Near real-time forecasting using operational oceanographic forecasting of contamination risk to reduce commercial shellfish harvest and beach closures (innovation fund)

Project leader: Ben Knight, Cawthron Institute

Safer beaches and kai moana

Seawater in Tasman Bay is periodically contaminated with bacteria, causing temporary closure of public beaches and commercial shellfish harvest. The aquaculture industry and Tasman District Council need more accurate and timely forecasting to better predict and manage risk. This project is creating the first near real-time forecasting tool for the region, which will improve the prediction of safe access to aquaculture sites and beaches.

Tasman and Golden Bays are at the ‘end of the pipe’ for discharge from local rivers and streams, so seawater is sometimes compromised by bacteria from land-based activities. This can affect the productivity and revenue of large shellfish growing areas and close local beaches to public use.

Although improved land management practices may ultimately reduce contamination risk, better forecasting is needed because the present rules result in conservative decisions – meaning some closures are unnecessary because bacterial levels did not breach the safety threshold.

A team of national experts from the Cawthron Institute, NIWA and MetOcean Solutions Limited are building connected models from the land to the region’s main rivers to the sea. These models will predict bacterial levels entering the sea, providing a visual spatial forecast (like a weather map) of contaminant risk. This will enable a timely risk assessment of contamination to beaches and shellfish growing areas.