First trial deployment of hatchery scallops off Rottnest a success
Persistence, science and innovation have laid the foundations for a more productive and sustainable saucer scallop fishery for Western Australia, as hatchery-reared juvenile scallops have been successfully deployed for the first time off Rottnest Island.
The marine shellfish team at the Department of Primary Industries and Regional Development (DPIRD) recently deployed about 5000 scallop spat, testing the transport and deployment process to release the spat into the Rottnest fishery.
The $2.7 million scallop fishery stock enhancement project includes support and investment by DPIRD, industry partner One Sea Pty Ltd, and the Fisheries Research and Development Corporation on behalf of the Australian Government.
DPIRD’s shellfish aquaculture research manager, Roger Barnard said the scallop larvae and spat were successfully cultured in the Hillarys shellfish hatchery after induced spawning of broodstock collected from the Rottnest fishery.
Spat were cultured in the hatchery for over four months to 5-15mm size on a mixed microalgae diet, before being deployed.
Mr Barnard said the two-year research project aimed to boost wild scallop stocks and develop a more productive and sustainable fishery, increasing resilience and mitigating the effects of climate change and marine heat waves.
“Our team of dedicated technical officers and research scientists, together with water supply and systems support staff, have done exceptionally well developing innovative techniques and systems to reliably culture scallop larvae and spat in the hatchery,” Mr Barnard said.
“The team has been testing a number of key variables to develop successful hatchery protocols, including algae feed rates and species, water exchange rates, temperature and settlement media. Moving forward, we are focused on propagating larger numbers of scallops.”
DPIRD marine shellfish research scientist Lotus Hassan said the successful deployment trial was a team effort, with DPIRD’s Aquatic Science and Assessment (Ecosystem and Invertebrate Trawl), and Aquatic Research Management assisting, and Shark Research providing the boat.
“As part of our research, we are also testing the feasibility of an ocean-based nursery, using a Floating Upweller System (FLUPSY) and lantern nets to grow out scallop spat to a larger size prior to release, with an aim to increase survival post-deployment,” Dr Hassan said.
“For this trial deployment, we recorded the movement of scallops deployed near the seafloor. We also tested the survival of the deployed spat by bringing back a sub-set of spat to Hillarys.
“The majority of spat survived and thrived on feeds naturally available, growing up to 20mm in size, indicating the transport and deployment process was effective and can be upscaled when required.”
One Sea Director, Clayton Nelson, said the deployment demonstrated the commitment by the project partners to meeting milestones in the development of this project.
“The future is looking positive and we are all very excited at the progress so far,” Mr Nelson said.
WA has wild scallop fisheries located off the coast of Shark Bay and the Abrolhos Islands, on the sandy sea floor. There is also a South Coast scallop fishery and the Rottnest Island Boutique scallop fishery located off the coast of Fremantle.
Scallop spat are grown out at the marine research centre at Hillarys before release.