Alternative Macroalgal Diets for Juvenile Greenlip Abalone ( Haliotis Laevigata ) in the Later Nursery Phase
Year: 2012
Type: dissertation
Abstract: Greenlip abalone (Haliotis laevigata) are a highly valued fishery resource, grown in aquaculture facilities around the southern states of Australia.These commercial farms have a nursery system that utilises natural algal diets adhered to vertical plates for rearing postlarval and juvenile abalone.However, as the juvenile abalone grow (5 -15 mm shell length), the current commercial nursery diet of the green alga Ulvella lens plus the diatom Navicula cf.jeffreyi does not supply adequate algal biomass to maintain commercially viable abalone growth rates at the required stocking densities.The focus of this research was to identify, develop and evaluate alternative macroalgal diets to overcome the restrictions in algal biomass during the later nursery phase.Macroalgae as an alternative natural diet for juvenile abalone can increase the algal biomass supplied on the vertical plates given its fast, 3-dimensional growth; while also considered a suitable nutrition source, as it is the primary feed of wild adult abalone.Australian abalone species have a preference for red macroalgae and to accommodate this, propagation methods including carpospore liberation, protoplast production and vegetative propagation; were assessed to determine the fitness of Rhodophyta species as an alternative diet for juvenile abalone in the later nursery phase.Protoplasts were readily isolated from red macroalgal species, however due to their limited regeneration, high cost of production and significant expertise required, the method was deemed unsuitable for utilisation in a commercial abalone nursery.Vegetative propagation successful established fragment culture of several red macroalgal species.The development of an artificial adhesion protocol, utilising active immobilisation processes through gel entrapment by the natural polysaccharide agar; enabled macroalgal fragments to be presented to juvenile abalone on the vertical plates in the nursery system.A diet of Laurencia sp.fragments adhered to the plates with agar produced juvenile abalone growth rates (50 µm.day-1 ) comparable to the current commercial nursery diet of U. lens and N. jeffreyi.The grazing resistance of the Laurencia/agar diet was low and fragments did not regenerate; so regular re-application 2003/203.Thanks go to the FRDC for funding the project 2003/203 Improvement and evaluation of greenlip abalone hatchery and nursery production, which provided my scholarship.Also to all the industry participants that allowed me access to their vast resources and facilities while conducting this research, thank you.In particular the Western Australian Fisheries Marine Research Laboratories and Challenger TAFE for the aquaculture facilities required too complete two of the large-scale abalone feeding trials.To the managers of Great Southern Marine Hatcheries in Albany, Steve Parsons and Rick Lambert, thank you for allowing me access to the nursery and weaner systems to complete one of the large-scale abalone feeding trials and providing the juvenile abalone required.Thanks also to Bay Side Abalone in Bremer Bay for the 30,000 juvenile abalone used in the Multi Diet and System Feeding Trial (Section 5.2).A special mention must go to Mark Davidson for his assistance and expertise on a range of aspects within this research, including SSBA diving, macroalgal collection, abalone spawnings, nursery feeding trials, aquaculture system construction and maintenance.Not to mention the fishing trips, rugby viewing and associated activities.His invaluable assistance was most appreciated when he and his wife Jane Davidson allowed me to live with them for a year while I conducted nursery trials at Great Southern Marine Hatcheries in Albany.x A big acknowledgment to Samuel Hair, who not only went through undergraduate Marine Science with me but we also conducted our research on abalone aquaculture together.The time and effort we both put into assisting each other during our PhD candidature was invaluable, particularly the extracurricular research into home brewing.I would also like to
Author: Lachlan W. S. Strain
Language: English
Subfield: Aquatic Science
Domain: Life Sciences
SDGs: Life below water, Zero hunger
Open Access status: green
OpenAlex ID: W2128343418