The Department of Water has investigated dead fish in Parry Inlet 25km west of Denmark.  Following initial reports by members of the public to the Parry Beach camp site caretaker, a subsequent investigation by department staff discovered an estimated 1000 dead fish on the shores of the inlet.  Species present included bream, mullet, salmon, trout and king george whiting, with the majority being small hardyheads.  

Water samples were taken along the channel and several dead fish were collected and preserved in formalin for analysis.  Physical parameters were also monitored including oxygen, salinity temperature and pH. 

Analysis of water samples revealed that the probable cause of the fish deaths was a bloom of the microscopic algae Heterosigma akashiwo. This species causes oxygen stress in fish by clogging and irritating gills, but also by removing available oxygen from the water column. Heterosigma akashiwo occurs in a number of marine and estuarine environments, but usually occurs in small numbers which does not cause concern. Current low water levels due to a lack of rain, in combination with warm, still days have created ideal conditions for algal bloom events.

Signs have been erected at access points to the inlet advising the public of the fish kill event. The Department of Health has recommended that people avoid water activities in this area, and do not handle or collect any dead fish for bait or consumption. Anglers are also advised not to fish and people should keep their animals out of water until further notice. Department of Water staff will continue to monitor the situation.

http://www.water.wa.gov.au/News+and+events/Current+news/1307.aspx