All photography provided by Robbie Porter
OzFish Unlimited - Moreton Bay - Shellfish Reef Project
Moreton Bay (Quandamooka) has lost many thousands of hectares of fish habitat such as seagrass and saltmarsh but by far the biggest loss has been that of shellfish reefs, with studies showing around 95% loss of suitable shellfish reef habitat in western Moreton Bay. These largely unseen and lesser known reefs were once the life blood of our bay. This project aims to expand the knowledge base needed to restore these reefs.
What happened to the reefs?
Since European settlement of Australia, oysters in Moreton Bay and other areas have been harvested for food and the lime in their shells. This lime was used to make cement and helped to build many of Brisbane’s historical buildings. Sadly today shellfish reefs are considered functionally extinct. The sea floors have been damaged by dredging, siltation and eutrophication and today shellfish larva (Spat) have no clean subtidal structures to attach and grow on.
What are shellfish reefs and why do we need them?
Shellfish reefs are living ecosystems. They are made up by many different types of shellfish but in Moreton Bay the main 3 reef forming species are; Rock Oysters (Saccostrea glomerata), Pearl Oysters known locally as Quampies (Pinctada albina sugillata) and Hairy Mussel (Trichomya hirsuta). The image below shows a cluster of these three species. The cluster in this photo is from a small remnant Shellfish reef near the mouth of Myora Springs on Stradbroke Island.
These shellfish create complex vertical structures which make ideal homes, breeding locations and food sources for a vast array of invertebrates and fish. Overseas, it has been shown that every hectare of living shellfish reef produces an additional 2.5 tonnes of harvestable fish each year.
One of the most important things about Shellfish is that they are natures water filters. A typical adult Sydney rock oyster can filter over 100 litres of water every day. The extent of the lost filtration services in Moreton Bay has not yet been calculated, however for similar systems overseas it has been shown that oysters used to filter the entire volume of water within large bays and estuaries, providing exceptional water clarity that promoted seagrass growth.
Who will benefit?
703,000 people recreationally fish every year representing 17% of all Queenslanders. This makes recreational fishing one of our most popular pastimes.
Restoring shellfish reefs will benefit;
· Amateur and commercial fishers by increasing the number of fish that can live and breed in the bay.
· First Australians by reconnecting them with their sea country (oysters were historically an important traditional food source). Quampies are still revered by many Indigenous Australians in our local area.
· All bay users including; bathers and casual day users, boat users, charter and tour operators, scuba divers, school science groups and many more by improving water quality and ecosystem health.
Who are we?
OzFish Unlimited is Australia’s premiere recreational fishing conservation organisation committed to restoring fish habitat. We are supported by several major corporate sponsors, an army of volunteers and Indigenous groups. We work closely with many other environmental restoration organisations and scientists.
How will we restore reefs?
More than 300m3 of oyster shell is dumped into landfill every year in Brisbane alone. We divert and recycle some of this shell that we collect from oyster farmers, wholesale oyster handlers and restaurants. We estimate that this will save a minimum of 150 cubic meters of landfill every year. We will treat the shell to eliminate biosecurity risks and turn this waste into a valuable resource, recreating lost shellfish reefs in Moreton Bay.
We collect oyster shell from farmers, seafood businesses and restaurants and take it to our Oyster Shell Recycling Facility is at the Port Of Brisbane. We wash and dry these shells in the sun for 4 months to sterilise them. These clean shells are placed into “Bio Block” moulds and biodegradable scaffold structures that will be transported and placed at strategic locations in subtidal and intertidal restoration sites throughout central Moreton Bay where we monitor and report on the growth of these oysters and the use of these reefs by fish and invertebrates.
These modular reef restoration structures will be positioned in areas outside of green zones where oyster reefs previously existed in locations that will not detrimentally affect seagrasses, wading birds, commercial fishers and wormers or create boating navigation hazards or amenity. We will monitor the results of these trials together with University researchers and aim to scale up the most effective restoration methods over the coming 10 years with the goal of restoring 100 hectares of oyster reef in a decade (with a potential to regenerate up to 250 tonnes of seafood per year).
This project is an essential step toward scaling up restoration of shellfish reefs in Moreton Bay. The successful implementation of this plan will open the way towards ultimately restoring many hectares of aquatic habitat which will improve the overall water quality, environmental diversity and health of the Moreton Bay ecosystem.