Rotorua lakes are being checked for an invasive Asian freshwater clam which was recently discovered in the Waikato.
Biosecurity New Zealand announced earlier this month that the freshwater gold clam was present along a 50km stretch of the Waikato River, Bay of Plenty Regional Council said in a statement today.
With up to 20 per cent of visitors to the Rotorua lakes coming from the Waikato, Bay of Plenty Regional Council and Te Arawa Lakes Trust staff have begun surveillance.
The council’s biosecurity team leader for marine and freshwater, Hamish Lass, said they had completed snorkel surveillance at all the high-risk sites and found no evidence of the freshwater gold clam.
“This included around the boat ramps at the busiest lakes, which have lots of events and visitors coming from out of the region.
“Another key part of the response has been to undertake environmental DNA (eDNA) testing in key locations, which will flag the presence of the freshwater gold clam if it is in the water.
“We are awaiting the results of the first samples taken, and plan to continue with this form of sampling longer term,” he said.
Biosecurity New Zealand said these clams, which grow to only 2 or 3cm in length, could breed rapidly, with each adult being able to produce up to 70,000 juveniles a year and when present in large numbers, could clog up water-based infrastructure such as electric generation plants, irrigation systems and water treatment plants.
Te Arawa Lakes Trust operations manager, William Anaru, said given the freshwater gold clams were filter feeders there was a real concern about their potential environmental impact.
“As the clam has never been found in Aotearoa before we just don’t know what impact they are likely to have on our native taonga species, such as kākahi.
“We know that this clam has become widely established in North and South America and Europe, and to date, eradication hasn’t been possible. This means that preventing the freshwater gold clam from entering the Rotorua Te Arawa Lakes is a priority.”
Lass said this was a timely reminder for all lake users to always ‘check, clean, dry’ when moving between waterways, and to follow the regional rules around certifying that their equipment is clean of invasive freshwater weeds or pests.
“By making sure people are self-certifying, as is required when using the Rotorua Te Arawa Lakes, we can help to prevent the clam making its way into the region, as well as any other unwanted freshwater pests.”
If someone thinks they have seen the freshwater gold clam, they should note the location and take a photo if possible. They should then either phone Biosecurity New Zealand on 0800 80 99 66, or complete the online reporting form at report.mpi.govt.nz