Judas carp will help shed light on pest fish movement in the upper Murrumbidgee

on 04 Mar 2015 

Six European carp were electronically tagged by NSW Fisheries staff at Scottsdale Reserve this week in an effort 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 carp which will be tagged later in the year, when river temperatures cool down.  The movement of the tagged ‘Judas’ carp will now be tracked  by hi-tech fish monitoring stations which we have previously deployed in the river (see BHA blog post: Ready, Set,  Delpoy’- 17 Nov 2014).  In this way, the tagged fish will 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 which are suspected breeding sites for carp.  This in itself is novel, because carp are thought to prefer large off stream wetlands to breed, rather than breeding in riverine systems.  Tracking carp movement into these tributaries systems could well be indicate that in upland rivers carp may be utilising riverine habitat to breed due to the absence of large off stream wetlands systems.

This fish tracking project is a collaboration between Bush Heritage Australia, NSW Fisheries, the Capital Region Fishing Alliance, the NSW Recreational Fishing Trust and Prue McGuffie( PhD research student).  The project will also track native fish species time so the movement of carp and native species may be compared.  This will aim to investigate how carp and native species overlap. This information will be used to inform the theory that carp impact native species through competitive pressure and are likely to be a factor in preventing the recovery of our native fish which are in severe decline.  This is critical 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!- this is breaking news and a blog post is imminent). 

The carp tracking program is a key part of the Upper Murrumbidgee Demonstration Reach 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 BHA blog post: ‘Monster Murray cod to benefit from carp trapping program at Scottsdale’- 10 Aug 2014).

Carpe diem.