regional pest management plan by the end of this year, at which time the society's submission would be considered. Adoption of the plan would happen by mid-2020.
Corbett said this plan directed the council's response to pests, based on an assessment of the severity of the threat, the cost of action, and effectiveness of response.
Grant Wallace, a member of the Lake Rotoiti Classic and Wooden Boat Association, supported the proposed programme, as long as it was not hard to comply.
"I think we've got to move forward with some initiative to try control these pests spreading.
"It's not something new in the world. In the USA at places like Lake Tahoe, there is quite a regime for inspecting boats for these very reasons."
He supported the idea of using an app for certification.
"If that's all it is, and it's simple and makes you think about what you're doing, it's a good thing."
The four keynote speakers at the symposium include retired United States Department of Agriculture employee Dr Lars Anderson, Conservation Minister Eugenie Sage, Ecologic Foundation member Guy Salmon and Bay of Plenty Regional Council chairman in Lake and Fresh Water Science Professor Troy Baisden.
The full programme and registration can be accessed from the society website.
Managing aquatic pests in Rotorua's lakes
Aquatic pest weeds such lagarosiphon, hornwort and Egeria densa are controlled through:
- maintenance of weed cordons at selected boat ramps
- application of approved aquatic weed sprays in affected lakes (by Land Information New Zealand)
- presence of lakeside signage and delivery of check, clean, dry messaging at boat ramps during key times of the year using staff and summer students
Pest fish management is currently limited to catfish and includes:
- the largest fyke netting programme undertaken in NZ
- surveillance of surrounding lakes
- support of community-driven control programmes in partnership with Te Arawa Lakes Trust
- investment in six different science initiatives, and
- ongoing promotion of the check, clean, dry messaging (up weighted over the summer months)
- Bay of Plenty Regional Council