Plan B for Salmon Ponds

IT’S a showplace, the oldest trout hatchery in the Southern Hemisphere, and the origin of a multi-billion-dollar industry that today encompasses Australia and New Zealand. But Salmon Ponds very nearly wasn’t. 140 years ago, the first European settlers were a very long way from home and from the familiar. They asked themselves a deeply important question: what could the soils and waters of this new terrain furnish to a growing population? One choice was salmon.

For those of European stock, it was a known quantity, like the food crops they planted. In the right place, salmon grew quickly and in large number. Little was needed by way of fencing or feeding. The difficulty, of course, was the same one with which the newcomers had to contend from the day they stepped off a boat. Everything, including the salmon, was 17,000 kilometres away in England. In the day, for live fish or fish eggs, that was a hugely perilous multi-week journey.

There were several failed attempts, but finally on May 4, 1864, the ‘Norfolk’ succeeded in landing both salmon and viable eggs, along with some trout eggs. While the Salmon Ponds, under the watchful eye of a pastoralist named James Arndell Youl, had been well-prepared for salmon hatching, the next step was even more fraught. Grown to maturity, a small number of salmon hatched at the Ponds were released with the expectation they’d return to the nearby Derwent River. The thinking was that salmon would become a self-sustaining population. Instead, the salmon disappeared. But a Plan B emerged.

Work with the survivors of 2700 live brown trout ova that had also been packed inside 30 tonnes of ice on the ‘Norfolk’ proved effective. In fact, in the waters set aside for salmon at the Ponds, the young trout thrived. And when released into Tasmania’s fresh waterways, lakes and streams became the self-sustaining fish population Youl and the Ponds’ superintendent William Ramsbottom had envisaged. Over the decades, they became the root stock of fisheries across Tasmania, the Australian mainland and New Zealand. Today, it’s estimated some three million trout are released each year into those recreational fisheries in the colder waters of not only Tasmania but Victoria, NSW and West Australia. And it’s the colder waters that are the key, says Brett Mawbey, who’s the Manager Hatchery and Stocking for Tasmania’s Inland Fisheries Service. It’s also why Salmon Ponds core role as a fish hatchery has now changed. In summer, the Derwent Valley is regularly one of the hottest places in the state, Mawbey points out. And the heat – even with the cooling effect of the deep tree canopy at Salmon Ponds – makes for a poor fish ecosystem.

“Think of it this way,” he says. “Where you’ve got a lot of fish, a large ‘biomass’ in a relatively small, shallow space, there’s a real and rapid impact on water quality. These are not optimum conditions. Then add the high temperatures of summer.‘’ Fish quickly show they are not doing well, he adds, particularly if the water is too warm, or they’ve become too crowded. “Simply,” he says, “they stop eating.”

In 2022, Inland Fisheries maintains the Salmon Ponds as a small-scale operation. “It’s a display case,” says Mawbey, not unkindly, “a recognition of its history as the oldest hatchery in the Southern Hemisphere, the birthplace of our trout fishery.” Inland Fisheries’ real work today is relocating wild trout in the lakes of Tasmania, to which they’ve long adapted. It’s here in these cold waters that ova are harvested, largely from wild brown trout.

They will be grown through five stages into juvenile fish by the IFS in a series of troughs and ponds in a designated area at the Salmon Ponds. These days a smaller amount are reared for supplementary stockings around Tasmania in the cooler months. “We get better value out of these wild fish transfers in managing, protecting, regulating and stocking our waters,” says Mawbey. “And that’s our core role, our bread and butter. “These days, we only stock waters when wild populations are not being maintained naturally, and for that reason prefer wild fish whenever possible,” continues the IFS manager.

“Yes, we sometimes draw from our Salmon Ponds stock when needed. We can also raise fish such as the Tiger (hybrids) and Albino trout, to replenish the display ponds situated in the heritage gardens.” More, Inland Fisheries maintains arrangements with private landowners with fishing lakes and dams, supplying such angler favourites as rainbow trout, an application and permit is required.

Another call on Salmon Ponds is for fish to stock lakes for junior angling event days, including those at Longford, Latrobe and at Bushy Park, and for the big annual angling expo at Cressy. From that perspective, it looks like Plan B – the ‘B’ for brown trout – has worked out pretty well.