THE NSW Department of Primary Industries has attributed large silt deposits left behind after flooding as the reason for a carp separation cage constructed as part of the $3.5 million Marebone Fishway project still left unused.
Although the fishway was officially opened on October 28th 2011, the huge stainless steel carp separation cage is yet to extract a single scale from the Macquarie River, with the impressive apparatus sitting high and dry and uninstalled.
A spokesperson from the Department of Primary Industries told Dubbo Catches that “Following the construction of the Marebone Fishway and Regulator, floods deposited significant sediment loads immediately upstream of the fishway where the carp cage was to be located. This sediment would have restricted the operation of the cage. State Water recently completed de-silting operations at the site following favourable flow conditions, with the cage available for insertion and operation for the start of the carp migration season, for example September, or contractor availability”.
In a media release issued by State Water for the opening of the Fishway in 2011, Minister for Western NSW and Member for Barwon, Kevin Humphries, said that “The carp trap takes advantage of carp’s tendency to jump over submerged obstacles, providing a mechanism to separate them from native fish species. By reducing numbers of migrating carp near the entrance to the Ramsar-listed wetlands, we are providing native fish with a better chance to thrive along the river”.
However, almost two years after the project was officially opened, a single carp is yet to be extracted.
A recent article in the Manning River Times stated that fisheries experts had found that carp numbers have increased by up to 4000 per cent in the past two years, with numbers set to increase further as juveniles from the breeding boom reach sexual maturity in the next year.
Drought-breaking rains in 2010 filled the state’s parched rivers, and the subsequent floods led to an outbreak of the invasive fish species, known as the rabbit of the waterways.
The chief executive of the Invasive Animals Co-operative Research Centre, Andreas Glanznig, said the carp competed with native fish for food and habitat.
”After the last major floods the number of new carp in the system increased by up to 4000 per cent,” Mr Glanznig said.
Females reach sexual maturity at three to five years of age and produce 1 million eggs, on average, when they spawn each year. Males can procreate from two years of age, which means those fish born after the drought will be ready to reproduce this spring.
