How and why we are following native fish along the Upper Murray River
To help improve the management of Murray Cod, we are trying to answer a few questions.
1) When do Murray cod spawn and does this vary across the state?
2) What habitats do Murray cod use for spawning?
3) Are Murray cod spawning events successful?
Helping the river recover
We will also monitor the recovery of the waterway, due to bushfires followed by heavy rainfall in early 2020 which resulted in fish deaths.
How do we track fish?
Your browser doesn't support HTML5 video.
Once tagged, we can track Murray cod during the breeding season.
Using an antenna and a receiver, we are able to pick up the frequency emitted by each tag, which can be used to pinpoint the location of each individual fish.
Once we locate a fish that is believed to be on a nest. Visual assessment is undertaken with underwater cameras and light traps are used to sample larvae.
A simplified layout of light traps around a cod nest.
During Winter 2020 a total of 19 mature male Murray cod were tagged ranging from 48-109cm. Future tagging events are scheduled for early 2022.
A large number of juvenile and female Murray cod were also captured and released.
As of February 2021, 13 of the 19 fish have been tracked successfully.
The majority of the fish tracked had not moved far from their original capture location, with some found again several times.
Tracking will commence again in Spring 2021
Results from the Upper Murray will be compared to Northern NSW to better understand variations in Murray cod spawning across the state.
See Murray cod spawning and recruitment at the below link for more information.