It is certainly a tough time for all on the land at the moment with so much of our sunburnt country declared in drought.
Our thoughts are with all those families who are struggling to make it through and we all hope the drought busting rains arrive soon.
These tough conditions are also having a massive impact on our native marine inhabitants as well.
Waterways are drying up fast and creating a lot of pressure on the health of the animals that call this home and the quality of the water in which they live.
There have been numerous reports of large fish kills that are a result presumably from low dissolved oxygen in the water column.
These events are taking place all over the drought affected regions at an increasing rate.
Pindari Dam was the site of a particularly sad scene lately when the dam water reportedly ‘rolled over’ creating a very stressful situation for the native species.
This rollover occurs during periods of low water, mainly in impoundments and storage dams, however it has also been known to occur in our river systems as well.
The main catalyst is minimal inflows and stagnant conditions which results in layers forming within the water column of various Dissolved Oxygen levels and temperatures.
When the water layers reach certain conditions generally triggered by a temperature change or even a sudden inflow of water, it creates a rapid change in conditions that the fish living in these zones can’t adapt to quick enough.
The main causes of death are generally suffocation due to a low Dissolved Oxygen content available for gill breathing animals and unfortunately it is the larger fish that will die first due to their higher oxygen requirements.
Over the last 30 years we have seen a steady rise from only 10 fish kill events per year in the early 1980’s up to today where it is not uncommon for 60 -70 events to be recorded each year.
This same time period has also averaged the driest period on record as well, you add to this the record number of stocking programs adding load to the system and an improved awareness and reporting ethos it would be reasonable to assume there are many factors at play in why these kills are increasing.
If you see a fish kill event please report this ASAP to a Fisheries Officer or the Office of Environment and Heritage.
