Fish kill events
A fish kill event involves the death of a large number of fish or other aquatic animals (such as crabs or prawns) over a short period of time and often within a defined area.
Fish kill events can occur due to a wide range of factors including:
- natural spawning and migration events
- diseases including susceptibility to disease due to stress of poor water quality
- low dissolved oxygen – this can be caused by decay of algal blooms, decay of other organic matter, coral spawning, poor mixing of a water body
- sudden change in water quality such as salinity, pH, turbidity, dissolved solids or temperature.
- contaminants such as hydrogen sulphide, carbon dioxide, ammonia, methane and other contaminants, including metals
- physical irritants – such as suspended sediment, algal cells and bacteria that interfere with fish gills
- algal toxins, which are produced by some species under certain conditions.
The Department of Water and Department of Fisheries jointly manage the state's Fish Kill Response protocol. We need members of the public to report incidents as quickly as possible so that we can respond.
If you see a fish kill please report it immediately to:
- the Department of Fisheries 'FishWatch' hotline 1800 815 507 (24 hour service)
- your nearest Department of Water or Department of Fisheries office
- the Swan River Trust (for the Swan Canning Riverpark) on 9278 0900 or after hours on 0419 192 845.
For your safety please do not:
- touch the dead or dying fish, or the water in the area
- collect fish for samples or use as bait
- eat any fish caught in the area of the event
Some of the factors contributing to fish kills and the connection with algal blooms, are summarised in the diagram below.
Factors contributing to fish kill and algal bloom events