What analysis, if any, has been undertaken on the temporal spread of Corbicula fluminea since its initial detection, including evidence of any spread beyond the Waikato catchment?

Answer

I am advised that, after the initial detection, a delimitation survey was conducted along the Waikato River and Lake Taupo to determine the current range of Corbicula fluminea. Additionally, waterbodies throughout New Zealand that are highly connected by people, craft and equipment to the Waikato River were surveyed for Corbicula fluminea presence using environmental DNA sampling methods. I am advised that, in the three years since it was first detected in New Zealand, Corbicula fluminea has not spread beyond the Waikato River and the detection in Lake Rotomanu in Taranaki. We are continuing surveillance to monitor for any spread.