Fish Facts

FISH FACTS: “Shellebrations” at Noosa

Wednesday 7th September 2022 was a big day in the life of the Noosa River, as it marked a “Shellebration” of the official start of the Noosa River Oyster reef restoration project. Image: Dr Ben Diggles

LIKE most estuaries along our southern and eastern coastlines, the Noosa River estuary has endured its fair share of impacts from Australia’s relentless coastal development. Formerly a sleepy fishing village, the transformation of Noosa began in earnest in the early 1970’s with the Noosa Sound development, and accelerated from there. In the late 1980’s I well remember catching my first tarpon, after sleeping overnight under a bridge at one of my favourite Noosa fishing spots. The fact that very same spot soon became the Noosa Sheraton Hotel (now Sofitel Noosa Resort) says it all. To long term visitors the modern Noosa today is unrecognisable in many ways, with the only constant being the river itself.

Of course, the development of the river catchment and rapidly increasing human population at Noosa has had a plethora of negative effects on the river. Over the years these have manifested in various ways, firstly in historical terms through complete loss of once important industries such as the commercial oyster fishery, which ceased around 100 years ago in the 1920’s. Then, as outlined in a report by historian Ruth Thurstan from the University of QLD, fisheries data and anecdotal evidence have both indicated significant reductions in commercial and recreational catch rates of prawns and many popular fish species from the 1920’s onwards.

More recently, the scale of the losses of aquatic biodiversity and biomass in the Noosa River have been scientifically verified. In the first decade of the new millennium, we saw evidence of declines in water quality due to pesticide contamination. These were expressed through the emergence of fish health issues involving two headed Australian bass larvae at a once productive and reliable fish hatchery located near Boreen Point in the upper Noosa River. Then in 2018, researcher Greg Skilleter and his team from the University of Queensland were repeating aquatic biodiversity studies they had conducted at Noosa back in 1998. They found that comparisons of data collected in 1998 with samples from 2018, taken in exactly the same sections of the Noosa estuary, identified declines of 74-84% in both the number of species and overall abundance of polychaete worms, amphipods, bivalves and snails within the sediments. All of these invertebrate species are critical component of the bottom of the estuarine food chain, due to their roles as food for fishes, crabs and prawns, and as major bioturbators (irrigators of the sediment, allowing oxygen and nutrients to be recycled), and sediment stabilisers (stopping sediment resuspension through the formation of binding tube mats). In other words, eutrophication and sedimentation from development of the Noosa River catchment had bought anoxic layers of black coloured sediment very near the surface, overwhelming and effectively choking the life out of around 80% of the animals that make up the lower parts of the estuarine food chain. When that happens, and their food supply disappears, it is no secret where all the fish have gone.

Such was the extent of the loss, being good scientists Skilleters team were skeptical and repeated the 2018 sampling at their own cost. But the results rung true, with 60-70% losses still observed, providing a rare window into the decline of the health of an Australian estuary. Indeed, Skilleters results have highlighted a scary, yet probably typical decline which has no doubt occurred time and again out of sight and out of mind, along thousands of kilometres of Australian coastlines, wherever extensive catchment development and urbanisation has occurred.

Of course, for many people in the Noosa region this unwanted news came as a shock. Denial was a common emotion often expressed by those new to the area, or those who evaluate ecosystem health by the sunlight glinting off the water surface, rather than the biological functioning of what happens underneath. But the news was not new for long term local fishers, who had experienced the catch rate declines first hand, nor to myself or other researchers who have studied the biological decline of these ecosystems.

The only good thing about all this is that you need to understand the extent of what has been lost before there is any chance of getting community buy in to begin the recovery. This is why groups like The Nature Conservancy, the Thomas Foundation, Noosa Shire Council, OzFish Noosa and the Noosa community have committed to rebuilding oyster reefs along the Noosa River. Their loss over 100 years ago signalled the start of the decline in the health and resilience of the Noosa River system, which has continued until this day. If this decline is to be reversed, restoration of the lost shellfish reefs is a critical part of the process, together with improvements in the catchment to suppress sedimentation and improve runoff water quality. Wednesday 7th September 2022 was a big day in the life of the Noosa River, as it marked a “Shellebration” of the official start of the Noosa River Oyster reef restoration project. In the construction phase of the project (which is supported by the Australian Government’s Reef Builder program), marine contractors have deployed rock foundations onto the riverbed in special configurations to create oyster reef patches at 4 different locations along the river. The rocks will then be seeded with cleaned and sanitised oyster shells which will attract and catch wild oyster spat, rebuilding the reefs over time. The locations of the reefs are as follows:
Site 1: Goat Island – centre of the southern shoreline, landward of the formal moorings.
Site 2: Tewantin shoreline – upstream of the boat ramp below the council chambers.
Sites 3 and 4: Noosa Sound – east and west.

Oyster reefs were also culturally important to Noosa’s traditional custodians, the Kabi Kabi Nation, who fished them sustainably for many thousands of years. This was best said by Kabi Kabi elder Fred Palin, who stated in his welcome to country for the shellebrations “Restoration of the shellfish reefs therefore represents a significant reconciliation step to renew the cultural links of the Kabi Kabi to their sea country.”

“Our first priority as part of the reconciliation process is to reach out to all people of South East Queensland who are interested in our Country and Culture, and to invite them to play an active role in caring for our part of this Earth. The Earth is our Mother. As she is healed so will we be healed.”

It’s great to finally see recognition that “Restoration is Reconciliation”. This goes to show how closely the wants of rec fishers for healthy fish habitat align with the desire of indigenous groups to care for their sea country. Let’s hope that in shellfish reef restoration efforts and other fish habitat projects around Australia, that both groups can combine to realise these worthy goals for many years to come.

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