Artificially high flows in the Goulburn River could damage fish spawning and wreck the multi-million-dollar recreational fishing industry, a peak fishing body has warned.
The warning comes on top of criticisms from environmental groups which are also worried about the inter-valley transfers of water from the upper catchment to the lower reaches of the river due to irrigation demands.
VRFish, the peak body for recreational fishing in Victoria, is seeking the intervention of the Federal Water Minister David Littleproud to halt the transfers.
Recreational fishers are angry that unprecedented levels of inter-valley transfers are ruining the recreational fishery and damaging the river ecosystem that native fish rely upon.
Victorian Recreational Fishing chair Rob Loats said nearly a third of all inland
recreational fishing in Victoria occurred in the Goulburn River catchment.
“Recreational fishers, catchment managers and fisheries managers have spent decades investing in improving native fish populations in the lower Goulburn River and creating arguably the best inland fishing opportunities in Victoria,” Mr Loats said.
“The impact to our recreational fishery from IVTs is through unseasonably high water flows and cold-water pollution. This plays havoc with our native fish's natural time clock, impacting growth, survival, recruitment success and catchability.
“Over summer in normal conditions, water temperatures rise which get the fish on the bite as they are right in the middle of their growing season. Juvenile fish born over the spring need calm, warm and productive waters — not a fast flowing, cold river.
``Unprecedented levels of IVTs being released down the Goulburn River is to service water users downstream on the Murray River and in South Australia. Prior to 2017,
water demands being fulfilled by these IVTs would have been largely serviced from the
Darling or Murrumbidgee systems, however, little or no water is available.”
Mr Loats said recreational fishers could no longer stand by and accept the lower Goulburn River being used as a water pipe.
Goulburn Broken Catchment Management Authority chief executive officer Chris Norman said there was evidence that inter-valley transfers down the Goulburn River in the warmer months caused bank erosion, damaged bank vegetation and reduced slack water.
Plants and slack water provide valuable food and shelter for native fish.
“While some monitoring of native fish has been done recently it is too early to make any definite statements on the effects of high unseasonal flows (IVT) on native fish numbers,” Mr Norman said.
“Fish ecologists are concerned that the unseasonality of continued high summer flows has a negative impact on native fish recruitment and survival, particularly small-bodied native fish such as the threatened Murray River rainbowfish.”
Australian Fishing Traders Association board member Steven Threlfall said the transferring of water downstream to users on the Murray River and in South Australia was destroying the river banks and the vegetation these fish needed to survive.
While water temperatures generally rise during summer creating a calm, warm and productive environment for fish to grow, Mr Threlfall said IVTs were dropping this temperature and speeding up the river flow.
‘‘The temperature doesn’t help fish breeding and doesn’t help the young smaller fish that we actually put in the rivers; as far as stocking systems go, it doesn’t give them the right conditions to grow out. It’s too cold for any breeding,’’ he said.
The damage caused to the Goulburn River by transfers of irrigation water dominated a forum to talk about environmental water for the river in Shepparton in July.
Stakeholders invited to the forum wanted assurances that the shifting of large volumes of water would not continue to cause damage, and they also wanted to know how the impact was being assessed and if the damage was reversing the effects of managed environmental flows.