Methodology

This indicator reconstructs data from previous reported arrival events provided by Department of Energy, Environment and Climate Action (DEECA)'s Marine Biosecurity team at Agriculture Victoria to monitor the rate of introduction of NIS and whether is has increased or decreased in recent decades. Reported arrivals are those that have been reported to occur in Port Phillip Bay and do not include those that may be attached to boat hulls on transient vessels. Not all introduced marine species become invasive (have the potential to cause negative impacts), but monitoring the arrival of NIS is important to help mitigate potentially invasive species that could threaten our environment.

Importantly, this indicator depends on the monitoring effort and early detection and documentation of NIS. Hence, the arrival of some species may have occurred earlier but were not reported or detected until a later date. The NIS arrivals indicator may be revised with revised marine species arrival dates.

To align with the Port Phillip Bay Environmental Management Plan 2017-2027 (EMP) reporting framework, status categories for the NIS arrival indicator have been developed. The Very Good category aligns with successful prevention and biosecurity mitigation of the arrival of NIS, compared to the Very Poor category which reflects a state where many NIS have arrived, biosecurity measures are ineffective.

A status trend will also be reported. This will indicate if the NIS arrivals indicator is Improving (less arrivals are reported), is Stable or is Declining (more arrivals are reported) since the last 5-year assessment period.

A confidence status is integrated into the approach to evaluate the method and data that the indicator is derived from, also aligning with other reported themes of the EMP. Confidence in the indicator to accurately represent the arrivals of NIS is defined by DEECA's Marine Biosecurity team at Agriculture Victoria, where the confidence is categorised as High, Intermediate or Low.