High water temperatures trigger Geographe marina fish kill

People are warned not to swim or eat seafood from the Geographe marina following dead crabs and fish being found in the area.

The Department of Health issued the advice after 20 crabs and a flounder were found dead at the marina on Friday, November 24.

In a statement the department said that swimming in areas of water with large numbers of dead and decomposing fish was “dangerous to human health, due to potentially very high levels of harmful bacteria”.

“For the same reason you should not collect, and use dead fish for bait, or consumption from an area impacted by a fish kill,” it read.

“Until it is deemed safe to do so, do not fish, or collect or consume fish from the waters near a fish kill.

“Remember to take care of your pets too. You should prevent your pets and other animals from coming into contact with dead or decomposing fish either in the water or on shore.”

The initial fish kill involved about 20 blue swimmer crabs reported to be immobile, but alive, on the beach on the western side of the marina, which were found dead when the site was inspected by authorities. The dead flounder were found later that evening.

The Department of Primary Industries and Regional Development is liaising with the Department of Transport and, the Department of Water and Environmental Regulation on the fish kill.

DPIRD believed the fish kill was likely due to decreased dissolved oxygen levels within the canal caused by a combination of high water temperatures, a build-up of decomposing sea grass and seaweed and a temporary disturbance of this decomposing material during maintenance dredging in the marina.

The Department of Transport has a dredge management plan and completes environmental monitoring during the annual dredging operations.

DoT said the dredging removes marine sands and decomposing sea grass and the seaweed that accumulates after winter storms, and helps maintain safety for the boats operating in the marina.

The Health Department said while the fish kill appears to have passed, the risk of further fish kills in the marina remains high with the very warm weather and the continued dredging.

Fish kills can be reported to FISHWATCH on 1800 815 507.