Judas carp tagged to shed light on their movement

on 01 Mar 2015 
Electronic tag being surgically implanted into one of the Judas carp which will show us where and when this pest moves along the river.

Six European carp were electronically tagged by NSW Fisheries staff at Scottsdale Reserve last week to help shed light on when and where carp move along the upper Murrumbidgee River. This information is currently a key knowledge gap in the upper Murrumbidgee catchment and is critical for the better management of this pest fish species in upland river systems. 

The six tagged carp will eventually make up a cohort of 30, which will be tagged later in the year when river temperatures cool. The movement of the tagged ‘Judas’ carp will now be tracked by hi-tech fish monitoring stations that we've deployed in the river (see post: Ready, Set,  Delpoy’ on Nov 2014) so they'll shed light on where and when carp move through the system, including at Scottsdale Reserve.

The monitoring system includes monitoring stations set up in the mouth of two tributary rivers upstream of Scottsdale Reserve, which are suspected breeding sites for carp.

This in itself is novel, because carp are thought to prefer large off-stream wetlands for breeding, rather than breeding in riverine systems. Tracking carp movement into these tributaries could indicate that in upland rivers carp may be using riverine habitat to breed where there are no large off-stream wetlands systems.

The fish tracking project is a collaboration between Bush Heritage Australia, NSW Trade and Investment (Fisheries) and Prue McGuffie (PhD research student).

The project will also tag and track native fish species so the movement of carp and native species can be compared to see how carp and native species overlap.

This information will be used to indicate whether carp could be impacting native fish breeding (for example by eating their eggs) and so perhaps be a factor affecting recovery of our native fish populations, which are in severe decline. 

This is critical information because the upper Murrumbidgee River is the home of four nationally listed threatened fish species, three which have now been found at Scottsdale Reserve (yes THREE!).

The carp tracking program is a key part of the Upper Murrumbidgee Demonstration Reach (UMDR) Carp Research project, which aims to address key knowledge gaps about the impact of carp on native fish species in the upper Murrumbidgee. 

Another key part of the UMDR Carp Research project is Scottsdale Reserve’s carp trapping program which is aiming to test the effect of reducing carp competition to enhance native fish populations (see ‘Monster Murray cod to benefit from carp trapping program at Scottsdale’ Aug 2014).

Carpe diem.

Electronic tag being surgically implanted into one of the Judas carp which will show us where and when this pest moves along the river.