The Blue-billed duck is just one of the species threatened by introducing trout into Devilbend Reservoir. Image: Valorix.The Department of Primary Industries (Fisheries Victoria) has stocked the Devilbend Reservoir with Brown and Rainbow Trout despite studies that advise the introduction of alien fish species will jeopardise populations of vulnerable native fish and birds.
“I think the decision has been made, and will be made in the absence of any scientific advice, in fact it may even be made in direct contradiction of scientific advice,” said Dr Ross Thompson, co-author of Devilbend Aquatic Habitats Ecosystem Study.
Thompson was contracted by Parks Victoria to undertake one of numerous studies they commissioned as part of a two year process involving community groups and recreational fishing interests to approve public access into the reserve.
Recreational fishing at Devilbend Reserve requires the water to be stocked with fish suitable for angling.
Thompson said there is a “genuine risk” to the native fish at Devilbend. He is concerned about the vulnerability of native fish to predation by introduced fish species.
Fisheries Victoria’s Translocation Risk Assessment for Devilbend and Bittern Reservoirs for stocking recreational (fish) species states that the Reservoir will overflow once every two years. According to the study, the introduced fish will then reach the Devilbend and Balcombe Creek system.
This prediction is alarming, as the creek system contains Dwarf Galaxias (Galaxiella pusilla), a native fish listed as ‘vulnerable’ under the Environment Protection and Biodiversity Conservation Act 1999 and declared ‘threatened’ under the Victorian Flora and Fauna Guarantee Act 1988.
Dr Thompson warned that Dwarf Galaxias are extremely vulnerable to predation by salmonids, a family of ray-finned fish.
The Risk Assessment states that the risk rating for impacts of predation on the Dwarf Galaxias population is high, and the consequences to their population long-term.
Victoria’s Department of Sustainability and Environment has a National Recovery Plan for the Dwarf Galaxias that names both Fisheries Victoria and Parks Victoria as responsible for the species’ management.
The Recovery Plan recognises a Galaxias population in Devilbend Creek. The management practices to avoid threatening processes believed to be responsible for their decline recommend that proposals to translocate aquatic species into Dwarf Galaxias’ habitat be subject to relevant risk management processes.
“The Translocation Evaluation Panel (TEP) have considered those risks and considered that they are not significant,” said Chris Hardman, Parks Victoria’s Melbourne Regional manager.
Hardman said that the hydrology had not yet been resolved, and until water was put in the reservoir to maintain water levels it would not overflow.
“The TEP considers all risks, and then they determine whether those risks can be managed. In the case of Devilbend, the panel have recommended that it is an appropriate waterway for stocking. That’s based on all of the research, all of the science, all of the reports.”
Christopher Collins, Executive Officer of Victorian Recreational Fishers’ representative organisation, VR Fish, said he had seen the TEP risk assessment.
“I can assure you that I didn’t see anywhere where the words ‘big risks’ were written, there are risks, absolutely, but the risks according to that report are manageable.”
A pair of White-bellied Sea Eagles and Blue-billed Ducks, both threatened species listed under the Flora and Fauna Guarantee Act 1988, also inhabit the reserve. Devilbend is the only known nesting site for the White-bellied Sea Eagle on the Peninsula.
Ornithologist Roger Richards said trout will eat the invertebrates these birds feed on.
“You’re taking away a lot of the food that the Blue-billed Ducks need.”
The Impact of recreational access and stocking with fish on waterbirds and shorebirds – Devilbend Reserve Study, conducted by the Arthur Rylah Institute for the Department of Sustainability and Environment, states that the Blue-billed Ducks are a priority species for conservation at Devilbend and there are strong reasons to resist stocking the water with fish.
The Impact Study states that evidence suggests stocking with fish would also have adverse effects on a wide range of waterbird species at Devilbend Reserve.
But Chris Hardman believes that measures have been taken to avoid this.
“Angling access has been restricted to four spots around Devilbend, so the vast majority of the shoreline is free from human activity, which ensures the protection and refuge for wildlife,” he said.
“The parks are for people to use and enjoy.”
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