GROWTH-CHARACTERISTICS OF SYDNEY ROCK OYSTERS SACCOSTREA-COMMERCIALISIN RELATION TO SIZE AND TEMPERATURE

Sydney rock oyster Saccostrea commercialis spat obtained from a single spawning of four females and two males were allocated to six size cla sses six months after spawning. The spat from each size class were dis tributed among twelve treatments, which differed in length of time the spat spent in poor growing conditions, followed by good conditions, o r conversely, in good growing conditions followed by poor conditions. A two-phase von Bertalanffy model and a regression model relating rela tive growth rate to size and water temperature gave similar fits to th e results. The monthly growth rate of spat kept in good conditions dep ended on water temperature (reflected in the phases of the two-phase g rowth model) and size at the start of the month. It is concluded that because of the nature of oyster growth, comparison of growth rates of oysters of different sizes may be misleading. (C) 1998 Published by El sevier Science B.V. All rights reserved.