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UBC Theses and Dissertations

Factors influencing adult gonad production and larval growth and survival of the purple sea urchin (Strongylocentrotus purpuratus) Azad, Md. Abul Kalam


The continued demand for sea-urchin gonads and overexploitation of natural stocks in many countries have stimulated interest in the aquaculture of various sea-urchin species. The overall aim of this thesis was to develop rearing protocols for larval and adult purple sea urchins (Strongylocentrotus purpuratus). The specific objectives of this thesis were to determine: (1) the effect of temperature and diet on adult gonad production and (2) the effect of temperature, microalgal diet, ration, and stocking density on embryonic/larval growth and survival. To test these objectives I measured ingestion rate, gravimetric absorption, assimilation efficiency, and various gonad attributes (i.e. wet weight, water content, gonad index, texture, firmness, colour, flavour, and maturity stage) in the experiments using adult sea urchins and developmental progression from egg to prism stage, embryo length, larval length, larval mid-line body length, larval body width, larval post-oral arm length, time to reach metamorphic competency, and survival rate in the embryo/larval experiments. Adult purple sea urchins produced the highest quality gonads at 12°C when fed a prepared diet developed specifically for urchin gonad production by the Norwegian Institute of Fisheries and Aquaculture. Embryos and larvae showed more normal development and had significantly higher percent survival when reared at 11 and 14°C than at 8 and 17°C with best growth and survival occurring at stocking densities ≤100 ind ml⁻¹ of eggs/embryos and ≤1.0 ind ml⁻¹ of larvae. The single-species algal diet of Dunaliella tertiolecta and the bi-species diet of D. tertiolecta and Isochrysis sp. supported the highest larval growth and percent survival of all phytoplankton diets evaluated. Larvae fed an increasing diet ration (i.e. 2,500–10,000 cells ml⁻¹, according to developmental stage) of a mixed-species algal diet (D. tertiolecta and Isochrysis sp.) generally had significantly better growth and survival than any fixed rations (i.e. same ration throughout development) evaluated. Overall, the results from this study suggest that S. purpuratus could be an excellent potential candidate species for aquaculture development.

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