Comparative growth of juvenile Pacific oysters (Crassostrea gigas) fed unialgal vs. synthesized diets

• Main Author: Toner, Margaret Ann
• Other Authors: Horton, Howard F., Fisheries and Wildlife, Oregon State University. Graduate School
• Format: Master Thesis
• Language: English; unknown
• Published: Oregon State University
• Subjects: Oysters > Feeding and feeds; Crassostrea gigas
• Online Access: https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/8s45qd18h

The results of research designed to develop a synthesized diet as a substitute or supplement to algae for culturing the Miyagi strain of juvenile Pacific oysters, Crassostrea gigas (Thunberg) are reported. The growth of juvenile Pacific oysters fed equal amounts (based on ash free dry weights [AFDW]) of algae (Pseudoisochrysis paradoxa, lysed algae, dried oyster meat, and encapsulated lysed algae was determined in five experiments. Dried oyster meat and encapsulated lysed algae were also fed as supplements to lysed algae at three levels: 25, 50 and 75 percent of the total AFDW of the diet. In addition, the growth of oysters fed lysed and whole algal cells with and without the addition of sodium sulfamethazine (Sulmet) was compared. Growth was measured as the difference in AFDW and in shell length between treatments and an initial sample frozen at the beginning of the experiment. In the first experiment, oysters fed algae alone showed an increase in AFDW and in shell length that was significantly greater than that of oysters fed dried oyster meat alone and as a supplement to algae. In the second experiment, oysters fed lysed algae treated with or without Sulmet showed a significant decrease in AFDW from the initial sample. Oysters fed algae with and without treatment with Sulmet did not show a significant increase in AFDW. No shell growth was observed in the remaining experiments. In the third experiment, oysters fed starch encapsulated algae and algae with and without supplementation with encapsulated algae increased significantly in AFDW as compared to the initial sample. In the fourth and fifth experiments, oysters fed starch encapsulated algae only did not show a significantly greater AFDW than the initial sample, but these oysters did not lose weight during the experiments. Encapsulation appears to be a process which could be used as a delivery system for feeding synthesized diets to juvenile oysters.