Probe completed on two WA fish kill incidents

The Western Australia Department of Primary Industries and Regional Development (DPIRD) has concluded its investigation into two localised fish kill events at Port Geographe Marina that occurred within a marina canal on the 12th and the 29th of November 2022.

DPIRD liaised with the Department of Transport (DoT), the Department of Health, the Department of Water and Environmental Regulation (DWER) and the City of Busselton.

The department has also relied heavily on the advice and analysis of various experts including DPIRD’s Diagnostics and Laboratory Services and DWER’s Phytoplankton Ecology Unit.

DPIRD believes these fish kills were most likely due to decreased dissolved oxygen levels within the canal caused by a combination of high water temperatures, a build-up of decomposing seagrass and seaweed and a temporary increase in water turbidity from maintenance dredging in the marina. The affected canal is also located in an area of reduced water mixing, which can also lead to decreased dissolved oxygen levels.

Maintenance dredging is required annually to maintain safe vessel passage by removing marine sands and decomposing seagrass and seaweed that accumulates after winter storms and to assist in maintaining water quality.

DoT is now reviewing its management plans in preparation for further dredging in the marina.

More fish kill​ information can be found on DPIRD’s website.

The best way the public can help is by reporting fish kills to the FishWatch 24/7 reporting service on 1800 815 507, or lodge it through the online form on Crimestoppers​.

When making a fish kill report, the public is advised to indicate where it occurred and what was seen, including numbers of dead fish and, if possible, the species affected. GPS coordinates and/or photographs will also assist the DPIRD’s investigation.