Optimising growth and survival in Irish aquaculture of abalone and sea urchins

Abstract

Increased demand for abalone and sea urchins globally has resulted in increased production of these commercially important invertebrates in aquaculture. Transfer of aquaculture technology from established producing countries to Europe has resulted in the application and implementation of new technologies by farm operators in Ireland. The industry-based research presented in this thesis addresses key industry barriers in invertebrate aquaculture, focusing on production and on-growing methods for the European abalone Haliotis tuberculata and the commercially important native sea urchin Paracentrotus lividus. To resolve knowledge gaps in the production of algivorous invertebrates in Ireland four main issues were investigated: 1- Industry, market and production constraints for the non-endemic species of abalone H. tuberculata and H. discus hannai were reviewed and evaluated. Findings indicated the current status and direction of the culture of abalone in Europe. 2- New culture methods were developed for the green encrusting macroalgae Ulvella lens as it is known to increase settlement rates of swimming abalone and sea urchin larvae. Both abalone and sea urchins have similar preferences to settlement cues and the technology for settlement is common to both industries. Ulvella lens has been used and implemented successfully into the abalone industry in producing countries such as Japan and Australia. 3- Culture methods developed for U. lens were applied to the P. lividus culture with the aim of implementing this developed technology into sea urchin aquaculture in Ireland. Due to the decline of the commercial P. lividus fishery in Ireland, increased interest has developed in the commercial culture of this species. The findings of this industry-based research indicate the need for increased commercial scale research addressing the production constraints that hamper the industry as a whole. 4- Novel mixed macroalgal-meal diets enriched with bioavailable phosphorus were investigated for increased growth in the diet of H. tuberculata, and compared against Palmaria palmata. Weaning diets for juvenile abalone normally incorporate some form of animal protein, which does not belong in the natural diet of juvenile abalone as they are algivorous by nature. Phosphorus is limiting in the diets of abalone, and may not be available as it is bound in an indigestible form such as phytate.