The Department of Primary Industries and Regional Development, Fisheries Division have investigated a marine fish event north of Bunbury at Belvidere Beach beginning on Thursday, 24 August 2017.
The results of the investigation are as follows:
* Testing was limited due to the lack of fresh samples of dead crabs. However, the blue swimmer crab sample submitted to the Department’s Fish Health unit returned a negative test result for white spot syndrome virus (WSSV).
* There were also no significant findings from water samples submitted for analysis.
* Fisheries scientists have advised that blue swimmer crabs are at the edge of their distribution range in the south west region of WA and are therefore more sensitive to small environmental changes.
They have further advised that varying local environmental conditions at the time may have stressed the crabs further and contributed to their deaths. These include:
* An increase in sediments (inorganic salts and organic matter) from the Collie and Preston rivers which may be linked to the observed increased turbidity.
* A lower than average air temperature – two degrees lower than average during the seven days leading up to the fish kill. Fluctuations in river water temperatures were also observed.
Any fish kills should be reported to the FishWatch 24 hour hotline on 1800 815 507.