Time to address Carp problem

Dear Editor

There has been a lot of recent commentary around the explosion of European carp numbers and the damage they cause to our waterways.

Increased carp numbers are one of the unintended consequences of the Murray-Darling Basin Plan, however as we have unfortunately come to expect, those in charge of the plan are reluctant to acknowledge its adverse impacts.

It is worth noting the Arthur Rylah Institute for Environmental Research (ARI) ‘Managing Flows and carp - Technical Report Series No. 255’ which states that the carp population in the Lower Lakes was estimated to be 846,000 adult carp, but can hold a carrying capacity of nearly 4.2 million.

Research on carp breeding shows that inundation of floodplains provides the ideal breeding ground for carp, which adapt better than our native fish to hypoxic black water.

We know that carp are breeding in massive numbers right now, not just in the Lower Lakes but across the flooded Basin.

Those in the lakes will make their way upstream, others will cause localised damage in the Murray and its tributaries with the following consequences:

• They will invade native fish habitats, taking up living and breeding space

• They will steal native fish food sources

• They will muddy the waterways, creating a challenging environment for native fish

• They will damage aquatic plants by undermining their root systems or blocking out sunlight by dramatically increasing water turbidity

• They will eat native fish eggs and young fish, as both juvenile carp and adults are aggressive to natives.

Every time there is a flood, natural or manmade, we are enabling carp to breed and travel upstream.

Until we address this problem, the 'just add water' strategy that is presently being implemented just won't work for native fish.

Yours faithfully,

Darren De Bortoli,

Bilbul, NSW