Quilted oyster doonas bring versatility to shellfish restoration

OzFish Unlimited continues to innovate the shellfish revolution with the upcoming trial of quilted oyster doonas, set to bring an added layer of versatility to restoration projects.

OzFish Unlimited senior special projects officer shellfish revolution Robbie Porter, who invented the quilted oyster doonas, said: “No one has ever done something like this before and we think it could be really useful.”

The home-grown invention uses a non-degrading flexible gabion blanket that incorporates recycled oyster shells, which can be securely attached to rock walls, eroding banks and urbanised waterways, effectively transforming these structures into vibrant living seawalls.

“Effectively, the doonas are stainless-steel chicken wire that we make an envelope out of and put shells inside it,” Mr Porter said.

“To stop all the shells falling to one end, we quilt the chicken wire so that the shells are spread out evenly –much like duck down in a doona.”

As part of the restoration trial, OzFish will test the doonas through a partnership with The Southport School on the Gold Coast.

They will be trialed in the Nerang River in coming months.

Quilted oyster doonas are envelopes of stainless-steel chicken wire with shells inside, which are then quilted so the shells are spread out evenly.

The project should increase biodiversity and contribute to improved water filtration – bolstering fish numbers in the river.

One key aspect of their expected effectiveness lies in the use of recycled and sanitised oyster shells.

The complex nature and chemical signature of these shells make them highly attractive to spat – a term for baby oysters – or young shellfish, thereby serving as an ideal substrate for shellfish recruitment.

OzFish plans to mobilise its army of volunteers to make the quilted oyster doonas, with councils and civil engineers expected to use them in future projects.

“There will be a lot of hidey-holes for ambush predators,” Mr Porter said.

“They’ll give lots of overhanging spaces for invertebrates such as sponges, limpets, crabs and worms to hide in.”

This ambitious initiative has received funding from Queensland Fisheries through the Queensland Community Fishing Grants program, enabling OzFish to bring this innovative project to life.

It will also provide educational opportunities for students at The Southport School to learn of the importance of environmental stewardship and the role of shellfish in ecosystem health.

Paul Suttor
OzFish Unlimited