Barra surviving in Hazelwood Pondage

There’s good news for at least some of 5500 stocked barramundi in Hazelwood Pondage in Victoria. The tropical native fish are surviving well outside their usual range thanks to large volumes of warm groundwater being pumped from the local mine site into a channel, a situation that will continue for at least the next four years. But then what?

Despite local power station turning off the hot-water outlet after they closed their coal-driven power plant in late March 2017, a strong population of barra has now survived in the upper warm channel where the water source is 40C, Fisheries Victoria reports.

However, water temperatures in the main Pondage have fallen to 14C and will plummet further as winter approaches. It is anticipated fish kills will occur, as has already been the case for introduced tilapia.

While barramundi are more tolerant of cold water, they prefer water temperatures of 24C-30C and won’t acclimatise outside that range. They will be slower to succumb, a fact that is now driving rescue efforts by Fisheries.

The department recently caught and transferred 150 barra from the Pondage to the upper channel where the warm water continues to flow. They used electro-fishing methods to catch and release the fish.

There is also evidence of barramundi moving into the warmer waters of the channel on their own accord. The fish in this area are expected to survive through winter. This channel is currently off limits to fishing, although Fisheries is exploring access possibilities.

Fisheries has also observed cichlid baitfish in the warm channel on which the barra will feed and is now doing everything it can to keep the unique southern barra fishery alive.

Large volumes of warm groundwater will be pumped from the mine site for at least the next four years, it says. As such, the barra in this channel will survive the winter until the main Pondage warms again. But it doesn't get to 24C in the main pond.

While most anglers welcome the good news, others question the point in struggling to keep the tropical fish alive in a dam in the middle of Gippsland. The social media sites of Fisheries Victoria have been swamped with divided opinion.

Melbourne University researchers are now looking at options to sustain the fishery well into the future. Hopefully, more good news follows.

An independent survey of 4000 boat-based barramundi anglers found the direct economic benefit of this fishery was between $600,000 and $800,000 over a four-month period, during which at least 5000 people visited the Pondage to fish for barra and caught fish to 80cm.

More on Hazelwood Barramundi.